QPS-SAR (Q-shu Pioneers of Space - Synthetic Aperture Radar) Constellation

Quick facts

Overview

Summary

Mission Capabilities

Each QPS-SAR satellite carries a deployable 3.6 m X-band SAR antenna that facilitates high resolution ground observations 24 hours a day, regardless of weather conditions, supporting the rapid acquisition of imagery in crises like natural disasters. The full constellation will provide a near-real time data provisioning service, enabling the observations of almost anywhere on Earth at an average interval of ten minutes. 

iQPS also plans to demonstrate feasibility for low-cost SAR satellites that can be deployed into a large constellation to enable global measurements.

Performance Specifications

QPS-SAR gathers imagery in two modes: stripmap mode, which prioritises observation width, and spotlight mode, which prioritises resolution. Stripmap achieves a 1.8 m spatial resolution while spotlight achieves 0.47 m, at the cost of a smaller field of view. The 9.38 GHz (X-band) antenna has a bandwidth of approximately 600 MHz, 2 kW of peak radiating power, and is capable of multiple imaging directions.
The QPS-SAR constellation will operate with 36 satellites in four different orbits, with nine satellites in each orbit in order to achieve a ten minute repeat cycle globally. The satellites will achieve high temporal resolution through non sun-synchronous inclined orbits, as the SAR satellites do not require illumination from the Sun to collect imagery.

Space and Hardware Components

Each QPS-SAR satellite has a mass on the order of 100 kg and are powered by body-mounted solar panels. Electric propulsion thrusters facilitate orbit maintenance and end of life de-orbiting manoeuvres. The constellation will utilise Geostationary orbiting satellites to establish an inter-satellite communication system for the rapid tasking and downlink of SAR imagery. 
Each spacecraft houses a spring loaded antenna that unfolds in orbit to a seamless bowl-shape 3.6 m in diameter, as well as a sub-millimetre space debris sensor, which aims to quantify the density of debris in low-Earth orbit (LEO).
 

Overview

QPS-SAR of the Institute for Q-shu Pioneers of Space, Inc. (iQPS) is a synthetic aperture radar (SAR) imaging satellite constellation planned to house 36 high resolution satellites that will provide high resolution and quality near real-time SAR imagery. 1)

SAR is a fundamental radar imaging technology in which targets are observed by transmitting an electromagnetic signal and measuring the properties of the reflected signal. Unlike passive remote sensing systems like traditional optical imaging, SAR is an active system that does not rely on unobstructed reflected light, making observations possible through the cover of night and clouds. The measurement of natural disasters such as flood, earthquakes or volcanic eruptions by optical imagery can be impeded by cloud cover, while SAR imaging can provide high resolution imagery in response to any situation irrespective of illumination. Moreover, employing multiple satellite passes, interferometric SAR (InSAR) can be used to detect slight movements of the Earth’s surface, offering capability for the extensive monitoring of essential infrastructure like roads and buildings. 2)

iQPS is a Japanese private space agency involved in the research and development, design, manufacture, sales, operation, and maintenance of satellites and related systems. The company plans to have 24 satellites in the QPS-SAR constellation by 2027. The full constellation of 36 will provide a “near real-time data provisioning service, enabling the observation of almost anywhere on Earth at an average interval of ten minutes. iQPS plans to address the typically large masses of existing SAR satellites, reducing costs and enabling the deployment of a large constellation with global coverage capacity. 1)

Due to its geography, Japan is a natural disaster-prone country, constantly exposed to risks such as earthquakes, typhoons, heavy rain, floods, and volcanic eruptions. In cases of poor or severe weather, conventional optical imaging satellites have their line of sight with the ground obscured by clouds. However, the QPS-SAR constellation will be able to rapidly make ground observations 24 hours a day, regardless of the weather. 2)

Paired with AI, iQPS plans to use SAR observations to predict regional economic changes based on traffic conditions; future produce values based on growth conditions; city-wide security systems comprised of satellite observations and ground cameras; and to support the realisation of autonomous driving by predicting optimal traffic routes and risks based on vehicle and human behaviour patterns, and changes in buildings. 2)

Spacecraft

In order for QPS-SAR to achieve high resolution SAR imagery while keeping the satellite mass within the 100 kg range, iQPS developed an innovative lightweight antenna that can be deployed in orbit. The QPS-SAR satellites hold sub-metre imaging resolution as well as one-twentieth the mass and one-hundredth the cost of conventional SAR satellites. iQPS’ patented antenna measures 0.8 m in diameter and 0.15 m in height when stowed, and unfolds to achieve a 3.6 m diameter. The antenna expands with a spring-loaded design into a seamless bowl shape capable of strong radio emission. 3)

From the third QPS-SAR satellite and onwards, the constellation’s satellites house the on-orbit imaging device called FLIP (Fast L1 Processor), which, with the help of AI, enables the high-speed distribution of data after observations. This makes it possible for the continuous imagery acquisition of stationary (e.g. land and buildings) and moving objects (e.g. cars, ships, people, and livestock). FLIP is a joint development between the Japanese Aerospace Exploration Agency (JAXA) and Alouette Technology. 2)

The satellites house solar electric propulsion thrusters, intended to maintain the spacecrafts’ orbits and complete de-orbiting manoeuvres after mission completion. Using geostationary satellites, an inter-satellite communication system will be used for rapid tasking and imagery downlink.

The QPS-SAR satellites also house a debris sensor, designed to quantify space debris in low-Earth orbit (LEO). The sensor was developed jointly by iQPS and IHI Corporation. iQPS set out to investigate the density of space debris smaller than 1 mm in size, as it can have devastating effects on spacecraft with no internationally agreed upon quantification.  3)

The debris sensor operates with an array of thin wires with electricity flowing through them, which when impacted by space debris would cut the wires. The number of wires without current flowing through them reveal the size of the debris. Tetsuo Yasaka, Founder of iQPS, believes that “the simpler the principle, the more practical it can be”.

Launch

QPS-SAR No.1

QPS-SAR No.1 ‘Izanagi’ was launched on December 11th, 2019 at 09:55 UTC from the Satish Dhawan Space Center, India, by the Indian Space Research Organisation (ISRO) on their Polar Satellite Launch Vehicle (PSLV).

QPS-SAR No.2

QPS-SAR No.2 ‘Izanami’, an improvement to its predecessor Izanagi, was launched on January 25th, 2021 at 15:00 UTC from Cape Canaveral, United States, by SpaceX onboard a Falcon 9 rocket. Ianami was launched into an orbit of approximately 525 km.

iQPS was launched with SpaceX’s first RideShare mission, named Transporter-1, alongside 142 other small satellites.

QPS-SAR No.3 and No.4

QPS-SAR No.3 ‘Amateru-I’ and No.4 ‘Amateru-II’ were launched on October 12th 2022 at 00:50 UTC from the Uchinoura Space Centre, Japan, by JAXA onboard Epsilon Rocket 6. Shortly after launch, an issue with the launcher’s third stage separation resulted in the deviation of trajectory. A destruction command signal was sent to the rocket, and the satellites were lost.

QPS-SAR No.6

QPS-SAR No.6 ‘Amateru-III’ was launched on June 12th, 2023 at 21:35 UTC from the Vandenberg Air Force Base, United States, by the SpaceX Falcon 9 Transporter-8 mission. Amateru-III was inserted into an orbit of approximately 540 km in altitude 79 minutes after launch.

QPS-SAR No.5

QPS-SAR No.5 ‘Tsukuyomi-I’ successfully launched on December 15th, 2023 from the Onenui Station, New Zeakand at 4:05 UTC onboard an Electron KS launcher of Rocket Lab. The satellite was placed into an orbit with an approximate altitude of 575 km inclined at 42°. QPS-SAR No.5 passes over the same location five or six times a day in equatorial latitudes, which is critical for iQPS’ goal of providing near-real time data provision from the QPS-SAR constellation.

QPS-SAR No.7

QPS-SAR No.7 ‘Tsukuyomi-II’ was launched onboard Space-X’s first Bandwagon rideshare mission on April 7th, 2024 at 23:16 UTC on board a Falcon 9 from Cape Canaveral. The satellite was placed into an orbit with an altitude of 590 km and inclination of 45°. QPS confirmed communication with the satellite was established an hour later, and all equipment was working properly.

Orbit

The QPS-SAR constellation will operate with 36 satellites spread around the Earth in four different orbits, with nine satellites in each orbit. With this configuration, iQPS will achieve a revisit time within ten minutes on average. 2)

Mission Status

• 1st February 2024: iQPS releases imagery from QPS-SAR No.5 ‘Tsukuyomi-I’ from its high resolution spotlight imaging mode. This imagery has a resolution of 0.46 m x 0.45 m, and highlights minute detail in complex topographies. Off-nadir viewing from the satellites adds depth to the imagery, providing insight into the elevation of infrastructure and landscapes.

• 17th January 2024: iQPS releases first light imagery from QPS-SAR No.5. Following a month of calibration, the satellite successfully acquires imagery in stripmap mode and will further enhance image quality through fine-tuned attitude control and imaging modes.

The first light imagery of QPS-SAR No.5 were all acquired through cloudy weather conditions, demonstrating the incredible versatility of SAR imagery with its ability to make observations 24/7 in any conditions. First light imagery was made whilst gradually increasing the power output of the SAR instrument, with Hiroshima observed using the satellite’s steady-state output, Wajima-shi observed at half power output, and Kitakyushu at one quarter of its output. 5)

• 15th December 2023: QPS-SAR No.6, nicknamed ‘Tsukuyomi-I’ or ‘the Moon God Awakens’ launches on an Electron KS launcher of Rocket Lab, following delays in which iQPS replaced the satellite’s launch provider in Q2 2023. 4)
• 13th July 2023: iQPS announce QPS-SAR No.6’s successful acquisition of first light imagery, which became the highest resolution commercial SAR imagery over Japan (0.46 m), previously held by QPS-SAR No.2 (0.7 m).

• 12th June 2023: QPS-SAR No.6 launched onboard the SpaceX Transporter-8 mission. On the same day as the satellite launched, Amateru-III’s first communications were established and its antenna deployed. QPS-SAR No.5 was planned to launch before No.6 in January 2023, but its launch was rescheduled following circumstances with the contracted launch vehicle provider.

• 12th October 2022: QPS-SAR No.3 ‘Amateru-I’ and No.4 ‘Amateru-II’ are launched by JAXA onboard the Epsilon rocket 6 from the Uchinoura Space Center in Japan. An issue in the rocket’s third stage separation resulted in the unfortunate loss of the two satellites.

• 13th May 2021: Izanami acquires the highest resolution imagery of Japan from a SAR satellite, with a resolution of 70 cm.
• 3rd March 2021: iQPS announce the successful acquisition of first light imagery from QPS-SAR.
• 30th January 2021: Izanami’s antenna is deployed in orbit, and its commissioning phase begins.
• 25th January 2021: First contact with Izanami is successfully made the day after launch.
• 25th January 2021: SpaceX launch QPS-SAR No.2 ‘Izanami’ is successfully launched by SpaceX on a Falcon 9 rocket from Cape Canaveral, Florida.
• 18th December 2019: SAR operation of Izanagi begins, and the satellite confirms that 95% of its functions are operational. Defects in the satellite’s operation were shortly discovered which ultimately prevented the deliverance of SAR data.
• 16th December 2019: Izanagi’s antenna successfully deploys in orbit.
• 12th December 2019: First contact with Izanagi was achieved following the successful launch.
• 11th December 2019: The first satellite of the constellation, QPS-SAR No.1, nicknamed ‘Izanagi’, was successfully launched by ISRO on the PSLV rocket.

Sensor Complement

The primary instrument onboard QPS-SAR is a 3.6 m radio antenna that unfolds once deployed in orbit. From the development of the third SAR satellite and onwards, the satellites are equipped with an upgraded antenna capable of acquiring SAR imagery with a spatial resolution of 46 cm.

iQPS offers two observation modes for QPS-SAR, stripmap mode, which prioritises observation width, and spotlight mode, which prioritises resolution. Stripmap achieves a 1.8 m spatial resolution while spotlight achieves 0.47 m, at the cost of a smaller field of view.

Ground Segment

iQPS developed a console to facilitate rapid tasking of QPS-SAR imagery and for accessing archived data. The console offers observation selection, tasking execution, data downloading and API integration.

References  

1) “Institute for Q-shu Pioneers of Space, Inc. (iQPS),” URL: https://i-qps.net/en/

2) “Satellite Specifications,” iQPS, URL: https://i-qps.net/en/product/

3) “QPS-SAR Project” https://i-qps.net/en/project/

4) Derek Goddard, “Rocket Lab Electron successfully returns to flight with launch of QPS-SAR 5,” Seradata, December 15, 2023, URL: https://www.seradata.com/rocket-lab-electron-makes-successful-return-to-flight-with-electron-launch/

5) “QPS-SAR-5 TSUKUYOMI-I’s First Light Images,” iQPS, January 17, 2024, URL: https://i-qps.net/en/news/1756/