ESTRACK (ESA's Tracking Stations Network)
ESTRACK (ESA's Tracking Stations Network)
ESA's ESTRACK supports the Agency’s and 3rd party spacecraft, during both critical and routine mission phases. In order to ensure the required continuous and reliable communication capability, a set of ground stations are placed at the Australian, American and European longitudes. In addition, an ESA terminal is hosted at Malindi, Kenya. As from 1968 this ground stations network has been augmented as mandated by mission requirements, whilst maintaining a general-purpose character to the maximum extent possible. The latter ensures integrity of the network, common interfaces to control centers, efficient spare holding capabilities, and thus its cost efficient operations and maintenance.
After having developed and operated a European network supporting low and near Earth spacecraft (e.g. Kiruna, Redu, Kourou), in the last years ESA focus has been put on the sustaining and development of a LEOP infrastructure (Kourou, Malindi and New-Norcia) and deep-space infrastructure (located in Australia, Spain and Argentina). At the same time, ESA has developed a partnership with cooperative agreements and commercial suppliers complementing the ESA capabilities for the support of critical and routine operations in the Earth-Earth domain. This paper focuses on the strategic evolution of ESTRACK, ensuring that such strategic asset for Europe will be able to support the ESA future missions roadmap. 1)
Some background: In the sixties, during the early phase of the space exploration era, Europe initiated its space venture, including launchers and ground infrastructure programs. In the early seventies, the European Space Agency started to deploy its 15 meter antennas around the world with ground stations in Redu (Belgium), Villafranca (Spain), Odenwald (Germany), Kiruna (Sweden), Kourou (French Guyana). In the eighties, Carnarvon (Australia) complemented this set of ground-stations for the support of the first ESA deep space mission: Giotto. The Carnarvon antenna was moved in 1986 to Perth.
In the nineties and with the development of a deep-space program led by Rosetta, ESA decided to initiate the procurement of a first deep-space antenna to be located in New-Norcia (Australia). The inauguration of that antenna took place on the 5th of March 2003. Two antennas in Cebreros in 2005 (Spain) and Malargüe in 2013 (Argentina) complemented the ESA deep-space network.
In 2008, ESA deployed a 5.5 meter antenna on Santa Maria Island in the Azores archipelago, Portugal, in order to track Ariane launchers. The initial purpose was the launch of ATV (Automated Transfer Vehicle) missions for the ISS on board Ariane 5. That antenna is still in use for the tracking of Arianespace launchers.
Finally, in the 2010 decade, ESA deployed two small antennas, one in New-Norcia (Australia) for LEOP and launcher tracking support and one in Malindi (Kenya) for LEOP support.
In parallel to the extension of ESTRACK, ESA established a cooperative network (Figure 1, green sites) with other Agencies (e.g. NASA, JAXA, CNES, DLR, etc.).
As ESA celebrates the 100th launch of Ariane 5 in September 2018, the Agency’s worldwide ground station network is also marking ten years of providing vital tracking services to launchers soaring out of Kourou. 2) 3)
ESA's Earth-orbiting satellites and probes out in the Solar System are ultimately dependent on a small network of ground antennas, keeping them connected to their home planet. For ten years, this network has also been doing the same job for Europe's high-flying launchers.
Legend to Figure 1: This map is representational only and not all locations are shown with complete accuracy. The ESA tracking station at Perth, Australia, was retired from service in December 2015. The ESA stations at Villafranca and Maspalomas, Spain, were transferred to industry in 2017.
•Blue indicates core ESA-owned stations operated by the Estrack NOC (Network Operations Center) located at ESA’s European Space Operations Center (ESOC), Darmstadt, Germany. 4)
• Orange indicates Augmented Estrack stations, procured commercially and operated on behalf of ESA by commercial entities.
• Green indicates Cooperative Estrack stations owned and operated by external agencies, but regularly providing services to ESA missions on an exchange basis.
"ESA’s ventures into space have sent back vast quantities of scientifically vital data and beautiful images from our Solar System, yet without this little-known network, most of these incredible insights would never have reached Earth." explains Gerhard Billig, responsible for managing launcher tracking support at ESA's operations center in Germany (ESOC).
Named ESTRACK, this global system of ground stations provides links between satellites in orbit and the teams on Earth that control them, and of course the scientists who analyze their data.
The core Estrack network comprises seven stations in seven countries on three continents, all are centrally controlled from the Agency’s operations center in Darmstadt, Germany. Four of these stations are used for tracking satellite or launchers near Earth and feature 13 m, 13.5 m or 15 m dish antennas: Kourou (French Guiana), Redu (Belgium), Santa Maria (Portugal) and Kiruna (Sweden).
ESA's ground network was established in 1975, with the first 15 m-diameter station located at Villafranca del Castillo, Spain, for the International Ultraviolet Explorer mission (and since then, the original Villafranca location has expanded to become ESAC (European Space Astronomy Center), ESA’s major establishment in Spain.
In a typical year, the Estrack network provides over 15,000 hours of tracking support to 20 or more missions, with an enviable service availability rate above 99%.
The activities at the ESA Redu core station include one antenna, RED-1, currently used for providing TT&C support to the Galileo program. This support is formally confirmed until end 2018, further extensions might be possible. The loading of the RED-1 core station is therefore satisfactory until the end of the support to Galileo program.
New Strategy: With the increased number of supported missions as well as the development of commercial facilities, ESA decided to re-center its ground segment approach around three axes:
1) Maintain and develop strategic owned components for deep-space, astronomical and EO missions as well critical support such as LEOP, maneuver, launcher tracking...
2) Maintain and develop cooperation with other agencies, building partnership and cross-support with both non European and national European agencies.
3) Develop a commercial partnership for routine support of near-earth missions. In this context, ESA has handed over to national entities assets that were not any longer considered mandatory and somehow redundant with commercial capabilities. The following sites were affected:
- The Perth antenna was dismantled and handed-over to Portugal in 2017. The 15 meters antenna will be used in Santa-Maria for commercial purposes.
- The Villafranca and Maspalomas antennas were handed over to Spain in 2017.
ESA Low and Near Earth Missions Infrastructure: Located in the northern part of Sweden, the Kiruna site is made available to ESA based on an international agreement between ESA and the government of Sweden (1986).
The station is equipped with two terminals, namely Kiruna-1 (KIR-1) and Kiruna-2 (KIR-2) are Cassegrain antennas, both providing S-Band transmit and S- and X-band receive capabilities (S/SX). The Kiruna-1 antenna is a 15m parabolic main reflector and a shaped hyperbolic subreflector in an elevation over azimuth over tilt axis mount.
The Kiruna-2 antenna is a 13m parabolic main reflector and a dichroic hyperbolic subreflector with heater (S-band pass through, X-band reflection), in an elevation over azimuth over tilt-axis mount.
The two terminals provide the following services:
• TT&C and payload data reception
• Radiometric measurements (Ranging, Doppler, Meteo, Autotrack Angles)
After the first frequency down-conversion stage, the downlink L-band signals of KIR-1 and KIR-2 are fed via the Antenna Downlink Switch (ADLS) into tunable L-band down-converters for conversion to 70 MHz intermediate frequency (IF) and further signal routing through the 70 MHz switch.
Telecommands are received at the station using the SLE protocol and transmitted to the frequency upconverters at 230 MHz. The uplink signal is routed to the KIR-1 and KIR-2 S-band uplinks or alternatively to the ESRANGE terminals.
In addition to the Kiruna infrastructure, the Kourou Diane core station (KRU) is currently primarily allocated to the support of XMM-Newton. The loading of the Diane station is therefore satisfactory at least until the end of the XMM mission. The station is ideally located for LEOP support to Near Earth missions also with highly elliptical orbits and features a dedicated X-Band Acquisition Aid. As such it will be supporting the execution of the critical LEOP of upcoming missions, namely Galileo, Metop-C, BepiColombo, and SOLO (Solar Orbiter). The Kourou station is considered a strategic infrastructure enabling ESA to execute autonomously the critical operations of its missions. In fact the Sand X-band LEOP capabilities in Kourou are not easily replaceable by commercial services or international support. In the mid term, considering its characteristics, it is expected that the Diane station will also be ideally placed to support the future (cis)-lunar exploration missions.
The terminal is a Cassegrain antenna with a reflector system, parabolic main reflector and hyperbolic sub reflector, with shaped contours for high gain and low side lobes. The antenna has S/X-band transmit and S/X-band reception capabilities (SX/SX). The back-end Telemetry and Telecommand interface is based on SLE services.
Low and Near Earth Missions Needs: Currently Earth Observation (EO) missions are typically operated in S-band (TT&C) with payload data transmitted in X-band (8.025-8.4 GHz). Polar orbit of most of the EO spacecraft dictates the location of the ground stations at polar regions, which increases interference and congestion in X-band due to limited available bandwidth. Interference and congestion will not be limited to X-band but due to terrestrial communication needs it will also likely affect S-band.
To overcome the congestion issue and to provide higher data rates the 26 GHz frequency band has been allocated (25.5-27.0 GHz, K-band) to dump payload data. Missions like NASA/NOAA Joint Polar Satellite System (JPSS-1) recently launched and EUMETSAT EPS-SG (EUMETSAT Polar System Second Generation), planned to be launched starting in 2021, will transmit payload data at 26 GHz. TT&C will still be in S-band.
Both JPSS-1 and EPS-SG will be operated by dedicated antennas in S-band for TT&C and will receive payload data by dedicated antennas operating at 26 GHz. In order to establish a reliable link with the satellite an antenna of a minimum size of 6m will be required at 26 GHz.
The new Sentinel missions (i.e. Sentinel expansion/extension) currently under initial preparation might also consider transmission of payload data at 26 GHz.
In summary, future EO missions might adopt novel approaches, moving from the current configuration (TT&C in S-band, payload data in X-band) to novel solutions [TT&C services in X-band and payload data at 26 GHz (K-band)].
This evolution in the EO space segment requires an equivalent adaptation of the ground segment, in particular as regards the ground stations capabilities.
ESA Low and Near Earth Strategy: As presented previously, future EO missions will likely adopt novel approaches, moving from the current configuration (TT&C in S-band, payload data in X-band) to novel solutions (TT&C services in X-band and payload data at 26 GHz (K-band)). In the past years a series of ground segment technology activities have been conducted in order to anticipate the above evolution and enable the provision of communication services.
Based on this, a feasibility study shall be conducted to assess the possibility to upgrade the existing KIR-1 terminal by adding X-band uplink (as required for future EO missions) as well as autotrack capabilities in this frequency band. In addition, the option to add K-band reception capabilities shall be evaluated.
Based on this, a feasibility study shall be conducted to assess the possibility to upgrade the existing KIR-1 terminal by adding X-band uplink (as required for future EO missions) as well as autotrack capabilities in this frequency band. In addition, the option to add K-band reception capabilities shall be evaluated.
In 2018, ESA will acquire a new 6m S/K-band antenna as part of a dedicated project. As a follow-on initiative, it is envisaged to deploy this terminal at the Kiruna station, providing enhanced capabilities in support of current and future EO missions. Initially it could be used as test and validation facility in support to JPSS-1 and EPS-SG. Later it will be able to provide services to ESA and other partners EO missions (e.g. new Sentinels and Earth Explorer missions). A detailed plan covering the conversion of the prototype into a full operational system is being prepared.
By 2020 the following capabilities will then become available in ESA Kiruna Station:
1) KIR-1: 15 m antenna operating in S/X-band but designed to be easily upgraded to X-band uplink for upcoming EO mission requiring TT&C services in X-band
2) KIR-2: 13m antenna operating in S/X-band (unchanged)
3) KIR-3: 6m antenna for K-band payload data reception.
Deep-Space and Astronomy Mission Needs: An estimate of the ground stations utilization has been performed covering the next decade, and taking into account the ESA missions under development as well as potential missions such as L5 Space Weather (ESA) and WFIRST (NASA). Official launch dates and nominal mission lifetime have been retained . Among the future missions, of particular relevance is ESA Space Weather spacecraft, with a launch assumed in 2023. With its 24/7 operational profile, this mission will require high performance deep space communication services.
Furthermore, the analysis assumes launch of NASA WFIRST mission in 2025. ESTRACK will provide communication services during the complete duration of this mission.
Based on the above analysis, the estimated load of ESA’s three deep space antennas over the time frame 2018-2030 indicates a major increase as of 2021. By 2023 the communication needs of the missions will exceed by up to 50% the currently available capacity.
The implementation of additional resources is deemed necessary: up to two new 35 m antennas deployed over Australia and Argentina longitudes respectively, are essential in order to support the average 26,000 tracking hours/year required by the upcoming missions.
In summary, independent access to space remains a strategic objective for Europe. While in the future, space missions will be more and more demanding in terms of performances (e.g. increased data throughput) and capabilities (e.g. new frequency bands), the needs for optimizing the costs and possibly sharing the facilities is an important aspect of ESA's future activities.
To that end ESA considers necessary to develop partnership approaches either in a cooperation model, or possibly in a co-owning model ensuring an optimization of the use and of the associated running costs. ESA is today embarking in such strategic development and has initiated discussions with partner agencies. The future of space activities in space or in ground will require increased cooperation and increased partnership.
The development of new technology whether for near Earth, LEOP or space exploration remains as well a strategic targets. To that end a number of studies aim at preparing European technology for the future requirements targeting at improving performances and capabilities of the network.
On medium term, ESA intends to extend the existing deep-space sites by deploying additional deep-space terminals in New-Norcia (Australia) and in Malargüe (Argentina) as well as maintaining and developing strategic assets such as Kiruna (Sweden) and Kourou (French Guyana).
Figure 5: ESTRACK - ESA tracking station network profile (video credit: ESA)
Status of ESTRACK
• June 16, 2022: Construction has begun in Australia on ESA’s fourth deep-space antenna, which will help fill a gap in supporting communications and data download for upcoming missions exploring our Solar System, studying our Universe and protecting Earth from solar hazards and risky asteroids. 5)
- ESA representatives met with representatives from Australia’s national and regional governments and from the Australian Space Agency today, 16 June, to kick off active construction of the new antenna located at ESA’s existing New Norcia ground station, 140 km north of Perth, Western Australia. The Australian Space Agency is providing local and financial support to the project.
- ESA’s deep-space antennas are used to send commands and receive information and science data from missions venturing far from Earth – to the Moon, the Sun, distant planets or even asteroids.
- The three existing deep-space antennas in ESA’s global tracking station network – Estrack – are located roughly 120 degrees apart in longitude at locations in Australia, Spain and Argentina. Together, they provide continuous coverage to spacecraft almost anywhere in the Solar System.
- ESA is now constructing a fourth 35 m-diameter antenna in order to meet the rising demand for communication bandwidth as the Agency prepares and launches a new generation of deep-space and space safety missions. With global coverage already achieved, the decision was made to build a second deep-space antenna at the existing Australian site.
- “The new antenna will ensure Europe’s continued autonomous capacity to fly pioneering exploratory missions as well as to support upcoming space safety missions including Hera and Vigil,” says ESA Director General Josef Aschbacher. “It will also strengthen ESA’s important relationship with Australia while helping ensure we always get the most science out of every mission.”
- “The Australian Space Agency is excited to deepen our relationship with ESA, as we look to continue to grow the local space sector,” says Enrico Palermo, Head of the Australian Space Agency. “This project will extend Australia and Western Australia’s pedigree and heritage in deep space communications, which can be traced right back to the 1950s. It will also unlock the exchange of new technical know-how, as Australian suppliers help design, develop and test the antenna.”
From Down Under to New Frontiers
- From the new antenna in Australia, signals will be sent across interplanetary space, past the orbit of Mars, to the Jupiter system as ESA’s upcoming Juice spacecraft navigates its complex journey to Jupiter’s icy moons – Ganymede, Europa and Calisto. Set to launch in 2023, Juice will embark on a mission to help scientists answer important questions, such as whether life could have – or has – emerged elsewhere in the Solar System.
- It will also support the Agency’s Euclid space telescope, also due to launch next year, on its mission to illuminate the true nature of dark matter and dark energy by observing billions of galaxies as far as 10 billion light-years from Earth.
- Turning towards the Sun, the antenna will support ESA’s Vigil space weather mission. Due to launch at the end of the decade, Vigil will monitor our active and unpredictable star from a special vantage point that enables it to provide operators of spacecraft and vulnerable infrastructure on Earth – such as power grids – with advance warning on potentially dangerous solar flares.
A Boost to Europe, Australia and the World
- The Agency’s Estrack ground station network is a cornerstone of ESA’s international cooperation. The Agency has promoted and adopted internationally recognised technical standards that allow it to provide coverage on a cross-services basis to spacecraft from partner space agencies such as NASA and JAXA. In exchange, these partners provide equivalent support for ESA missions and activities.
- The antennas in the network are operated around the clock from ESA’s ESOC mission control centre in Darmstadt, Germany.
- he decision to construct the antenna at ESA’s existing New Norcia station was announced in April 2021. Since then, work has been underway to define the exact location for the new antenna and to upgrade the necessary infrastructure such as roads, power and data. Construction is now underway, led by prime co-contractors Thales Alenia Space from France and Schwartz Hautmont Construcciones Metálicas from Spain, and is due for completion in late-2024. The antenna is due to enter operation in early-2025.
- Australia’s national science agency, CSIRO, has been ESA’s local partner for operations and maintenance since 2019 and will likewise be responsible for the additional new antenna.
• March 29, 2022: The Indian Space Research Organisation (ISRO) is launching two pioneering scientific spacecraft this year, one to study the Sun, and one to land on the Moon – the nation’s first soft landing on another celestial body. 6)
- ESA’s global deep-space communication antennas will provide essential support to both missions every step of the way, tracking the spacecraft, pinpointing their locations at crucial stages, transmitting commands and receiving ‘telemetry’ and valuable science data.
- In June 2021, ESA and the Indian Space Research Organisation (ISRO) signed an agreement to provide technical support to each other, including tracking and communication services to upcoming Indian space missions via ESA’s ground stations.
- The first missions to benefit from this new support agreement will enable India look to the Sun and the Moon with the Aditya-L1 solar observatory and Chandrayaan-3 lunar lander and rover, both due to launch in 2022 from the Satish Dhawan Space Centre in Sriharikota Range (SDSC SHAR), India.
- “Deep space communication is an essential part of any space mission,” says Ramesh Chellathurai, ESA Service Manager and ESA Liaison Officer for ISRO. “Ground stations keep spacecraft safely connected to Earth as they venture into the unknowns and risks of space. Without ground station support, it’s impossible to get any data from a spacecraft, to know how it’s doing, to know if it is safe or even to know where it is.”
A Place in the Sun
- The Aditya-L1 solar observatory is named for the Hindu Sun god, Aditya, and the spacecraft’s future home, L1 – the first Lagrange point of the Earth-Sun system. It will study a number of properties of the Sun, such as the dynamics and origins of coronal mass ejections.
- Its home at L1 will allow Aditya to orbit the Sun at an almost constant distance from Earth, but without the planet ever eclipsing its view of our star.
- “The spacecraft will always be in the same direction from Earth as the Sun,” says Ramesh. “So, as Earth rotates, no single ground station will always be in view of Aditya-L1. Using a global station network like ESA’s is the best way to exchange data and commands with this spacecraft as often as possible.”
- ESA is one of the only agencies in the world with a network of deep space ground stations located across the planet. The Estrack network lets it track and communicate with spacecraft anytime and in any direction, up to two billion kilometres from Earth.
- The ‘big iron’ 35-metre deep space Estrack antennas, located in New Norcia, Australia, Malargüe, Argentina, and Cebreros, Spain, will all support Aditya-L1. Additional support will be provided by ESA’s 15-metre antenna at Europe’s spaceport in Kourou, French Guiana, and the commercial 32-metre deep space antenna at Goonhilly station in the UK.
- The combined ESA and Goonhilly antennas will provide tracking, telemetry and command (TT&C) support for Aditya-L1, with ISRO’s deep space antennas in India providing additional communication time.
- Data and telemetry sent back by Aditya-L1 arriving via any of the ground stations will be forwarded to ESA’s ESOC mission control centre in Darmstadt, Germany. From there, they will be sent to ISRO’s ISTRAC facility for analysis.
- ESA’s involvement in the mission has already begun. ISRO’s flight dynamics team tested the software they will use to precisely determine the location and orbit of Aditya-L1 on ESA’s Gaia observatory. ESA’s flight dynamics experts then used their decades of experience flying spacecraft across the Solar System to validate this software by comparing ISRO’s results to their own measurements.
- Meanwhile, radio frequency compatibility tests important to ensure the hardware used by both agencies can work together took place in December 2021.
Guide Me to the Moon
- The support to Aditya-L1 was soon extended to ISRO’s upcoming Chandrayaan-3 – “Moon craft” – mission to study the lunar surface at the Moon’s south pole.
- The mission comprises a lander and rover, which will spend two weeks conducting scientific and technical operations on the surface. Chandrayaan-3 would be India’s first successful soft landing on another celestial body – a major milestone for any space programme.
- ESA’s Kourou antenna and the Goonhilly station will be added to the NASA deep space stations supporting the mission and provide similar support to Chandrayaan-3 as they will to Aditya-L1.
- The ESA station support for both Aditya L1 and Chandrayaan-3 begins with the critical launch and early orbit phase and continues to the end of both missions, if required by ISRO.
India and Space
- ISRO was formed in 1969 and is headquartered in the city of Bengaluru (Bengalore). It operates a launch site and a deep space ground station located within India.
- The Organisation was among ESA’s first international partners in the 1970’s, with initial cooperation culminating in the provision of ESA instruments for ISRO’s Chandrayaan-1 lunar orbiter mission, launched in 2008.
• October 13, 2021: An upgrade to ESA’s three 35-meter deep-space antennas will boost science data return by 40% by cooling the ‘antenna feed’ to just 10 degrees above the lowest temperature possible in the Universe. 7)
Why Is This Important?
- ESA’s ground stations help us tackle some of the greatest scientific questions. They are used to send instructions to spacecraft across the Solar System and receive the data they collect via a ‘downlink’.
- The demand on the stations' downlink capacity is higher than ever before. In the next few years, the Agency is preparing to launch new spacecraft deeper into our Solar System and support missions from an increasing number of partner space agencies.
What Are the Upgrades?
- To increase downlink capacity, you must either build new antennas, or improve the performance of existing ones. ESA is doing both.
- While a new and sorely needed deep space antenna is being built in Australia, it’s important - and economical - to squeeze as much performance out of pre-existing dishes as we can. A series of upgrades across ESA’s network of ground stations is doing just that:
a) The antenna feed – the tech that connects the physical antenna to the electronic transmitter and receiver – at ESA’s three 35-meter deep-space antennas is being cooled to just 10 degrees above absolute zero (about -263°C).
b) Current upgrades will increase the amount of data that can be downlinked from spacecraft by up to 40%, allowing more high-definition images of the Sun to be received from Solar Orbiter during one communication window, for example.
c) Future upgrades across higher frequency bands will mean an increase of 80 % more data can be downloaded – that’s almost double the deep space data reaching Darmstadt!
d) This clever tech will also increase the sensitivity of ESA deep space antennas, extending their range to support future ESA missions that venture as far as Uranus and Neptune.
- “With these upgrades, ESA is pushing the limits of what’s technically possible and enabling scientists to explore new worlds and gather unprecedented amounts of data,” says Stéphane Halté, ESA ground station engineer in charge of the project together with Filippo Concaro.
- “The upgrades have come at just the right time,” says Andrea Accomazzo, Head of Solar System and Exploration Missions at ESA’s space operations center in Darmstadt. “They give us the performance we need to ease the high demand on our tracking network and continue to provide the highest standard of data return for an increasing number of scientists.”
1) The integration of the first new cryo-cooled antenna feed was completed in May 2021 at ESA’s Cebreros station in Spain.
- The upgrade at Cebreros improves the rate at which data can be processed in X-band frequencies by up to 40%.
2) ESA’s Malargüe station will receive the same X band feed upgrade in 2022 along with a new ‘Ka band’ cryo-cooled feed, where the expected data rate increase will be as high as 80%. This will greatly benefit existing missions such as BepiColombo and upcoming missions like Juice. The antenna in New Norcia will receive the upgrade at a later date.
3) Cooling the feed electronics minimizes the effects of ‘thermal noise’, allowing weaker signals to be received. Below 10 K, impurities in the metals used in the electronics begin to limit the benefits of further cooling.
4) The cryo-cooled feeds are manufactured by French company Callisto Space, which received funding from ESA during the technology’s 5-year development. Canadian company Calian conducts the integration of the new technology into the antennas.
5) The technology was tested at NASA's High Power Transmitter Test facility in 2019 at Goldstone, California, at a power output of 30 kW – roughly equivalent to the power output by 30,000 mobile phones in use at the same time.
6) Specific ultra-low noise semiconductor technology has been developed with university partners (Chalmers university and ETH Zürich) to reach the ultimate noise performance. The same technology is used today for the development of quantum computers. This is an example where ESA technology development can support the overall scientific community and support the competitiveness of European companies.
Less Cool Updates From the ESTRACK Network
- Not quite so cool, but equally necessary, ESA’s smaller dishes in French Guiana and Sweden are getting various performance improving upgrades, readying the entire ESTRACK network for ESA’s future plans in space.
- At Europe’s Spaceport in Kourou, French Guiana, ESA’s 15-meter antenna is being upgraded with new ‘TTCP modems’, allowing maximum data rates in preparation for future Moon, Earth and ‘No-name’ space weather missions.
- In Kiruna, Sweden, ESA’s two antennas will see an evolution in the fundamental ‘Monitoring & Control’ system as well as a new antenna feed and refurbishment for the 13-m ‘Kiruna 2’ dish and various enhancements to Kiruna-1.
• May 20, 2021: In recent years, ESA has designed some of the most advanced spacecraft ever built to reach exotic locations such as the Sun, Mercury, Mars, Jupiter and the Didymos asteroids – a trend that will continue into the years ahead. As missions voyage further from Earth, it is important to consider how we can continue to communicate with them and how they will navigate through space when they are so far from home. 8)
- To communicate effectively with spacecraft, we need to send and receive status, navigation and scientific data. This is achieved using ground stations on Earth. ESA operates a sophisticated system of ground stations, including three Deep Space Antennas (DSA) located around the world, providing continuous coverage as Earth rotates.
- To ensure that missions meet their science objectives, ESA continues to develop technologies to communicate with them more effectively. This includes the technologies on board spacecraft, as well as those on the ground.
Figure 10: Tracking spacecraft deep across the void. ESA operates some of the world's most sophisticated deep-space tracking stations, enabling spacecraft to maintain contact with Earth while voyaging deep into our Solar System. The essential task of all ESA stations is to communicate with our missions, sending telecommands and receiving vital scientific data and spacecraft status information. The Agency's three Deep Space Antenna (DSA) stations are located in Australia, Spain and Argentina, and are centrally controlled from the ESOC Operations Centre in Germany. They are equipped with large, 35 m-diameter parabolic dish reflectors, weighing in at 610 tons, that can be rotated and pointed with extreme accuracy. Using signal data from the stations and an advanced navigational technique known as 'delta-DOR', engineers can pinpoint the orbit of a spacecraft exploring Mars or Venus - a distance of over 100 million kilometers from Earth - to an accuracy within 1 kilometer (video credit: ESA)
What Is Discovery & Preparation Doing in This Area?
- Discovery & Preparation lays the groundwork for ESA's short- to medium-term future activities. The Preparation element recently ran the Open Space Innovation Platform (OSIP) Campaign 'What's Next – new ideas for space missions and concepts'. A number of ideas for new deep space missions were addressed, especially supporting future human interplanetary spaceflight, Mars exploration and missions to near-Earth objects.
- As part of its provision for future deep space missions, Discovery & Preparation has conducted several investigations into future ESA's space science missions. A study that finished in 2009 developed a system to enhance the operation of these missions – which typically travel relatively far from Earth – through a flexible planning, scheduling and optimization process. A more recent study proposed an end-to-end mission simulator to improve their efficiency.
- Discovery & Preparation has also contributed significantly to ESA's Proba missions, which test new technologies in space. A 2009 study envisaged an interplanetary Proba mission – Proba-IP – to travel to a near-Earth object and validate autonomous onboard guidance, navigation and control technologies.
- On top of these general investigations, Discovery & Preparation has carried out more specific studies that focus on individual deep space communication and navigation technologies.
Communication – Making Long-distance Relationships Work
- Communicating with distant spacecraft is difficult. The signals that pass between the spacecraft and ground stations are very weak and because of the large distances, it takes them a long time to travel between the two. It can take up to 24 minutes for a signal to travel between Earth and Mars, for example, and almost an entire day to receive a signal sent by NASA's Voyager 1 – a spacecraft that has travelled beyond the edge of the Solar System.
- As there are strong constraints for equipment on board spacecraft, a lot of the more complex communications technologies are incorporated into the ground stations. Many Discovery & Preparation studies have contributed to developing such technologies.
- A study that finished in 2012 explored the feasibility of developing klystrons entirely within Europe. These devices transform electrical power into amplified radio signals to send commands from ground stations. The study set the requirements and objectives for the development of such a device, as well as defining an industrial environment and potential roadmap for the future. Klystrons are now used in ESA's network of ground stations; you can discover more about them in the video at the beginning of this article.
- Another study focused on selecting the best ground station architecture for future deep space missions. By gathering data about the current performance of ESA's Deep Space Antennas, as well as collecting the needs and characteristics of future missions, the study calculated the characteristics of the ground system that would be required to meet these needs. The study noted that communicating with optical frequencies is more efficient than the more traditional radio frequencies.
- Another study explored how ESA's Optical Ground Station (OGS) – usually used for communicating with nearby spacecraft – could be used to communicate with deep space missions.
Navigation – Turning Time Into Distance
- Good communication is vital not only for collecting science and status data, but also for navigating spacecraft through the Solar System. To navigate spacecraft we need to know their position, which is no easy feat when they are so far away. But by measuring three parameters – distance, velocity and the angle at which a spacecraft is located in the sky – it is possible to calculate a satellite’s position down to a small box-shaped region of space.
- One element that is essential to navigating deep space is timing, in particular ensuring that the time on board spacecraft is synchronized with the time on the ground. To calculate where a spacecraft is in the Solar System, we precisely measure the time it takes for electromagnetic waves to travel between the spacecraft and an antenna on Earth. Navigators on Earth then transmit course adjustments. A 2007–2009 study explored forward thinking techniques to synchronize time on board deep space probes for accurate navigation, in particular looking into low-cost options. A parallel study found that an accuracy of ten nanoseconds for a signal passing from a spacecraft to Earth is possible without using an onboard atomic clock.
- Navigating a spacecraft to distant locations requires a team of scientists and engineers using sophisticated radios, large antennas, computers, and precise timing equipment. While the DSAs have been the standard tool for navigating spacecraft in the past, the network comes with limitations and partial autonomous navigation is becoming more common. One method that has been explored more over the past decade is to navigate using pulsars – magnetized, swiftly rotating, dying stars that emit beams of electronic radiation out of their magnetic poles.
- Millisecond pulsars – which have rotation periods of less than ten thousandths of a second – offer the most precise timing standard known. In a kind of celestial GPS, spacecraft can measure the time between receiving each pulse of radiation from three different pulsars, looking for tiny changes in the arrival times to pinpoint its location.
- This was still a very novel idea between 2012 and 2014, when Discovery & Preparation supported two studies that explored the feasibility of deep space navigation with X-ray pulsars. The first was carried out by the UK’s National Physics Laboratory and University of Leicester, and the second by the University of Helsinki. Among other discoveries, the research found that the benefits of such a technique include increased spacecraft autonomy, improved position accuracies and much lower mission operating costs due to the substantial reduction in the use of the associated ground-based systems.
- Pulsars are not the only astronomical objects with the potential to be used for navigation. A 2016 study investigated the feasibility of an onboard visual navigation system for ESA’s Hera mission (then AIM), which will visit double asteroid Didymos later this decade. The system laid the path towards developing such a system; Hera will use its onboard camera to determine the position of the asteroids with respect to the background stars. Hera will also demonstrate communication with a ground station via an optical link as well as communication between the main spacecraft and two CubeSats.
- What about making use of Global Navigation Satellite Systems that enable Earth-based navigation to negotiate our way further afield? Navigation satellites orbit around 22,000 kilometers above Earth's surface. As they point down towards Earth, any spacecraft below them are served well by the signals they send out. But around ten years ago, engineers started demonstrating that spacecraft outside the orbit of navigation satellites could also navigate in space using their 'spill over' signal.
- In 2012, two Discovery & Preparation studies kicked off to investigate a seemingly radical question: could this spill over signal even be used to navigate our way around the Moon, and if so, what kind of receiver would we need to build to be able to use these signals? The studies – led by Deimos and Joanneaum Research – found that indeed, the signal from navigation satellites orbiting Earth could be used to navigate the Moon's surface. But with the signal being so weak, they concluded that a new type of receiver would need to be built. ESA has now invested in the development of such a receiver, and is exploring whether it could be demonstrated on the Lunar Pathfinder mission.
What Else Is ESA Doing?
- ESA has several missions already working in deep space, including Solar Orbiter, ExoMars and BepiColombo. Next year will see the launch of the JUpiter ICy moons Explorer (JUICE), which will spend at least three years observing Jupiter and three of its largest moons. In 2024, ESA’s planetary defence mission, Hera, will set off to visit an asteroid, in the process discovering more about these rocky objects and finding out if we could deflect an asteroid on collision course with Earth.
- ESA's ambitious plans for the next decade of human and robotic space exploration will take us from the ISS to the Moon, a deep-space gateway and a Mars landing. Concrete steps are already being taken towards exploring the Moon; NASA's new Orion vehicle, with a European service module at its core, will build bridges to Moon and Mars by sending humans further into space than ever before.
Figure 13: Destination: Moon. This 8-minute film gives an overview of the past, present, and future of Moon Exploration, from the Lunar cataclysm to ESA’s vision of what Lunar exploration could be. Why is the Moon important for science? What resources does the Moon have? Is there water? Why should we go back and how will we do it? (video credit: ESA)
- For all robotic and human missions to the Moon, asteroids, Mars or beyond, at least one DSA is essential for communications. ESA's Operations directorate controls spacecraft – including those voyaging deep into the Solar System – and develops and manages the necessary ground infrastructure. Prior to every mission launch, Operations teams carefully design and build the ground segments that enable engineers to control satellites in space and receive and distribute their data.
- ESA Operations oversees ESA's tracking station network, Estrack, the core of which comprises seven stations in seven countries, including the three DSAs. Furthermore, the directorate is currently operating the tiny OPS-SAT satellite, which is devoted to testing and validating drastically improved mission control capabilities.
- In addition to the daily operation of spacecraft exploring space hundreds of millions of kilometers away, ESA's operations teams continually work to develop new capabilities to support future missions, including flight-dynamics techniques, delay-tolerant networks, deep-space communication technologies and innovative satellite control software and systems.
What Are Other Space Agencies Doing?
- ESA shares Estrack capacity with other space agencies, who in return provide tracking services to ESA missions under a number of resource-sharing agreements. These include networks and stations operated by ASI (Italy), CNES (France), DLR (Germany), NASA's Deep Space Network and Goddard Space Flight Center and JAXA (Japan).
- For example, NASA's Deep Space Network stations routinely support Mars Express (as well as other, now-completed missions such as Rosetta, Huygens and Venus Express), while Estrack is supporting Japan's Hayabusa-2 mission. In recent years, Estrack has provided support to missions operated by China and Russia, as well as tracking the descent of NASA rovers to the surface of Mars.
- Other space agencies are also developing their own technologies for communicating with and navigating deep-space spacecraft. For example, NASA has developed a deep space atomic clock and an X-ray navigation device that determines the position of a spacecraft anywhere in the Solar System, and JAXA has worked on a navigation system using highly accurate 3D radar and navigation guidance control technology for rendezvous and orbit transition to the neighborhood of the Moon.
• November 19, 2020: Today, ESA’s ground stations are helping fetch rocks from the lunar surface; tomorrow, they will enable new missions that will make the Moon a routine destination. 9)
a) Ground stations are used to communicate with spacecraft across the Solar System.
b) ESA’s ground station network is uniquely equipped to support lunar exploration missions due to advanced technology and a global geography.
c) In the next few weeks, ESA will support China’s Chang’e-5 lunar sample return mission by relaying signals from the spacecraft during two critical phases.
d) These ground stations are an important element in the Agency’s ambitious lunar exploration goals, supporting ESA, international partners and European industry.
- ESA's Estrack network is a global system of ground stations providing communication between spacecraft and ESA’s ESOC mission control centre in Darmstadt, Germany.
- Mission controllers use the large antennas to control their spacecraft and receive the data they send back, whether from Earth orbit, on the way to the Moon or the Sun, or further out in the Solar System.
- “Our network of tracking stations has the capability to communicate with any type of mission in the Solar System,” says Simon Plum, the Head of Mission Operations at ESOC. “In the future, it will increasingly support the lunar missions of ESA and its partners.”
- In November and December 2020, they will provide communication support to the Chinese Chang’e-5 lunar sample return mission.
- On 23 November, ESA’s Kourou station, located in French Guiana, will track Chang’e-5 for several hours shortly after it launches. During this early phase, it is important to determine exactly where the spacecraft is in order to establish a communication link and verify the health of the newly launched craft. Kourou station will provide a way for the Chinese mission control team at the Beijing Aerospace Control Centre to acquire data from the spacecraft and confirm the status of the mission and its orbit.
• September 2020: ESA's Kiruna ground station in northern Sweden celebrates 30 years of space excellence. Near the top of the world, at a latitude of almost 68° north and sited 38 km east of Kiruna town, the Kiruna ground station has been operational for 30 years. Ideally positioned to support polar-orbiting missions, the station is a crucial gateway for much of the data enabling us to study our planet's oceans, water and atmosphere, forecast weather and understand the rapid advance of climate change. With its two sophisticated antennas, it also supports some of ESA’s scientific missions such as Integral and Cluster. The station is part of ESA’s Estrack network linking all Agency missions to the ESOC mission control centre in Darmstadt, Germany. 10)
Figure 16: ESA's Kiruna celebrates 30 years of space excellence (video credit: ESA)
• September 9, 2020: North of Sweden and the Arctic Circle, ESA’s Kiruna ground station is celebrating 30 years looking skyward, connecting us to many of our beloved and most pioneering space explorers. 11)
- The station, equipped with two dish antennas 15 m and 13 m in diameter, is a crucial space gateway, bringing data down to Earth that lets us study our planet's oceans, water and atmosphere, understand weather patterns and the rapid advance of climate change.
A Fairy Tale Start
- In 1986, ESA and Sweden agreed to establish satellite tracking facilities near the top of the world, in the region of Salmijärvi. Here, on a 20-hectare site some 38 km east of Kiruna town and just 10 km from the ESRANGE launch site, the Station was sited.
- In September 1990, His Majesty The King of Sweden accompanied by ESA’s then Director General Reimar Lüst pressed the button that triggered the antennas first track, inaugurating the station and marking the start of its operational life.
- Situated above the Arctic Circle at 67.9º latitude, Kiruna is the northernmost station in ESA's Estrack network, an optimal geographical location to track polar-orbiting satellites. As such, the station is mainly devoted to the support of Earth Observation missions, bringing home data from some of ESA’s renowned windows on the world.
Kiruna’s First Job
- In July 1991, the station began routine support to ESA's then-new ERS-1 mission, with an on-site staff of some 25 engineers. A few years later in 1994, the station's systems got their first upgrade, meaning the station could also support the follow-on ERS-2 mission, launched the following year. The two radar missions could then be operated on a tandem basis, marking a first for Europe.
- In 2002, Kiruna took on communication responsibility for ESA's Envisat mission, the largest civilian Earth Observation satellite ever flown. As the 8-tonne satellite and its 10 onboard instruments would be producing large quantities of data it was again necessary to upgrade the station. A second, 13-meter dish antenna was installed to deliver high-data-rate capability in X-band.
- Kiruna's antennas and station systems are normally operated remotely from ESA's Network Operations Centre, located at the Agency’s mission control in Darmstadt, Germany. Here, operators are on duty 24 hours a day, all year round.
- For maintenance and day-to-day troubleshooting on site, Kiruna relies on a local team of engineers. These specialists also work 'on console' if direct intervention is needed during critical spacecraft maneuvers or launch activities.
- Over the course of 30 years Kiruna station has established an enviable record providing reliable communication links with dozens of Europe's most important and renowned missions, such as historic star-mapper Hipparcos and gravity-measuring GOCE.
- From its remote polar location, Kiruna today supports a wide range of European missions including Integral, an orbiting gamma-ray telescope, and Cluster, a set of four identical satellites flying in a tetrahedral formation to gather data on the plasma environment between the Sun and Earth.
- Kiruna also supports three of ESA's Earth Explorer missions, wind-mapper Aeolus, the magnetic field measuring trio Swarm and ice-charting Cryosat-2. As well as these, the station supports the five Sentinel satellites flown by ESA on behalf of the European Union's Copernicus program, providing accurate, timely and freely accessible environmental monitoring.
- In a typical month, more than 700 hours of communication link-ups are made between Kiruna’s two terminals and passing satellites, up to 15 different spacecraft in all.
- This means the station is working around the clock, providing tracking support for 23 hours and 20 minutes each day with an average service performance success of 99.8%. These communication ‘passes’ enable the station to download vital science data and upload fresh commands for the coming orbits.
Ever Evolving, Kiruna Eyes the Future
- Three decades have passed since Kiruna’s royal inauguration, and in that time the ground station has cemented itself as one of Europe’s most important space facilities both for ESA and its partner agencies.
- In those years the station has undergone continuous development and expansion, driven by the increasing technical and scientific needs of the missions it has supported.
- As space technology evolves further and its importance in our lives grows, Kiruna station will need to keep reinventing itself. Upcoming Earth Observation missions will transmit higher rates of data at new frequency bands, and the station will need to be ready for these and all the as-yet uninvented technologies that space missions will continue to pioneer.
- Happy birthday, Kiruna! We look forward to the next 30 years.
• February 5, 2020: For the first time, an ESA deep space antenna has sent commands to two ESA spacecraft, simultaneously, at the Red Planet. Late on 30 January, the 35 m New Norcia dish in Western Australia ‘spoke’ to Mars Express and the ExoMars Trace Gas Orbiter (TGO). Talking with two voices at two different frequencies ensured the signals sent didn't interfere with each other. The successful test is an important step in increasing the flexibility of ESA’s Estrack network of antennas across the globe, to find, control, or receive data from missions across space. 12)
Deep Space Conversations
- The vast majority of conversations between Earth and space involve one antenna on the ground, one spacecraft in orbit or out in the Solar System, and signals at a particular frequency going between the two.
- In cases where several spacecraft are located in one part of the sky (all in orbit around Mars for example), it's possible for an antenna to ‘see’ all of these spacecraft at once.
- As ESA ground stations have four receivers, they can in principle receive data from up to four spacecraft simultaneously.
- This technique, called MSPA (Multiple Spacecraft Per Aperture), is used routinely by ESA’s Estrack and NASA's Deep Space networks.
- However MSPA only works one way. While it allows the ground station to receive data from multiple spacecraft, it can only ‘speak’ to one at a time.
Estrack Gets Chatty
- Ground stations are built with two transmitters, pieces of equipment used to generate and transmit electromagnetic waves (light) carrying messages or signals. Normally, stations send signals using only one transmitter at a time, and the other is there as back up in case the first breaks down.
- The recent test with the New Norcia ground station, the first of its kind, saw the deep dish use both transmitters at the same time to control Mars Express and ExoMars TGO.
- Normally, these two Martian orbiters receive their command signals in very similar frequencies, known as the ‘X-band’, between 8–12 GHz, but from different stations or using one station at different times.
- However, Mars Express can also receive signals in the ‘S-band’, at a frequency of approx 2.8 GHz, which until now has been saved for emergencies.
- The perfect alignment of events; two spacecraft close in the sky, able to receive ‘telemetry’ signals at different wavelengths, and a deep space station able to send both ‘telecommand’ signals simultaneously, made it possible to combine ‘Multiple Spacecraft per Aperture’ with ‘Multiple Uplink per Aperture’ (MUPA), in an ESA first.
- Historically, there hasn't been a need to use one dish to command multiple simultaneous missions, as there wasn't such a demand on the antennas.
- However, ESA's global network of antennas, Estrack, is running at peak capacity, meaning that the antennas can't fully serve the needs of all missions until the network capacity is increased (for Estrack overview, see Figure 1).
- Deep space missions have the added problem that they require large antennas, of which there are only three (for now) in the network, located in Australia, Argentina and Malargüe.
- For many years, Mars Express was one of only three spacecraft orbiting Mars. Now, the Red Planet has seven such orbiters, operated by various space agencies, with more on the way.
- ESA's control center has a team dedicated to ensuring all missions get sufficient ground station time. By working out new ways of sharing ground stations, we allow more users to access current resources while new antennas are being built.
- Find out more about Estrack, and check out, in real time, which spacecraft each ground station in the network is ‘talking’ to with EstrackNow.
• August 29, 2019: Every moment, conversations are taking place between antennas across the globe and missions exploring our planet, Solar System and deep space. So, what is ESA's 35-m antenna in Australia looking at? — The New Norcia antenna provides routine support to missions orbiting Mars like Mars Express and Exomars TGO as well as the Gaia space observatory, in the process of making the world's most precise map of the stars in our Milky Way galaxy and BepiColombo on its way to Mercury. 13)
- With the launch of ESA’s ESTRACK now 'dashboard’, you can find out exactly which missions are communicating with which antennas at any moment, and discover more about what individual missions are up to - what is their mission and how far away are they?
- Explore the ESTRACK network in realtime or go to http://estracknow.esa.int.
- Check out our guide to using the site, here.
• January 2019: Planned installation of cryogenically cooled antenna feed. 14) This year, ESA's ground station boffins are planning to deploy a new cryogenically cooled "antenna feed" – a gizmo used to transmit and receive deep space signals – on the Agency's three deep-space antennas.
- The ground stations routinely communicate with missions like BepiColombo – heading to Mercury, Gaia – surveying stars in our Galaxy, and ESA's two spacecraft at the Red Planet, Mars Express and the ExoMars Trace Gas Orbiter.
- ESA’s 35 m antennas receive data from working spacecraft, in what’s called a ‘downlink’. As the Agency prepares to launch new missions deeper into our Solar System in the next few years, including Juice to Jupiter and the ExoMars Rover, as well as missions designed to generate large quantities of data, such as the future Sun-watching Lagrange mission, use of the stations' downlink capacity is set to grow significantly.
- This means the stations have to 'up their game', and the new antenna feed is expected improve data return by 40% at the high frequencies used for spacecraft command and control. The feed must be cooled to just 10 K (just 10 degrees from absolute zero, about -263 C) for normal operation.
- "While receiving extremely faint signals, the new feed should be capable of transmitting command signals to spacecraft at very high power of more than 25 kilowatts", says ESA ground station engineer Stéphane Halté. "This is similar to the amount of power transmitted by 25,000 mobile phones switched on simultaneously."
- The prototype antenna feed was mounted on NASA’s Deep Space Station 13 (Figure 18), at NASA's High Power Transmitter Test facility, in Goldstone, California. It was tested in December 2018 with the assistance of experts from the NASA Jet Propulsion Lab's Deep Space Network.
- Testing successful, this ESA/NASA cooperation has cleared the way for the new technology to be rolled out at across ESA’s deep space ground stations, part of the Estrack network, within this year.
• Ten years of launcher tracking - 2018 (Ref. 4): In addition to catching signals from satellites almost anywhere, 2018 marks ten years since Estrack stations began tracking the launch vehicles that deliver these satellites into orbit, starting in March 2008, with the Ariane 5 rocket that carried the ATV-1 cargo vessel, Jules Verne.
Initially established to communicate solely with satellites, Estrack was expanded to support their rockets in 2008 with the establishment of a ground station and 5.5 m-diameter antenna on Santa Maria Island in the Azores archipelago, Portugal. The first Estrack station with the capability to track launchers, Santa Maria provided ESA with the independent means of receiving information from launchers through all phases of their flights.
Santa Maria joined Estrack at the same time that the Automated Transfer Vehicle (ATV)-series of missions got underway; the five ATVs were a series of expendable spacecraft developed by ESA to carry supplies to the International Space Station, at about 400 km altitude.
The special Ariane launch trajectory for these missions required a dedicated station in the middle of the Atlantic Ocean. For the same reason, this station has continued to be used for all launches of Galileo satellites, helping orbit Europe’s new navigation system.
In contrast, the original Ariane launcher tracking station network — operated by the French space agency CNES from Europe's Spaceport in Kourou — is tailored for a different launcher trajectory followed by most launches from Kourou. These deliver telecom satellites into geostationary orbit at 36,000 km.
Santa Maria tracks all launch vehicles operated from Europe's Spaceport: including the three world-changing launch vehicles, Ariane 5, Soyuz and Vega.
Estrack stations provide teams on site with vital information acquired from the launchers soaring overhead, which is then passed on to the CNES and Arianespace teams who control their flights.
“ATV-2 in 2011 was a particularly memorable launch,” says Gerhard, who was at Santa Maria station at the time. Just minutes after liftoff from Kourou, while the Ariane rocket was in radio contact with our station, we could see it whizzing high over our heads in the clear night-time sky. We could actually make out the upper stage thruster burning! It was amazing to see the rocket speed across the horizon, like a comet through the sky. And what we saw visually, was being confirmed on our screens via the live telemetry link.”
To date, the Estrack stations in Portugal and Western Australia have supported 35 launches, many of which were monitored by more than one ground station; 16 launches have been supported from Santa Maria, and 34 from Western Australia (20 from Perth and 14 from New Norcia).
Upgrading down under: In 2010, the existing New Norcia antenna in Perth, Western Australia, was upgraded for launcher tracking. It was used for tracking not only ATV and Galileo launches but also rockets delivering satellites to ‘Sun-synchronous orbits’ and onto interplanetary trajectories.
“For a decade now, tracking services for both the launcher and the satellite are provided, a unique and important capability during the first, critical moments of a satellite’s mission,” says Gerhard.
In 2010, the existing New Norcia antenna in Perth, Western Australia, was upgraded for launcher tracking. It was used for tracking not only ATV and Galileo launches but also rockets delivering satellites to ‘Sun-synchronous orbits’ and onto interplanetary trajectories.
“For a decade now, tracking services for both the launcher and the satellite are provided, a unique and important capability during the first, critical moments of a satellite’s mission,” says Gerhard.
Since the closure of the Perth station in 2016, its launcher tracking capability has been transferred to ESA’s deep space station at New Norcia, also in Western Australia.
• Transferring ownership of three ESA ground stations: 15)
As part of ESA’s strategy to foster commercial competitiveness in Europe while focusing on its core aims, the agency has transferred ownership of several ground tracking stations for reuse by external organizations. By the end of 2017, ESA will have transferred three stations to national organizations in Spain and Portugal, who will take over the provision of satellite tracking services to a wide variety of commercial customers.
The three stations involved in the transfer are all equipped with 15 m-diameter dish antennas, suitable for supporting near-Earth missions, and are located in Spain, at Maspalomas and at ESA’s space astronomy center near Madrid, and in Perth, Western Australia.
The new operators will be able to use the stations to offer tracking services on a commercial basis to customers worldwide, which also includes ESA, leaving the Agency free to focus on meeting the demanding technical requirements of its deep-space stations, in Spain, Argentina and Australia, and on operation of a select group of four other stations.
“The handover increases commercial capabilities and capacity in Europe, not only to the benefit of ESA but also for commercial partners,” says Yves Doat, Head of Ground Facilities Infrastructure at ESA’s mission control center, Darmstadt, Germany. “ESA will continue developing the new technologies needed for future communication, including very high data-rate optical communication and networking with exploration partners at the Moon, Mars and other deep-space destinations.”
The handover of the Perth station was notable. The station’s frequency licence was withdrawn by the national telecoms regulator in 2015, and the station could no longer operate where it was. After being decommissioned, ESA was faced with the not insignificant cost of tearing it down and disposing of the structure and technical equipment.
“Instead, the government of Portugal made a bid for the station and, following a cost-sharing agreement for dismantling and transportation, it was shipped to Santa Maria island, in the Azores, where it is being recommissioned and placed back into service by 2018,” says Yves.
Augmented network: The ESA-owned and operated core Estrack network is complemented by commercially operated stations provided thru service contracts with organizations such as the Swedish Space Corporation (SSC), Spain's National Institute of Aerospace Technology (INTA) and Kongsberg Satellite Services AS (KSAT, Norway).
These include tracking stations located at South Point, Hawaii (USA), Santiago (Chile), TrollSat, Antarctica, and Svalbard (Norway) and Dongara (Australia). These stations are used especially during the LEOP phase of a mission immediately following launch, when the flight control team needs continuous communication with their satellite, beyond what can be provided by ESA's own stations.
International cooperation: ESA shares Estrack capacity with other space agencies, who in return provide tracking services to ESA missions under a number of resourcing-sharing agreements. These include networks and stations operated by ASI (Italy), CNES (France), DLR (Germany), NASA's Deep Space Network and Goddard Space Flight Center and JAXA (Japan).
For example, NASA's Deep Space Network stations routinely support Rosetta and Mars Express (as well as other, now-complete missions such as Huygens and Venus Express), while Estrack is supporting Japan's Hayabusa-2 mission to asteroid 1999 JU3 (arriving in 2018). In recent years, Estrack has provided support to missions operated by China and Russia, as well as tracking the descent of NASA rovers to the surface of Mars.
This global cooperation allows all agencies to make use of a wide number of ground stations in geographically advantageous locations, maximizing efficiency and enhancing scientific returns for all. This cooperation is made possible, in part, through ESA's strong support for the development and adoption of internationally recognized technical standards for sharing tracking data.
In accordance with ITU radio regulations and agreements between ESA and Estrack host countries, Estrack stations are fully licensed and their operation respects requirements such as minimum elevation angle and maximum power radiated, as well as any site-specific constraints included in these agreements.
Estrack stations are designed in accordance with the European Cooperation for Space Standardization (ECSS) standards.
Ground Stations Network
DSA (Deep Space Antennas)
In 1998, ESA decided to establish its own network for tracking deep-space probes to cope with the expected rapid rise in the number of interplanetary missions. The aim was to establish three terrestrial stations about 120° apart in longitude to provide continuous coverage as Earth rotated.
In the 2000s, the first of three 35 m-diameter Deep Space Antennas (DSA) was built in New Norcia (Australia), followed by stations at Cebreros (Spain) and Malargüe (Argentina). These feature some of the world’s best tracking station technology and enable communications with spacecraft voyaging hundreds of millions of kilometers in space. In August 2016, New Norcia station received signals from the international Cassini spacecraft orbiting Saturn, across more than 1.4 billion km of space.
ESA Deep-Space Station Infrastructure: The deep space tracking network, part of the ESTRACK core network, consists on a set of three 35m class ground stations, distributed around the world and located in: Cebreros (Spain), Malargüe (Argentina) and New-Norcia (Australia). The ESTRACK deep-space network is suitable for a wide range of missions: interplanetary, space astronomy, solar observation, lunar exploration, etc. Since its debut, it has supported all major ESA scientific missions, including Rosetta, Mars Express, Venus Express, ExoMars, and Gaia. The network is also used in cross-support of other’s agencies mission such as: Cassini (NASA), Insight (NASA), Hayabusa (JAXA).
The three terminals provides the following services:
• Radiometric measurements (Ranging, Doppler, Meteo, ΔDOR)
New Norcia Facility: DSA-1
In March 2003, ESA inaugurated a new deep-space station 8 km south of the town of New Norcia, which is about 150 km north of Perth, in Western Australia. — The large antenna was completed in 2002, and engineers conducted pointing tests using NASA’s Stardust mission in the lead up to operational readiness. It entered service as the first of the Agency’s three deep-space tracking stations in March 2003, and has been used for communications with Mars Express, Rosetta, Venus Express and Gaia, among other ESA and partner agency missions. The antenna supports data transmissions and receptions in both S- and X-band.
The coordinates of the 35 m antenna are: -31° 2' 53.61", +116° 11' 29.40". The antenna is sited at 252.26 m with respect to the WGS-84 reference ellipsoid, a mathematically- defined reference surface that approximates the Earth's geoid surface.
As of 2017, ESA’s deep-space ground station at New Norcia, Western Australia, is also being powered in part by sunlight, thanks to a new solar power ‘farm’ completed in August. The farm has 840 photovoltaic panels arranged in five double rows with a rated capacity of 250 kW. This is expected to generate 470 MWh of electricity annually, about 40% of the station’s annual needs and equal to the electricity needed to power 134 typical households. 17)
“While we’ve only just completed the first full month of operation, the solar facility has already reduced our cost of purchasing electricity from the local power company by at least 30%,” says ESA’s Marc Roubert. “In the coming summer months, given some sunny, clear skies, we even expect to be able to deliver electricity back to the local grid.”
The installation began in 2015 and is expected to provide a full return on investment within about 15 years. — In future, ESA will consider upgrading the sites in Spain and Argentina with solar power as well.
Status of DSA-1
• On 29 April 2021, ESA and the Australian Space Agency announced the construction of a second 35-meter, deep space antenna at ESA’s New Norcia station, located 140 km north of Perth in Western Australia. 18)
- The 620-ton antenna will be a new model complementing the existing deep space antenna on the site, with novel functionality and support for additional communication frequencies.
- It will feature the latest in deep space communication technology, including a super-cool ‘antenna feed’ that will be cryogenically cooled to around -263ºC and increase data return by up to 40%.
- The antenna will be so sensitive it can detect signals far weaker than the signal from a mobile phone - if there were one - on the surface of Mars.
Investing in Europe’s Future With Australia
- “We are happy to announce the latest addition to ESA’s state-of-the-art deep space communication network and this important next step in our relationship with the Australian Space Agency,” says ESA Director General Josef Aschbacher.
- The Agency’s deep-space stations are supporting a growing number of increasingly sophisticated exploration probes like Gaia, BepiColombo, Solar Orbiter and, soon, the ExoMars rover, Euclid and JUICE, as well as upcoming space safety missions like Hera and the Sun-monitoring space weather mission.
- “ESA’s network is crucial infrastructure that helps enable cooperation and cross-support with missions flown by partners like NASA, JAXA and other agencies, and this boosts science return and efficiency for all involved,” adds Director General Aschbacher.
- “It’s also part of the ESA infrastructure that can support new space and commercial actors, a key element of ESA’s Agenda 2025 priorities.”
- ESA has budgeted €45 million for the new antenna, covering antenna procurement and construction as well as upgrades to station buildings and services. While the prime contractor will come from an ESA Member State, a significant portion of the budget will be spent in Australia with the involvement of a number of Australian companies.
Figure 21: Video recorded during a drone flyover of ESA's 35 m-diameter deep-space antenna at New Norcia, Western Australia, in October 2018 (video credit: ESA/D. O'Donnell, CC BY-SA 3.0 IGO)
- ESA’s ground station and antennas at New Norcia, Western Australia, are locally operated and by the Commonwealth Scientific and Industrial Research Organisation (CSIRO), the Australian government agency responsible for scientific research. CSIRO similarly operates NASA’s deep space antenna complex located at Tidbinbilla near Canberra.
- “The new antenna is not only positive progress in the Agency and ESA’s cooperative relationship, but also an important contributor to the local economy which will help grow Australia’s civil space industry,” says Head of the Australian Space Agency Enrico Palermo.
- The new deep space antenna at the New Norcia site is a joint undertaking contributing to the long-term cooperation between ESA and Australia in the space domain. It enables significant economic, technology and scientific benefits for both partners, and will pave the way for further collaboration in areas such as space communication, space situational awareness and mission operations.
Rising Demand for Deep Space Communications
- Deep space antennas are used to communicate with spacecraft on missions that take them far from Earth – whether to the Moon, the Sun, the planets or even asteroids.
- The number of deep space missions launched worldwide is rapidly increasing, and so is the need to upload commands and download status updates as well as valuable scientific data from these intrepid explorers.
- ESA’s large antennas communicate with spacecraft so far out in space – as far as 1.44 billion kilometers from Earth and even further in future – that they can only ‘listen’ to spacecraft in a relatively small area of the sky at any one time. If two spacecraft are in a very similar direction from Earth – both at Mars, for example – it is possible to use one antenna to communicate with them both at the same time.
- But as space exploration continues to take us in new directions, there will be a greater need to maintain frequent communication with spacecraft located in widely different portions of the sky – such as Mars and Mercury. To keep these missions safe and get the most out of the data they collect, ESA needs more antennas.
Around the Globe: ESA Ground Station Network
- ESA's ground station network – Estrack – is a global system of stations providing communication links between spacecraft and ESOC, ESA’s European Space Operations Centre in Darmstadt, Germany. The core Estrack network comprises seven stations in seven countries.
- The new antenna will be ESA’s fourth deep space antenna and will join existing 35-meter antennas in New Norcia, Malargüe (Argentina) and Cebreros (Spain).
- Located in Western Australia, New Norcia provides a strategic geographical position allowing around-the-clock coverage of deep space missions, with a perfect complement to the sites in Argentina and Spain.
- Building a second antenna on an existing site allows for cost-effective construction, maintenance and operation. Funding for the new antenna was confirmed at ESA’s Space19+ ministerial council in 2019.
- Studies to determine the exact location of the new antenna on the New Norcia site began at the end of 2019. Construction is due to be completed in 2024 with the antenna entering operation in the second half of that year – just in time to help out with the JUICE and Hera missions, among many others.
• December 12, 2019: New Norcia Facility: DSA-4 (Deep Space Antenna 4). It's confirmed! ESA is building its fourth deep space antenna – much like the Cebreros dish — that will ensure upcoming missions like JUICE and the Hera mission have someone to talk to when they get to space. 19)
'Deep Space Antenna 4' will be located at the New Norcia ground station in Western Australia, home of Europe’s first 35-meter antenna (DSA-1).
ESA’s ESTRACK network is currently made up of three deep space stations across the globe as well as a number of smaller dishes, and it is running at peak capacity. Following analysis of future mission needs, this fourth antenna will provide much-needed communication support to upcoming European and non-European deep-space missions.
Using the latest super-cool technology, the ‘antenna feed’ – through which data flows in from space – will be cryogenically cooled to just 10 degrees Kelvin (only 10 degrees above absolute zero, about -263 C). Doing this, incredibly, is expected to increase the amount of data returned by 40% at the high frequencies used for spacecraft command and control.
Such technology will also be used in the Cebreros station pictured here, and the Malargüe station, dramatically increasing the amount we can ‘hear’ from space.
Work should be finished on the station by the end of 2023, ready to begin operations by mid-2024 – just in time for the JUICE and HERA missions.
• November 27, 2019: Large antennas are our only current way of communicating through space across vast distances, and every now and then they need to be spruced up to ensure we can keep in touch with our deep-space exploration spacecraft. Early this November, ESA’s Deep Space Antenna in New Norcia, Australia, was subject to major maintenance, with a wide range of updates implemented to keep it in pristine order. 20)
- To communicate with ESA’s fleet of spacecraft, the position of the antenna needs to be controlled with high accuracy. The huge 35 meter diameter construction relies on gearboxes to alter its position, offering sweeping views of every inch of the sky – and it was time these were replaced.
- Australia’s national science agency, CSIRO, has been responsible for day-to-day operational support and maintenance at the New Norcia station since June 2019.
- “It was wonderful watching the elevation and azimuth gearboxes being swapped out, in a perfectly choreographed operation using heavy duty chain hoists and a large crane,” describes ESA’s Andreas Scior, responsible for the upgrade activities.
- “This was the first time such an operation was conducted on an ESA deep space antenna, and despite its complexity, all involved teams managed to conduct the activity smoothly returning the antenna to service within just a week.”
- Scheduled maintenance of high-tech equipment also took place while the antenna power was off, as well as a series of frequency and timing enhancements, an upgrade of data routers and the installation of a new safety rail.
• July 25, 2019: It may not look like it, but this giant dish in Australia spends its time in in-depth conversation with a number of European deep space missions. 21)
- Deep Space Antenna-1 (DSA 1) routinely provides support to Mars Express and Exomars TGO, currently orbiting the Red Planet; the Gaia space observatory, in the process of making the world's most precise map of the stars in our Milky Way galaxy; BepiColombo on its way to Mercury; and Cluster II, studying Earth's magnetic environment.
- Preparations are also underway for critical 2020 events, including a crucial BepiColombo flyby and the launch of Exomars RSP and Solar Orbiter.
- Discoveries by these spacecraft and others would not be possible without ESA ground stations collecting their data, making it available to researchers across the globe and ensuring we can command and communicate with the explorers from our Operations Center on Earth.
• June 4, 2019: The 35-m deep space antenna in New Norcia, Western Australia, is being looked after by a new team, led for the first time by a female site manager, Suzy Jackson. 22)
- The New Norcia station is key to communicating with Europe’s missions across the Solar System and observing the Universe, including Mars Express currently in orbit around the Red Planet and BepiColombo – on its way to Mercury.
- As well as the deep space dish, the station also includes the nimble 4.5-m antenna – both able to track rockets following lift-off from Europe’s spaceport in Kourou, French Guiana, as they deliver their precious cargo towards Earth orbit or deep space.
- The maintenance and local operations (M&O) of the impressive site is, as of 1 June, being managed by Australia’s national science agency, CSIRO, which also runs NASA’s Canberra Deep Space Communication Complex.
First Female Site Manager
- No stranger to radio communication, Suzy Jackson previously worked as an engineer on the development of CSIRO’s Australian Square Kilometer Array Pathfinder – a radio telescope in Western Australia.
- In her new role as New Norcia M&O service Site Manager, Suzy is ensuring her team of seven is on top of maintenance of the giant dish, making sure all of the different equipment is running properly and carrying out checks on system performance.
- “Australia is well suited to radio astronomy and radio communication with spacecraft and rocket launchers,” explains Suzy.
- “In Western Australia, you don’t have to go far before the population density drops straight away. It’s terrible for mobile phone coverage but just perfect for clear skies, without interference from people’s phones and televisions.”
- Such an environment means the station, one of the three biggest antennas in ESA’s tracking network, ESTRACK, is able to receive large quantities of data from spacecraft over vast distance – the farthest so far was NASA’s Cassini spacecraft more than 1.4 billion km from Earth.
• December 20, 2018: ESA’s 35 m antenna in Australia has now been powered by the Sun for over a year, cutting costs and reducing carbon emissions by 330 tons - equivalent to 1.9 million km driven by car. 23)
- The solar plant at the New Norcia station in Western Australia started its first full month catching solar rays in August 2017. One year later, it had produced 470 Megawatt-hours of power – enough to supply 120 four-person homes for a year, fuelling 34% of the total electricity consumption of the station
- In order for the tracking station to be powered 100% by renewable energy, more panels would be required. Other sources of energy could also be used such as kite power, hydrogen or geothermal energy.
- “I am really happy with these results – they reach beyond our initial expectations when we began the solar-power upgrade and I would be thrilled to see the same development spread to our other ground stations,” explains Marc Roubert, ESA's ground stations maintenance engineer.
- With this success, ESA engineers will investigate possible similar upgrades for other stations.
- Ultimately, Marc says, it would be a real achievement to get all ESA ground stations in the Estrack network completely off the mains power grid. This way, they can continue to track and communicate with satellites orbiting Earth and in deep space, while reducing the carbon footprint of the Agency’s giant 'eyes on the skies'.
• December 14, 2018: Australia’s national science agency, CSIRO (Commonwealth Science and Industrial Research Organization), has been selected to provide maintenance and operational support for the European Space Agency’s deep space tracking station at New Norcia, 130 km north-east of Perth in Western Australia. 24)
- This is the first time that an Australian organization has been selected to manage day-to-day operations at the ground station. The ESA control center in Darmstadt, Germany will continue to remotely control its spacecraft and satellites via the station.
- A 35 m antenna at the tracking station, DSA-1, provides support to ESA’s missions exploring our solar system. It tracks their locations, sends commands to control spacecraft, and reliably receives data collected hundreds of millions of kilometers from Earth.
- These missions include BepiColombo, which was launched in October 2018 and will explore Mercury – the closest planet to our Sun – where it will endure temperatures in excess of 350°C; and Mars Express, which is currently orbiting the Red Planet collecting information about its geology, atmosphere, surface environment, history of water and potential for life. ESA's ExoMars trace gas orbiter and Gaia mission are also supported.
- The station provides tracking support to scientific and interplanetary missions operated by other international space agencies like NASA and Japan’s JAXA under resource-sharing agreements.
- The station provides tracking support to scientific and interplanetary missions operated by other international space agencies like NASA and Japan’s JAXA under resource-sharing agreements.
- The contract is due to start on 1 June 2019; a three-month handover from the current contractor will start on 1 March 2019.
- Federal Minister for Industry, Science and Technology Karen Andrews said the agreement was another important milestone in the growing Australian space sector. "Since 1979, Australia and ESA have had treaties in place to enable European Space Agency ground stations on Australian soil to track spacecraft and interplanetary missions and Australia has unique view of the southern hemisphere sky that provides us with a natural advantage for viewing the Universe," Minister Andrews said.
- "The facility at New Norcia has been in operation since 2003 and now, for the first time, an Australian organization will provide critical maintenance and operational support at the station. Through its management of NASA's Canberra Deep Space Communication Complex, as well as Australia’s leading radio astronomy facilities, CSIRO has rich experience operating large, complex infrastructure for spacecraft tracking and astronomy research. - This follows the announcement earlier this week that Adelaide will be the location of the Australian Space Agency, and is a further demonstration that momentum is building for the local space industry. The space industry plays an essential role in the lives of all Australians, from providing us with weather forecasts and telecommunications, to inspiring the next generation of students."
• On 26 October 2018, a group of EU Ambassadors to Australia (including Australia, Belgium, Croatia, Cyprus, Czech Republic, France, Greece, Hungary, Italy, Netherlands, Slovenia) visited ESA's deep space ground station at New Norcia, Western Australia. 25)
- ESA's deep space stations feature some of the world’s best tracking station technology and enable communications with spacecraft voyaging hundreds of millions of kilometers in space.
- The New Norcia station's geographic location on the western side of Australia enables it to not only communicate with missions traveling deep in our solar system, but also to track rockets launched from ESA's Spaceport in Kourou, French Guiana, acquiring the 'first signals' from newly orbited satellites.
- Gerhard Billig, responsible for managing launcher tracking support at ESA's ESOC operations center in Germany, showed the ambassadors around the station, briefing them on the critical support it has offered to some of ESA’s best known missions, including Exomars, BepiColombo and Gaia.
- Ambassadors were also given a tour of the 35 m-diameter deep dish antenna — in August 2016, this station received signals from the international Cassini spacecraft orbiting Saturn, across more than 1.4 billion km of space, the most distant 'catch' ever made by ESA.
- The tour also included the ‘NNO-2’ small dish and the technical facilities. The NNO-2 dish was established in 2015 and has since caught the signals from newly launched satellites, including the latest, Aeolus and BepiColombo.
Cebreros Facility: DSA-2
ESA’s new deep space radio antenna in Cebreros (Ávila, Spain) was officially inaugurated on 28 September 2005. The new 35 m antenna is ESA’s second facility devoted to communications with spacecraft on interplanetary missions or placed in very distant orbits. Cebreros’ first task was that of tracking ESA’s Venus Express spacecraft. 26)
The Cebreros station, DSA 2 (Deep Space Antenna 2), is located 77 km west of Madrid, Spain. It hosts a 35-meter antenna with transmission and reception in X-band and reception in Ka-band. It provides routine support to deep-space missions including Mars Express, Gaia and Rosetta. 27)
Cebreros provides routine operations support to ESA deep-space missions, as well as other agencies' missions under resource-sharing agreements.
The antenna dish is 35 m in diameter and the entire structure is 40 m high and weighs about 620 tons. Engineers can point the antenna with a speed of 1 degree per second in both axes. Cebreros' servo control system assures the highest possible pointing accuracy under the site's environmental, wind and temperature conditions.
For routine operations, Cebreros is controlled from ESOC. On-site management and maintenance is provided by INSA (Ingenieria y Servicios Aerospaciales S.A).
The Cebreros antenna incorporates state-of-the-art technology and the site was chosen for ESA's second deep-space antenna for several reasons. Since this antenna must be positioned 120 degrees East or West of our first deep-space antenna, DSA 1, in Australia, an ideal location would have been ESA's ESAC (European Centre for Space Astronomy), located in Villafranca, near Madrid. However, active urban development in the ESAC surroundings could have caused interference.
The Cebreros location, which formerly hosted a NASA tracking station, is equally good and is distant from densely populated areas.
Malargüe Facility: DSA-3
The Malargüe station, Deep Space Antenna 3, is ESA's newest tracking station and is located 30 km south of the city of Malargüe, about 1200 km west of Buenos Aires, Argentina. DSA 3 hosts a 35 m-diameter antenna with transmission and reception in X-band and reception in Ka-band. 28) 29)
DSA 3 was inaugurated in December 2012 and entered full service in early 2013. Today, it provides daily support to missions such as Gaia, Mars Express, Rosetta and ExoMars.
Location: The coordinates of the antenna are 35° 46' 33.63" S (35.776°S), 69° 23' 53.51" W (69.398°W), and the station is sited at 1550 m above sea level.
The Malargüe station incorporates state-of-the-art technology. Its technical facilities comprise Ka-band reception (31.8–32.3 GHz) and X-band transmission and reception. It is prepared to host Ka-band transmission (34.3–34.7 GHz) and K-band reception (25.5–27 GHz). Its main functions are to receive telemetry, send telecommands and perform radiometric measurements (ranging, Doppler, Delta-DOR) on scientific and deep-space craft.
Operations: The station provides routine spacecraft tracking support to ESA's deep-space missions such as Venus Express and Mars Express, and scientific missions such as Herschel and Planck, as well as to other agencies’ missions under resource-sharing agreements. Malargüe will also support future ESA scientific missions, including LISA Pathfinder, Gaia and BepiColombo.
For routine operations, the station is remotely controlled from ESOC, Darmstadt, Germany. Local maintenance and operation is provided by a team of five engineers.
Status of DSA-3
April 11, 2019: ESA's 35 m radio antenna in Malargüe, Argentina, has had a major refurbishment. Extensive modifications made will now allow the ESTRACK network to support future mission like Euclid, launching in 2022, and to transfer data at much higher rates. 30)
Upgrades to the ESA Malargüe station, and similar upgrades carried out in the Cebreros station located in Spain in 2017, make a big difference to deep space missions.
Currently missions like Gaia are able to send back data at a channel rate of 10Mbit/s. Euclid will send back data at a rate of 149Mbit/s – a similar increase in speed as we have experienced in our internet browsing in the last 10 years.
Euclid, which will orbit at the Lagrange point L2, will be fitted with the 26 GHz band radio giving it a higher bandwidth for transferring data to and from Earth, significantly increasing the scientific information returned over time.
The refurbishment of Cebreros and Malargüe stations, will allow ESA deep space antennas to receive broadband signals at 26GHz as well as the conventional X-band frequency.
Highlights of the Upgrade
The core of the Malargüe Ground Station antenna optical system is the beamwaveguide. This is a set of mirrors that redirect the signal from the spacecraft to the antenna feeding system.
The central mirror in the set plays a key role in the upgrade. By rotating the mirror in the center, you can redirect the signal to different receivers with different frequencies.
When the central mirror is rotated to the deep space position, operators will be able to simultaneously use X-band and Ka-band waves – the kind of signal sent by deep space missions like BepiColombo.
When the central mirror is rotated to the near earth position, a newly developed multiband feed system will enable simultaneous X-band and K-band communications.
There is a placeholder position for exclusive communication at X-band using the new 80 kW high power amplifier. The 80 kW amplifier is currently being developed and is expected to be deployed to ESTRACK by 2024.
In addition, a new generation of low-maintenance cryogenic amplifiers for improved performance have been installed, as has the latest portable satellite simulator – which will be compatible with Euclid’s high data rates.
Challenges to Upgrade
This upgrade has provided unique challenges for the teams charged with seeing it through. The mirrors must be very precisely aligned, with a maximum of 3.5 millidegrees of angular tolerance. To achieve this precision, photogrammetry was used.
ESTRACK antennas also support a very wide range of flying missions, with a high operational load. To minimize the impact on operations, the complete refurbishment had to be completed in only five weeks.
Teamwork Is Key
The success of the upgrade relied on the dedication and expertise of each individual and their capability to work together effectively as a team.
Coordination between more than twenty people carrying out the upgrades has been paramount – and it has been achieved by keeping the team motivation high and ensuring communication and information flowed among the five industrial partner companies who worked together on the refurbishment.
Goonhilly Goes Deep Space
ESA has three deep-space dishes, in Australia, Spain and Argentina, that provide leading-edge performance and full-sky coverage for tracking and communicating with missions like Mars Express, Gaia and ExoMars. Later this year, they will add the new BepiColombo mission to Mercury and, in the near future, ESA’s Solar Orbiter, Euclid and Cheops. 31)
“The amount of science data flowing in from ESA’s current missions, not to mention from future missions with improved instruments, is growing strongly,” says ESA’s Pier Bargellini, responsible for network operations. “By the middle of the next decade, ESA’s deep-space communication needs for supporting today’s missions, like ExoMars, and upcoming spacecraft, like Juice, is expected to exceed our present capacity by around half.
Developing commercial capacity: This is why ESA engineering teams are excited by a new initiative aimed at redeveloping part of Goonhilly Earth Station, an existing commercial station in Cornwall, UK, to enable it to provide Europe’s first deep-space tracking services on a commercial basis.
Under the project, a 32 m-diameter dish built in 1985 will be upgraded to provide fast data links for missions far beyond Earth – typically exceeding 2 million km. In the future, once commercial capacity is available, ESA’s deep-space antenna network will focus on supporting sophisticated missions demanding high-performance systems.
The project will be initially funded through a €9.5 million investment from the UK’s Cornwall & Isles of Scilly Local Enterprise Partnership, a public–private regional economic development body, and will later include a smaller investment from ESA.
“Once the station upgrade work is complete, in about 24 months, Goonhilly will be able to complement ESA’s own stations, and provide deep-space tracking for the Agency’s missions as well as those of other space agencies or from private space start-ups aiming to exploit the Moon or mine asteroids,” notes Klaus-Jürgen Schulz, responsible of ESA ground station engineering.
Goonhilly, established in 1962 and at one time the largest satellite station in the world, with over 60 dishes of varying size, is well known in the UK. Its antennas have brought iconic images to UK TV viewers, including Muhammad Ali fights, the Olympic Games, the Apollo 11 Moon landing and 1985’s Live Aid concert.
With the growing demand for deep-space tracking for both space agencies and new commercial space companies, the Goonhilly upgrade is an excellent example of how ESA can foster new business for European industry through engineering contracts to transform existing antennas into state-of-the art deep-space ground stations.
Status of the Station
• October 10, 2019: If you’re planning on flying a robotic or even human mission in the near future to the Moon, an asteroid or even Mars, one indispensable requirement you’ll face is the need for at least one deep-space tracking dish to communicate with your craft. 32)
- The Goonhilly 6 antenna is part of the Goonhilly ground station in Cornwall, England, home to over 60 dishes able to track satellites close to home, in highly elliptical orbits as well as planetary and celestial objects further afield.
- Built in 1985, the antenna will be upgraded to provide fast data links for missions far beyond Earth, typically exceeding 2 million km.
- ESA currently has three deep-space dishes in Australia, Spain and Argentina, providing full sky coverage for tracking and communicating with missions at Mars such as ExoMars and Mars Express as well as BepiColombo - currently on its way to Mercury. Future ESA missions such as Solar Orbiter, Euclid and Cheops will soon be added to this list.
- However, by the middle of the next decade, ESA’s deep-space communication needs for its current and upcoming missions is expected to exceed present capacity by around half.
- This is why ESA teams are excited by the upgrade of Goonhilly 6, which will enable the UK station to provide Europe’s first commercial deep-space tracking services, compliment ESA’s own ESTRACK stations and provide deep-space tracking for both space agencies and private business.
• February 27, 2019: Satellite communications innovator and space gateway Goonhilly Earth Station has announced that it has inked a partnership agreement with the Australian Space Agency to collaborate and create new opportunities in the space economy in Australia, the UK and beyond. 33)
- The new statement of strategic intent and cooperation aims to help progress the Australian space sector and make the benefits of space more accessible for businesses, governments and institutions.
- One activity forming part of the agreement and already underway is Goonhilly's involvement in the proposed SmartSat CRC (Cooperative Research Center) space research initiative. This consortium aims to enhance connectivity, navigation and monitoring capability across Australia and to maximize the country's resources by solving major satellite system and advanced communications challenges.
- Another is Goonhilly's commitment to help develop Australian-based deep space communication assets. Goonhilly opened an office in Australia in 2018, run by industry veteran Bob Gough, and will invest further in infrastructure and facilities as part of its wider plan to support deep space projects globally.
- The partnership will also help to make the benefits of space more accessible for Australian businesses. For example, Goonhilly's Enterprise Zone status is unique in the space industry, offering businesses from Australia and beyond the chance to be part of a rich space ecosystem and to build a cost-effective European base from which to grow their business.
- To help accelerate the growth of the Australian space economy, Goonhilly is also adopting its tried and tested UK business model, which is built around the development of close working relationships with local and national government, academia, business and other industry players.
- Dr Megan Clark AC, Head of the Australian Space Agency said: "We welcome Goonhilly's intent to invest in communications, and research and development in Australia. The agreement will provide greater opportunities for technology transfer and the creation of local skilled jobs in the space sector."
- "Both Goonhilly and the Australian Space Agency have a shared commitment to increase the opportunities afforded by space exploration and development. Through this partnership we will enhance the capabilities and competitiveness of both Australian and UK industry, to forge productive international collaborations and promote investments in space," commented Ian Jones, CEO of Goonhilly.
- The two organizations share a common vision: to forge international collaborations and promote investments in space capabilities and capacities that help to accelerate the growth of the Australian space economy; to help improve the lives of all Australians through the development of innovative products and services; and to provide new opportunities by enhancing the capability and competitiveness of Australian industry.
• January 29, 2019: Goonhilly Earth Station has announced that data center industry veteran Chris Roberts has joined the company's executive team as Head of Data Center and Cloud. 34)
- Chris’s appointment comes as Goonhilly prepares to open a tier 3/4 data center in Spring 2019, offering exceptional connectivity by linking global subsea cables with satellite communications and fiber.
- Chris brings more than two decades’ experience in the data center and cloud hosting industry including senior roles at Pulsant, Datapipe and iomart. His expertise in building high-growth cloud hosting and data center businesses via a mix of direct and indirect channels will be invaluable in his new role.
- Goonhilly’s new high-specification data center’s use of renewables, its Enterprise Zone status and its low latency connections are designed to make it a cost-effective choice for hosting and co-location customers in the satellite and broadcast industries as well as a wide range of enterprises. A national infrastructure asset for many decades, the Goonhilly site offers customers a high level of resilience, enhanced by its rural location and a secure energy source including green power from its onsite solar farm and local wind generation.
• January 7, 2019: Satellite Applications Catapult, UK, and Infostellar of Tokyo, Japan, have signed a memorandum of understanding (MoU) to provide UK businesses with enhanced access to the Satellite Applications Catapult’s ground station in Goonhilly, Cornwall. 35)
- The Catapult’s ground station is the primary ground location for its In Orbit Demonstration (IOD) program, a unique service that supports UK business to achieve the launch of satellite data services. By integrating this ground station with Infostellar’s StellarStation service, organizations will be able to remotely access the Goonhilly station for uplink and downlink. The Catapult will also be able to share unused capacity with the StellarStation network to give greater access to their Goonhilly facility for UK companies.
- As a result of this collaboration, Infostellar plans to open a UK office at the Satellite Applications Catapult’s Harwell base in 2019. The UK office will focus on business development and regulatory affairs for Infostellar’s international expansion plans in Europe.
- With this agreement, the Satellite Applications Catapult continues to support innovative solutions for the small satellite community, as well as continuing to foster strong links between space companies in the UK and Japan.
• November 23, 2018: Satellite communications innovator and space gateway Goonhilly Earth Station has joined the consortium backing the SmartSat CRC (Cooperative Research Center), a proposed space research initiative which plans to drive the Australian space industry through satellite technologies and analytics. 36)
- Led by the University of South Australia (UniSA), Airbus Defence and Space and Australian defence sector engineering specialist Nova Systems, in partnership with the South Australian Space Industry Center, the proposed plan for the establishment of the SmartSat CRC was developed starting early in 2018 and has been submitted to the Australian government for ratification.
- The first stage of the application process with the Federal Government has been successfully completed and the consortium is now preparing the final stage application, and working on next steps outlining the organization's parameters and discussing funding.
- The SmartSat CRC consortium aims to enhance connectivity, navigation and monitoring capability for the benefit of Australia, helping to maximize its resources by solving major satellite system and advanced communications challenges. The goal is to catapult Australia's space industry into a leadership position in several areas including intelligent satellite systems, advanced communications, and earth observation driven data analytics.
- The research consortium aims to co-develop intellectual property and specialist industry expertise that will spawn new businesses, create economic value and generate new high-tech jobs in Australia. Other economic benefits include applying advanced space technologies and space related data to diverse areas of society and the economy, from agriculture and the environment to healthcare and disaster detection and management.
- The 67-member SmartSat CRC consortium also includes blue-chip industry leaders Harris Corporation, Thales Australia, BAE Systems, Dassault Systems and other space engineering companies as well as partnerships with NASA, JAXA and UK Catapult and University College London (UCL).
- Professor Andy Koronios, Dean of Industry and Enterprise at UniSA, said: "With its technological and commercial expertise, as well as its expanding capabilities and resources, we are confident that Goonhilly will make a significant contribution to the SmartSat CRC."
- Dr Bob Gough, Head of Business Development, Australia and Asia-Pacific at Goonhilly, commented, "The space industry is a global one and Goonhilly is well poised to support Australian organizations as they look to extend their reach. At our UK site we offer world-class satellite capacity with visibility spanning 145 degrees West to 135 degrees East. enabling our customers to reach millions of people and receive sites in a single satellite hop. This is complemented by our connectivity with bundles of subsea cables and fiber, and our new multi-million-dollar datacenter."
- "Establishing a technical and operational presence in Australia is essential for Goonhilly as we fulfil our goal to create a worldwide deep space network; joining the SmartSat CRC perfectly complements this objective. We are bringing our business model of cooperation and collaboration which has been so successful in the UK, and we will use this proven approach in our numerous SmartSat CRC projects."
- "With the global industry leaders and world-class university researchers in SmartSat CRC, there is huge potential to develop new space industry opportunities that benefit all of Australia and the broader Asia Pacific," Gough added.
- SmartSat CRC is determined to accelerate the nation's space industry momentum following the July 1st establishment of the Australian Space Agency, which was the launchpad for developing space-based opportunities to enhance businesses and communities.
• April 17, 2018: ESA has signed a collaboration agreement with Surrey Satellite Technology Ltd (SSTL) and Goonhilly Earth Station (GES) for Commercial Lunar Mission Support Services at the Space Symposium in Colorado Springs, USA. This innovative commercial partnership for exploration aims to develop a European lunar telecommunications and navigation infrastructure, including the delivery of payloads and nanosats to lunar orbit. 37)
- The partnership allows for a low-risk, phased approach to implementing a sustainable, long-term commercial service and will support lunar scientific and economic development across Europe and the rest of the world. The agreement includes the upgrade of the Goonhilly Earth Station for commercial deep space services and the development of the space segment with a lunar pathfinder mission. The cooperation also encompasses the commercial and regulatory support to catalyze the lunar economy and provide affordable access to the lunar environment, and ultimately deep space.
- The agreement was signed by Sir Martin Sweeting, founder and Executive Chairman of SSTL, Ian Jones, founder and Chief Executive of GES and David Parker, Director of Human and Robotic Exploration at ESA.
- David Parker commented, “The agreement between ESA and SSTL/GES establishes ESA’s first partnership for providing commercial services in support of lunar missions. The Lunar Pathfinder mission would provide exciting new opportunities for science and technology demonstration and open deep space access to new actors.”
- Following the recent announcement of the GES ground segment upgrade to form the world’s first deep space commercial node, the partners are now jointly committed to the developing the Lunar Pathfinder space segment for a low cost “Ride and Phone Home” capability. The Lunar Pathfinder mission will offer a ticket to lunar orbit for payloads and nanosats onboard an SSTL lunar mothership spacecraft, which will provide communications data relay and navigation services between customer payloads and the GES Deep Space ground station.
• October 19, 2018: Satellite communications innovator and space gateway Goonhilly Earth Station has opened an office at the Cody Technology Park in Farnborough, Hampshire, UK, in support of the firm's plans to expand their consultancy, design engineering and small-scale manufacturing capabilities — The new office is located at the Cody Technology Park, Farnborough, Hampshire GU14 0LX. 38)
- The new site gives Goonhilly more space to expand their design engineering team and attract talented engineers in the South-East and South-West of England who are keen to work at the forefront of the UK’s flourishing satellite communications sector. The teams in Farnborough and Goonhilly will collaborate closely.
- For example, while the Farnborough team will be focused on deep space antenna array design, their colleagues in Cornwall will undertake the implementation. Goonhilly is also recruiting and investing in small-scale advanced manufacturing/production facilities at their Cornwall headquarters, where it plans to build these next-generation systems.
Ultra-precise Navigation — Delta-DOR
When Cebreros (DSA 2), ESA's second deep-space antenna, entered operation in late 2005, the Agency could begin using 'delta-DOR', a powerful new navigation technique particularly important for interplanetary craft. The Cebreros station, DSA 2 (Deep Space Antenna 2), is located 77 km west of Madrid, Spain. It hosts a 35-meter antenna with transmission and reception in X-band and reception in Ka-band. It provides routine support to deep-space missions including Mars Express, Gaia and Rosetta. 39)
ESA's delta-DOR (delta - Differential One-way Range) system has already contributed to Venus Express' successful orbit insertion in April 2006 and to Rosetta's Mars swingby in February 2007, and will become a fundamental tool for navigating all of ESA's current and future interplanetary missions.
Background: Routine navigation of a spacecraft around the Solar System relies on two tracking methods: ranging and two-way Doppler.
Precisely measuring the time it takes radio signals to travel to and from a spacecraft gives the distance from the ground station ('two-way range'), while measuring the signal's Doppler shift (the shift in frequency due to relative movement between the transmitter and receiver) provides the craft's velocity along that line-of-sight ('range-rate').
The other two position coordinates, against the sky background, are obtained only indirectly from the motion of the ground station as the Earth rotates. These position components, though, can only be deduced to much lower accuracy. Usually, tracking over several days is necessary and this requires very high-fidelity modelling of the spacecraft's motion.
The tracking system at ESA's 35m deep-space stations, New Norcia (DSA 1) in Western Australia, Cebreros (DSA 2) near Madrid, and Malargüe (DSA 3), Argentina, provides very accurate measurements. Typically, the random errors on range are about 1 m and on the two-way range-rate less than 0.1 mm/s.
Nevertheless, the limitations described above mean the accuracy of resulting orbit determination may not be good enough for navigation during critical stages of a mission. This is especially the case on approaching a planet before landing, performing a swing-by or insertion into orbit.
Delta-DOR (delta - Differential One-way Range)
However, ESA can now augment conventional tracking by measurements using delta-DOR. NASA's Deep Space Network (DSN) has provided delta-DOR data since 1980 and has aided the navigation of ESA missions since 1986.
The delta-DOR technique for navigating interplanetary spacecraft is based on a simple but effective concept. Delta-DOR uses two widely separated antennas to simultaneously track a transmitting probe in order to measure the time difference (delay time) between signals arriving at the two stations. The technique of measuring this delay is named Differential One-way Range (DOR).
Theoretically, the delay depends only on the positions of the two antennas and the spacecraft. However, in reality, the delay is affected by several sources of error: for example, the radio waves travelling through the troposphere, ionosphere and solar plasma, and clock instabilities at the ground station.
Quasars: brightest beacons. Delta-DOR corrects these errors by tracking a quasar – an active galatic nucleus – that is seen in a direction close to the spacecraft for calibration. The chosen quasar's direction is already known extremely accurately through astronomical measurements, typically to better than 50 billionths of a degree (a nanoradian).
The quasar is usually within 10º of the spacecraft so that the two sources' signal paths through Earth's atmosphere are similar. In principle, the delay time of the quasar is subtracted from that of the spacecraft's to provide the ΔDOR measurement (the Greek symbol 'delta' is commonly used to denote 'difference'). The delay is converted to distance by multiplying by the speed of light.
A complication is that the quasar and spacecraft cannot be measured simultaneously. In practice, three scans are made: spacecraft-quasar-spacecraft or quasar-spacecraft-quasar, and then interpolation between the first and third converts them to the same time as the second measurement, from which the ΔDOR data point is calculated.
ΔDOR has been used with all ESA interplanetary spacecraft including Mars Express, Venus Express and Rosetta, and will be used with future missions such as Gaia.
Coordination of European Space Facility Activities
ESA and DLR Agree on Mission Control Coordination
• April 2, 2019: An existing deep-space dish antenna at the DLR Weilheim site, near Munich, may offer an almost-readymade solution to the problem of providing sufficient ground station capacity to support ESA’s current and future deep-space exploration missions. Now and in the next few years, ESA is sending some of the most advanced spacecraft ever flown to exotic locations like Mars, Mercury and Jupiter, and these missions all have one thing in common: they need plenty of ground station capacity to download their masses of science data and to enable mission controllers to send up commands. 40)
ESA already has three state-of-the-art ground tracking stations – identifiable by their big 35 m-diameter dish antennas – located in Australia, Spain and Argentina. These countries are located at longitudes about 120 degrees apart, so that the three stations can provide global coverage for missions voyaging in virtually any direction in our Solar System.
“The stations were built between 2002 and 2012, and their capacity in transmitting and receiving data will soon be reached, given the ambitious missions like BepiColombo, ExoMars and Juice now being implemented – and the fact that these newer spacecraft can all download tremendous amounts of science data,” says Pier Bargellini, responsible for the operation of ESA’s ground facilities.
With an eye to solving the challenge, engineers at ESA and DLR (German Aerospace Center) have begun assessing the possibility of using an existing 30 m-diameter dish antenna at Weilheim, 60 km south-west of Munich, to provide some add-on tracking capacity at the European longitude. This could solve part of the capacity problem on this continent while at the same time reusing existing European infrastructure and reducing the need for costly new construction.
DLR Weilheim features a number of dish antennas with varying sizes and the site is operated 24 hours/day to support near-Earth missions such as TerraSAR-X, TanDEM-X and GRACE Follow On controlled from DLR’s GSOC (German Space Operations Center) at Oberpfaffenhofen. The smaller antennas are also used to support ESA missions orbiting Earth, like Integral.
The 30m dish antenna supported ESA missions in the past, and is presently used when DLR supports partner agencies, such as downloading data from the Hayabusa-2 mission flown by JAXA of Japan. It has also recently been used to receive signals from global navigation satellites like GPS and Galileo.
A series of initial tests conducted by DLR and ESA engineers in the past few months proved that the dish and its sophisticated radio equipment could receive signals from current ESA missions, including Gaia and Mars Express.
“Since the 30m antenna was designed for solar and deep space missions, we are happy to see ESA’s interest in bringing it back to its original purpose,” says Rolf Kozlowski, head of the DLR Communications and Ground Stations department. “To integrate the antenna into the ESA network would be a challenging but rewarding task for DLR.”
“In addition to the reception functionality, the antenna could be upgraded to add transmission capabilities. Its overall characteristics makes it ideal to support missions at lunar distances or even missions to the Lagrange points.”
In addition to supporting future ESA and European missions, upgrading the dish would also enable DLR to expand its use for their own future missions or for those of partner agencies. Such cross-support arrangements are common in the field of spacecraft operations, and are typically done on an hour-for-hour exchange basis or in exchange for sharing a mission’s scientific data. Engineers from the two agencies will continue testing the Weilheim antenna, with the aim of proving its ability to begin serving as a functional communications backup for ESA missions like Gaia and Mars Express.
ESA and DLR signed cooperation agreement on 19 December 2018. Joint activities between ESA and national space agencies in the area of communications are excellent examples of how Europe can become even more capable and stronger by developing a ‘network of operational centers’. By linking the efforts of control centers operated by ESA and agencies like DLR, and their ground stations, resources can be shared – and European missions, industry and space ventures can benefit overall, making Europe even more competitive and attractive for international partnership in space. 41)
Hence, ESOC (European Space Operations Center) European in Darmstadt and the GSOC (German Space Operations Center) in Oberpfaffenhofen near Munich have agreed to exploit shared know-how in the fields of mission operations and ground-based infrastructure, jointly developing new concepts, technologies and procedures.
The cooperation agreement was signed on 18 December 2018 at DLR’s research center in Oberpfaffenhofen during an Interoperability Plenary meeting, which brought together representatives from 12 space agencies worldwide.
"Public space infrastructure should be used as effectively as possible. ESA therefore endeavors to establish a European network of competence centers. Close cooperation between ESOC and GSOC, as well as subsequent cooperation with other agencies and organizations, should strengthen Europe's position as a partner and competitor in the world market," explains Rolf Densing, ESA’s Director of Operations and Head of ESOC.
"We look forward to working with ESA to lay the groundwork for a European network of control centers,” says Hansjörg Dittus, DLR Executive Board member responsible for space research and technology.
Felix Huber, Director of DLR's Space Operations and Astronaut Training facility adds, "The German Space Operations Center can contribute its expertise in the preparation and execution of crewed and uncrewed missions, further strengthening Germany's position as a space nation in Europe".
The newly announced cooperation between ESOC and GSOC covers five areas: ground control systems, ground stations, space security and on-orbit servicing, post-International Space Station activities and crewed spaceflight, as well as general cooperation.
With respect to the development of ‘ground segments’ – the hardware, software and networks on ground used to operate and spacecraft in orbit – both control centers are already working on software for joint mission operations, the so-called European Ground Systems Common Core (EGS-CC).
Further planning includes a project to develop and set up a network of optical ground stations that will enable data transmission by laser. This will enable, for example, quantum keys to be transmitted to support secure communication in the future.
Mission Control 'Saves Science'
• May 17, 2019: Every minute, ESA’s Earth observation satellites gather dozens of gigabytes of data about our planet – enough information to fill the pages on a 100-meter long bookshelf. Flying in low-Earth orbits, these spacecraft are continuously taking the pulse of our planet, but it's teams on the ground at ESA’s Operations Center in Darmstadt, Germany, that keep our explorers afloat. 42)
From flying groups of spacecraft in complex formations to dodging space debris and navigating the ever-changing conditions in space known as space weather, ESA’s spacecraft operators ensure we continue to receive beautiful images and vital data on our changing planet.
Get in formation
Many Earth observation satellites travel in formation. For example, the Copernicus Sentinel-5P satellite follows behind the Suomi-NPP satellite (from the National Oceanic and Atmospheric Administration). Flying in a loose trailing formation, they observe parts of our planet in quick succession and monitor rapidly evolving situations. Together they can also cross-validate instruments on board as well as the data acquired.
ESA’s Earth Explorer Swarm satellites are another example of complex formation flying. On a mission to provide the best ever survey of Earth’s geomagnetic field, they are made up of three identical satellites flying in what is called a constellation formation.
Swarm’s individual satellites operate together under shared control in a synchronized manner, accomplishing the same objective of one giant – and more expensive – satellite.
“Formation flying has all the challenges of flying many single spacecraft, except with the added complexity that we need to maintain a regular distance between all of these high-speed and high-tech eyes on Earth,” explains Jose Morales Santiago, ESA’s Head of the Earth Observation Mission Operations Division.
Every decision we make, every command we send, has to be the right one for each spacecraft – particularly when it comes to maneuvers. These must be planned properly so that they do not endanger companion satellites, while keeping a consistent configuration across the formation.”
Last year, ESA’s Earth observation missions performed a total of 28 ‘collision avoidance maneuvers’. These maneuvers saw operators send the orders to a spacecraft to get out of the way of an oncoming piece of space debris.
An impact with a fast-moving piece of space junk has the potential to destroy an entire satellite and in the process create even more debris. As a spacecraft ‘swerves’ to avoid collision, science instruments may need to be turned off to ensure their safety and avoid being contaminated by the thrusting engine.
Teams at mission control consider how to keep Europe’s fleet of Earth observers safe while maximizing the vital work they are able to do. Recently, they came up with an ingenious concept to ‘save science’ during such maneuvers of the Sentinel-5P satellite.
The Sentinel team quickly realized that during a collision avoidance maneuver they would have to suspend science collection for almost a day, because of the emergency firing of the thrusters.
“That’s a lot of data to miss out on. As the amount of space debris is currently increasing, this would be something we would need to do more and more often,” explains Pierre Choukroun, Sentinel-5P Spacecraft Operations Engineer, who came up with the fix.
“So we designed and validated a new on-board function to enhance the spacecraft’s autonomy, such that the science data loss is reduced to a bare minimum. We are very much looking forward to securing more data for the science community in the near future!”
With this new strategy, the science instruments on Sentinel-5P would be shut off for around on hour compared with an entire day!
As if dodging bits of space debris weren’t enough for Europe’s Earth explorers, they also have to navigate the turbulent weather conditions in space.
Space weather refers to the environmental conditions around Earth due to the dynamic nature of our Sun. The constant mood swings of our star influence the functioning and reliability of our satellites in space, as well as infrastructure on the ground.
Figure 43: SOHO’s view of September 2017 solar flares. The Sun unleashed powerful solar flares on 6 September, one of which was the strongest in over a decade. An X2.2-class flare was launched at 09:10 GMT and an X9.3 flare was observed at 12:02 GMT. An M-class flare was also observed two days earlier on 4 September. The flares were launched from a group of sunspots classified as active region 2673. The images were captured by SOHO. The shaded disc at the center of the image is a mask in SOHO’s LASCO instrument that blocks out direct sunlight to allow study of the faint details in the Sun's corona. The white circle added within the disc shows the size and position of the visible Sun (video credit: ESA & NASA)
When the Sun is particularly active, it adds extra energy to Earth’s atmosphere, changing the density of the air at low-Earth orbits. Increased energy in the atmosphere means that satellites in this region experience more ‘drag’ – a force that acts in the opposite direction to the motion of the spacecraft, causing it to decrease in altitude.
Operators need this information to know when to perform maneuvers to “boost” the satellite’s speed in order to counter drag and keep it in its proper orbit.
This drag effect also changes the speed and position of space debris around Earth, meaning our understanding of the debris environment needs to be constantly updated in light of changing space weather.
While Earth observation satellites monitor the weather on Earth, we have to stay aware of the changing weather in space,” says Thomas Ormston, Spacecraft Operations Engineer at ESA.
“This is vital because understanding atmospheric drag is fundamental to predicting when we will be threatened by space debris and determining when and how big our spacecraft maneuvers need to be to keep delivering great science to our users.”
Space weather also impacts communication between ground stations and satellites due to changes in the upper atmosphere, the ionosphere, during solar events. Because of this, satellite operators avoid critical satellite operations like maneuvers or updates of the on board software during periods of high solar activity.
European Network of Operations Centers Takes Shape
• October 25, 2019: ESA and the French space agency CNES have signed an important agreement that will see the two agencies improve interoperability between their mission control facilities on ground, enhancing the abilities of each organization in space. 43)
The European ‘Network of Operations Centers’ will enable opportunities for joint action, knowledge sharing and technical interchange, and allow engineers and other professionals to benefit from crossed exchanges and mobility.
It will generate savings for European taxpayers through avoidance of duplication, and through optimization of existing capabilities and capacity on a wider European scale.
The role of any mission control center is to operate spacecraft in orbit, sending commands and downloading status information on the health and functioning of the satellite as well as the vital science data gathered by the craft’s instruments.
Training teams and building, operating and improving the mission control systems and ground stations needed to fly any mission is a complex process. Under the Network of Operations Centers initiative, Europe's institutional control centers are joining forces, with each benefitting from the expertise and capabilities available at the other while reducing risk and increasing synergies for all missions.
“By sharing our knowledge, ground infrastructure and technologies, we can drive innovation across all of our agencies for the benefit of Europe,'' says Rolf Densing, ESA’s Director of Operations.
“Joining forces means we can achieve together more than we could on our own, as we increase coordination, share operational tools and infrastructure and maximize the return on investment in ground systems and operations for Europe.”
ESA’s main mission control center is located in Darmstadt, Germany, while CNES’s is in Toulouse, France.
“This Memorandum of Cooperation marks a cornerstone for our agencies, as we develop our complementarity and face the challenges that lie ahead, together” says Frédéric Pradeilles, Director of Digital, Ground segments and Operations.
The two agencies have set a priority on cooperation across the full spectrum of ground systems engineering, from mission control and flight dynamics to laser-based optical communication and enhanced cooperation in the field of international technical standards.
By sharing some of the on-the-ground infrastructure, such as spacecraft tracking stations and antennas, agencies in the network of operations centers will enjoy increased robustness and redundancy in their ability to communicate with their spacecraft, reducing risk for costly missions.
The two agencies will also benefit from using engineering knowledge and data systems that can work together, improving interoperability.
The ESA-CNES agreement follows a similar agreement made between ESA and DLR, whose control center in Oberpfaffenhofen, near Munich, in December last year.
As much of the mission control hardware and software used by the three agencies is made in Europe, the network of operations centers effort will also boost opportunities and competitiveness on the world market for European high-tech industry.
The agreement was signed on 24 October 2019 at the IAC (International Astronautical Congress) in Washington DC, USA.
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. Comments and corrections to this article are always welcome for further updates (firstname.lastname@example.org).