FSSCAT is an innovative mission concept consisting of two federated 6U Cubesats in support of the Copernicus Land and Marine Environment services. The first CubeSat carries the Flexible Microwave Payload-2 (FMPL-2), a dual microwave payload (a GNSS-Reflectometer and an L-band radiometer with interference detection/mitigation), and the second one a hyper-spectral optical payload. The combined use of these payloads will allow to measure soil moisture, ice extent, and ice thickness, and to detect melting ponds over ice. FSSCAT also includes radio and optical inter-satellite links to test some of the techniques and technologies for the upcoming satellite federations. FSSCAT will be the precursor of a constellation of federated small satellites for Earth observation achieving high temporal resolution and moderate spatial resolution in a cost-effective manner.

The Federated Satellite Systems/ ³ Cat-5 (FSSCat) mission was the winner of the European Space Agency (ESA) Sentinel Small Satellite (S ³ ) 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 ³ Cat-5/A, an L-band microwave radiometer and GNSS reflectometer (GNSS-R) implemented using a softwaredefined radio (SDR), and 2) the HyperScout-2 onboard ³ Cat-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. ³ Cat-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. ³ Cat-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.

We present the preliminary results of our investigation on the effectiveness of the Serum methodology for Agile development of space hardware. We analyze the development process of a hardware payload that is part of a host nanosatellite mission composed of two 6U CubeSats (30cm x 20cm x 10cm). The host mission is a collaboration with several partners including academia and small and medium enterprises. Scrum is a product development process created as a faster, more effective way of developing software. The goal of our investigation is to understand whether and by how much the same Scrum principles that proved successful in software can be adopted vis-à-vis in hardware projects. We also intend to identify the fundamental challenges in such an approach for space missions. In the host mission, Scrum has been adopted for the development of the payload subject to the investigation. The paper introduces the ongoing development process and identifies Scrum-related challenges internal to the payload development and challenges related to the coordination of the process with partners adopting established development processes. The paper identifies opportunities of future work for the fine tuning of Agile development methodologies in space projects and illustrates key statistics that have been collected throughout the development so far.

Presently, the Earth Observation community is demanding applications that provide low latency and high downlink capabilities. An increase in downlink contacts becomes essential to meet these new requirements. The Federated Satellite Systems concept addresses this demand by promoting satellite collaborations to share unused downlink opportunities. These collaborations are established opportunistically and temporarily, posing multiple technology challenges to be implemented in-orbit. This work contributes to the definition of the Federation Deployment Control Protocol which formalizes a mechanism to fairly establish and manage these collaborations by employing a negotiation process between the satellites. Moreover, this manuscript presents the results of a validation campaign of this protocol with three stratospheric balloons. In summary, more than 27 federations with 63.0% of throughput were established during the field campaign. Some of these federations were used to download data to the ground, and others were established to balance data storage between balloons. These federations allowed also the extension of the coverage of a ground station with a federation that relayed data through a balloon, and the achievement of a hybrid scenario with one balloon forwarding data from a ground device. The results demonstrate that the proposed protocol is functional and ready to be embedded in a CubeSat mission.