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About FSSCat

FSSCat is a ground-breaking mission concept that consists of two federated 6U CubeSats which operate in support of the Copernicus Land and Marine Environment services.

As a precursor to a constellation of federated small satellites for Earth Observation, FSSCat is equipped with a multi-spectral optical payload and a dual microwave payload, including a GNSS-Reflectometer and an L-band radiometer with interference detection/mitigation capabilities. FSSCat is capable of measuring soil moisture, ice extent, and ice thickness, and detecting melting ponds on ice. Additionally, the satellites feature radio/optical and Iridium inter-satellite links to evaluate key technologies and techniques for future satellite federations.

Mission Parameters
Date of launch3 September 2020
Mission StatusOperational (extended)
Swath (across-track)300 km
Orbit Height540 km
Orbit TypeSun-synchronous
Orbit Period94 minutes

FSSCat Objectives

The primary objective of the FSSCat mission is to gather, in a cost-effective manner, data which supplements the information provided by the Copernicus Sentinels, with a focus on supporting the Copernicus Land and Marine Environment services.

In achieving this goal, FSSCat aims to deliver, via its optical and microwave payloads, data at a high temporal resolution with a moderate spatial resolution. Additionally, the mission aims to demonstrate Inter-Satellite Links (ISL) through the use of its Laser Communication Payload.

FSSCat Instruments


FSSCat carries HyperScout-2 onboard which is a compact hyperspectral VNIR (Visible and Near Infrared) imager and multispectral (MS) Thermal Infrared (TIR) imager with a wide swath and powerful processing abilities. An artificial intelligence (AI) chip carried by the satellite allows AI processing algorithms to be directly applied to acquired data while onboard, enabling the production of Level-1C hyperspectral data in-orbit.

AI is also leveraged to select which data to be downloaded based on the cloud coverage of the acquired scene, an ability that is of particular benefit given the large volume of data generated by Earth observation hyperspectral imaging missions.

The microwave payload (FMPL-2) combines a GNSS-Reflectometer and an L-band Radiometer to perform sea-ice detection and thickness monitoring, and soil moisture measurements, which may complement data from HyperScout-2.

Characteristics of the L-1C VNIR TOA reflectance hyperspectral cube
AttributesHyperScout 2Justification
Field of view30° (ACT) x 15° (ALT)Based on on-ground characterisation
Orbit height540 kmBased on satellite ADCS
Swath Across track300 kmBased on instrument field of view and orbit altitude
Ground sampling distance GSD (Across track)75 mBased on instrument focal length and orbit altitude
Point Spread Function (PSF)2.0 px FWHM ACT 1.9 px FWHM ALTBased on on-ground characterisation
Active sensor size4000 x 1850 pxThe pixel dimension of the illuminated area of the sensor
Spectral Range450 - 950 nmAssuming there is sufficient band width to downlink the entire acquisition
Spectral Resolution18 nm FWHMBased on on-ground characterisation
Number of Bands50Depends on the acquisition scenario
Signal to noise ratio50Based on radiometric performance
Geometric accruacy~ 0.5 px average 0-3 pxBased on automatic keypoint comparison between HS and S2 imagery
Absolute Radiometric Accuracy10%Based on comparison with coregistered S2 bands.
Bit Depth12Based on sensor and electronics design

The alignment accuracy of the data cubes is quantized using automatic keypoint detection methods provided by the OpenCV library. On average, the resulting interband accuracy is less than a half a pixel. However, because the georeferencing relies solely on visual data, the accuracy is generally lower on homogeneous landscapes where there are less distinct features to align on.

The radiometric accuracy of the HyperScout VNIR data is determined through comparison with Sentinel-2’s L-1C data products. The spectral bands of HyperScout are aggregated to match the band responses of Sentinel-2. To minimise the effect of co-registration errors and differences in contrast (MTF) on the validation of the radiometric quality, pixels binned to 10x10 tiles are compared.



ESA offers registered users access, through a dedicated FTP server, to the following data collection:



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