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Satellite Missions Catalogue

ANSER (Advanced Nanosatellites System for Earth Observation Research)

Last updated:Dec 7, 2023




Launched in October 2023, the Advanced Nanosatellites System for Earth Observation Research (ANSER) is a constellation of three nanosatellites that monitor the water quality of swamps and reservoirs in Spain. The satellite is owned and operated by the Spanish Institute of Aerospace Technology (INTA) and also allows the study of global warming caused by greenhouse gases, particularly the accumulation of carbon dioxide, and the effect of solar radiation on the Earth.

Quick facts


Mission typeEO

Artist's rendition of ANSER constellation (Image credit: Alén Space)


Mission Capabilities

Both operational ANSER satellites carry the Cinclus photometer, a miniaturised hyperspectral camera that incorporates a micro spectrometer. 

Performance Specifications

The Cinclus photometer operates in five narrow bands in the red-infrared region, with a spatial resolution of 60 m and a swath width of 50 km.
Both ANSER Follower nanosatellites are in a sun synchronous polar orbit with an altitude of 500 km. The ANSER satellites fly in formation, spaced 10 km apart in orbit. The ANSER Leader satellite, planned to operate at the front of this formation, failed to deploy after launch, and was lost upon reentry.

Space and Hardware Components

All ANSER satellites use a 3U CubeSat bus, with a mass of 3.4 kg. The constellation is also being used to test an alternative passive control system, with each satellite bus equipped with adjustable fins or wings in lieu of a traditional in-orbit propulsion system. These fins make use of trace concentrations of gas at the orbit altitude to generate drag and lift, allowing for in orbit repositioning. The ANSER satellites also carry an Alen Space inter-satellite link (ISL), providing transmission of sensor data between satellites, and allowing the constellation to act as a single unit, with a single satellite transmitting to the ground stations.


The Advanced Nanosatellites System for Earth Observation Research (ANSER), as shown in Figure 1, is a constellation of three nanosatellites that aims to monitor water quality of swamps and reservoirs in Spain. The satellites are designated Leader, Follower-1 and Follower-2. The constellation was launched on October 9, 2023 and remains operational despite the loss of the lead satellite after it failed to deploy after launch. The Spanish Institute of Aerospace Technology (INTA) owns and operates the mission, which also allows the study of global warming caused by greenhouse gases, particularly the accumulation of carbon dioxide, and the effect of solar radiation on the Earth. The constellation’s satellites fly in a close formation, about 10 km apart, allowing them to function as a single unit.

Figure 1: ANSER Follower Nanosatellite (Image Credit: INTA)


The ANSER satellites use identical cubesat buses, with a 3U form factor. Each nanosatellite weighs 3.4 kg, with dimensions 10 cm x 10 cm x 34.5 cm. The ANSER mission is also being used to test a novel method of in-orbit manoeuvring, forgoing traditional propulsion systems for a pair of bus-mounted fins, known as a passive control system. This system uses Earth’s minimal atmosphere at the orbit altitude of 500 km to generate drag and lift, using a specialised set of algorithms, known as ‘Differential drag and lift’ manoeuvres, to determine the angle of each fin. Increasing the drag effect allows significant relative movements along track, while the lift effect is capable of producing small cross-track shifts. On average, the ‘wings’ can produce up to 10 km of along track separation in 72 hours. The constellation uses distributed attitude control across nanosatellites, preventing the disorientation of any units.


The ANSER constellation was launched on October 6, 2023, aboard an Arianespace rideshare mission, using the Vega VV23 rocket. However, the ANSER-Leader nanosatellite failed to deploy, reentering the atmosphere. ANSER-Follower 1 and 2 remain operational, at an altitude of 500 km and in a sun-synchronous polar orbit, flying in formation with a distance of 10 km between each satellite. Due to the satellites’ passive control system, their orbit will degrade in two to three years, allowing for the program to be updated.

Mission Status

  • October 10, 2023: ANSER Leader’s failure to deploy is confirmed based on unsuccessful efforts to contact the satellite, and NORAD data indicating only 10 of 12 expected objects launched on the Vega VV23 rocket are in orbit.
  • October 9, 2023: The three ANSER nanosatellites successfully launch aboard the Arianespace Vega VV23 rocket, however, launcher telemetry for neither the ANSER Leader cubesat nor the Estonian ESTCube-2 is received, indicating a likely deployment failure.
  • September 4, 2017: INTA announces the ANSER project and funding for a constellation of three nanosatellites, intended as a successor to the Optical Nanosatellite (OPTOS)

Sensor Complement


Cinclus, the primary instrument of the ANSER series carried by the ‘Follower’ satellites, is a complementary metal oxide semiconductor (CMOS) based imaging photometer. This instrument allows remote sensing of inland continental waters, imaging in five narrow spectral bands in the red-infrared range. Cinclus will detect chlorophyll and phycocyanin concentrations in inland Iberian lakes and reservoirs. The collection of this data assists with the study of both pollution levels in water sources, and in the detection of potentially hazardous microorganism growths, such as phytoplankton or algal blooms, vital elements of determining water quality. The instrument is a fractionated payload, distributed across the ANSER constellation, with the leader satellite carrying a panchromatic camera for cloud detection and pre-validation of hyperspectral data collected. The two ANSER followers each carry miniaturised hyperspectral cameras incorporating micro spectrometers, providing 60 m spatial resolution with a swath width of 50 km. Each follower satellite will also have near constant and sun-glint free observation angles, due to the 9° field of view and westward tilting. Cinclus is constructed using CMOS elements, rather than the traditional charge coupled device (CCD) components used in most photometers. While both CMOS and CCD devices use photodiodes to collect optical imagery, a CMOS system has both a photodiode and a CMOS transistor for each pixel, while CCD imagers use an array of capacitors, whereby a control circuit causes each capacitor to transfer its contents to its neighbour, and the last capacitor in the array dumps its charge into a charge amplifier. As seen in Figure 2, the matrix of switches deployed in CMOS imagers allows pixel signals to be amplified individually, and accessed directly and sequentially, offering lower power consumption and faster processing.

Figure 2- Photodiodes of a CCD and CMOS imager (Image Credit: Automated Imaging Association)

Ground Segment

Prior to the loss of ANSER Leader in launch, the constellation was to use Alen Space’s inter-satellite link (ISL), with the Follower cubesats transmitting Cinclus data to the Leader satellite, which would then be relayed to ground stations, with the constellation essentially operating as a single unit. Despite the loss of ANSER Leader in deployment, the remaining ANSER satellites will continue to operate in a similar manner, using the onboard ISL to share data to be collectively transmitted to ground stations. This ISL system operates in a 401-402 MHz radio frequency, and can be optimised for transmission distances up to 90 km greater than the constellation’s 10 km spaced formation through modulation of its power and bit rate.


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