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.
| Date of launch | 3 September 2020 |
| Mission Status | Operational (extended) |
| Swath (across-track) | 300 km |
| Orbit Height | 540 km |
| Orbit Type | Sun-synchronous |
| Orbit Period | 94 minutes |
| Inclination | 98° |
| Instruments | HyperScout-2 |
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.
| Attributes | HyperScout 2 | Justification |
| Field of view | 30° (ACT) x 15° (ALT) | Based on on-ground characterisation |
| Orbit height | 540 km | Based on satellite ADCS |
| Swath Across track | 300 km | Based on instrument field of view and orbit altitude |
| Ground sampling distance GSD (Across track) | 75 m | Based on instrument focal length and orbit altitude |
| Point Spread Function (PSF) | 2.0 px FWHM ACT 1.9 px FWHM ALT | Based on on-ground characterisation |
| Active sensor size | 4000 x 1850 px | The pixel dimension of the illuminated area of the sensor |
| Spectral Range | 450 - 950 nm | Assuming there is sufficient band width to downlink the entire acquisition |
| Spectral Resolution | 18 nm FWHM | Based on on-ground characterisation |
| Number of Bands | 50 | Depends on the acquisition scenario |
| Signal to noise ratio | 50 | Based on radiometric performance |
| Geometric accruacy | ~ 0.5 px average 0-3 px | Based on automatic keypoint comparison between HS and S2 imagery |
| Absolute Radiometric Accuracy | 10% | Based on comparison with coregistered S2 bands. |
| Bit Depth | 12 | Based 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.
Data
DATA DESCRIPTION
ESA offers registered users access, through a dedicated FTP server, to the following data collection: