IEEE Geoscience and Remote Sensing Magazine - December 2022 - 260

INSTRUMENTS AND MISSIONS
LARA FERNANDEZ
ADRIANO CAMPS , JOAN FRANCESC MUNOZ-MARTIN , JOAN ADRIÀ RUIZ-DE-AZUA ,
, ADRIAN PEREZ-PORTERO , DAVID LLAVERÍA , CHRISTOPH HERBERT ,
MIRIAM PABLOS , ALESSANDRO GOLKAR , ANTONIO GUTIÉRREZ, CARLOS ANTÓNIO,
JORGE BANDEIRAS, JORGE ANDRADE, DAVID CORDEIRO, SIMONE BRIATORE, NICOLA GARZANITI
,
FABIO NICHELE, RAFFAELE MOZZILLO, ALESSIO PIUMATTI, MARGHERITA CARDI, MARCO ESPOSITO,
CHRIS VAN DIJK, NATHAN VERCRUYSSEN, JOAO BARBOSA, JOHN HEFELE, RICK KOELEMAN,
BERNARDO CARNICERO DOMINGUEZ, MASSIMILIANO PASTENA
GIANCARLO FILIPPAZZO, AND AMANDA REAGAN
,
FSSCat: The Federated Satellite
Systems 3Cat Mission
Demonstrating the capabilities of CubeSats to monitor essential
climate variables of the water cycle
T
he Federated Satellite Systems/3Cat-5 (FSSCat) mission
was the winner of the European Space Agency
(ESA) Sentinel Small Satellite (S3) Challenge and overall
winner of the 2017 Copernicus Masters competition. It
consisted of two six-unit CubeSats. The Earth observation
payloads were 1) the Flexible Microwave Payload
2 (FMPL-2) onboard 3Cat-5/A, an L-band microwave
radiometer and GNSS reflectometer (GNSS-R) implemented
using a software-defined radio (SDR), and
2) the HyperScout-2 onboard 3Cat-5/B, a hyperspectral
camera, with the first experiment using artificial intelligence
to discard cloudy images. FSSCat was launched
on 3 September 2020 and injected into a 535-km synchronous
orbit. 3Cat-5/A was operated for three months
until the payload was probably damaged by a solar flare
and coronal mass ejection. During this time, all scientific
requirements were met, including the generation
of coarse-resolution and downscaled soil moisture (SM)
maps, sea ice extent (SIE) maps, concentration and thickness
maps, and even wind speed (WS) and sea surface
salinity (SSS) maps, which were not originally foreseen.
3Cat-5/B was operated a few more months until the number
of images acquired met the requirements. This article
briefly describes the FSSCat mission and the FMPL-2
payload and summarizes the main scientific results.
INTRODUCTION
The FSSCat mission was the winner of the 2017 ESA S3
Challenge and overall winner of the Copernicus Masters
competition. FSSCat was proposed by the Universitat
Politècnica de Catalunya (UPC), and it consisted of two
six-unit CubeSats, which were successfully launched on 3
September 2020 on the Vega Small Satellite Mission SerDigital
Object Identifier 10.1109/MGRS.2022.3219778
Date of current version: 23 January 2023
260
vice PoC, flight VV16. The two spacecraft, 3Cat-5/A [international
designation: 2020-061 W; North American
Aerospace Defense Command (NORAD) ID: 46292] and
3Cat-5/B (international designation: 2020-061X; NORAD
ID: 46293) were in a 97.4° inclination sun-synchronous
orbit, with a perigee of 535 km and an apogee of 538 km.
The mission's primary goals were the generation of 1)
coarse-resolution SM maps and SIE and thickness maps,
using L-band microwave radiometry and GNSS reflectometry;
2) downscaled SM maps, by combining passive
microwave and multispectral optical data; and 3) testing
communication techniques for future satellite federations.
Secondary goals were the generation of SSS and WS maps.
3Cat-5/A carried FMPL-2 [1], designed and implemented
by the UPC. FMPL-2 inherited the concept of the Passive Advance
Unit instrument, combining an L-band microwave radiometer
and a GNSS-R in a single instrument [2]. 3Cat-5/B
carried the HyperScout-2 hyperspectral imager, with a 31 #
16° field of view [3]. HyperScout-2 included two channels:
channel 1, in the visible and near infrared, with 4,000 #
1,850 pixels; 45 bands, from 400 to 1,000 nm; and a spectral
resolution of 16 nm, and channel 2, in the thermal infrared,
with 1,024 # 768 pixels; three bands, from 8 to 14 µm; and
spectral resolutions of 1,100 nm in the first two bands and
6,000 nm in the third one. HyperScout-2 had augmented
processing performance by using the PhiSat-1 board experiment,
featuring the new Myriad 2 artificial intelligence chip,
which improves data processing capabilities for hyperspectral
imagery [4]. In addition, both CubeSats included an
optical intersatellite link from Gölbriak Space, and an ultrahigh-frequency
intersatellite link demonstrator from the
UPC to test the concept of satellite federations.
Thanks to the background and previous experience
of the teams, this challenging mission was implemented
in just 1.5 years. In addition to the UPC and Gölbriak,
Deimos Engenharia was the prime contractor of the
IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE DECEMBER 2022

https://orcid.org/0000-0002-9514-4992 https://orcid.org/0000-0002-6441-6676 https://orcid.org/0000-0001-5892-3404 https://orcid.org/0000-0002-2108-5408 https://orcid.org/0000-0002-1223-6892 https://orcid.org/0000-0003-2736-1028 https://orcid.org/0000-0002-4917-5798 https://orcid.org/0000-0002-2578-8522 https://orcid.org/0000-0003-2694-7107 https://orcid.org/0000-0001-5993-2994 https://orcid.org/0000-0002-3289-8682 https://orcid.org/0000-0002-2108-5408

IEEE Geoscience and Remote Sensing Magazine - December 2022

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