ESA's Earth Observation Programme Board has unanimously approved the integration of the Federated Satellite Systems (FSSCat) mission, the Geostationary Environment Monitoring Spectrometer (GEMS) instrument on-board the GEO-KOMPSAT-2B satellite and the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission, as Third Party Missions (TPMs) within the framework of the ESA Earthnet programme.

The three initiatives were chosen due to the missions contribution to long-term science exploitation, data continuity and their synergy with existing ESA missions and other missions already part of the TPM scheme. GEMS and GRACE-FO in particular also support international initiatives, cooperation across multiple space agencies and future missions.

FSSCat, GEMS and GRACE-FO will be added to ESA's TPM portfolio as part of the Earthnet programme for the 2020-2022 timeframe. All data will be made available to the general public, with a free and open data policy.

FSSCat: Bringing AI to TPMs

The FSSCat 6U tandem mission for sea ice and soil moisture monitoring won the first Sentinel Small Sat Challenge of the 2017 Copernicus Masters. It was conceived and proposed by a joint team from Spain's Universitat Politècnica de Catalunya (UPC), in Barcelona, and the Estonian start-up Golbriak Space OÜ.

FSSCat consists of two federated 6-Unit Cubesats that carry two instruments each. The first is the Flexible Microwave Payload version 2 (FMPL-2), made up of a Global Navigation Satellite Systems (GNSS) reflectometer and a L-band radiometer with interference detection/mitigation that maps ice over the polar region, measures ice thickness and detects melting ponds over ice. The second is HyperScout-2, a hyper-spectral optical payload, that helps monitor, among others, fires, oil spills and water quality. The combined use of the two main payloads also allows for the measurement of soil moisture, using a technique called pixel downscaling.

The second satellite of the FSSCat mission, dubbed Ф-sat-1, is Europe's first artificial intelligence Earth observation satellite. It is an experiment to improve the efficiency of sending vast quantities of hyperspectral data back to Earth, by filtering out cloudy data.

The ɸ-sat-1 experiment includes the first deep Convolutional Neural Network (deep CNN) in space, performing near-real-time inference thanks to a highly efficient off-the-shelf Myriad AI chip, which enables enhanced cloud detection and removal from hyperspectral imagery. ɸ-sat-1 was developed by a consortium led by COSINE, which also included Synergize and the University of Pisa.

As a Third Party Mission, FSSCat will provide useful data to monitor polar ice, snow and soil moisture, and to perform terrain classification and terrain change detection. The products derived from FMLP-2 and HyperScout-2 also complement products generated by other ESA and Copernicus Sentinel missions. The ɸ-sat-1 experiment meanwhile represents a first for ESA and paves the way for the development of future missions with AI on-board.

The Earthnet programme will allow to facilitate the full research and science exploitation of the mission and its innovative artificial intelligent on-board capacity.

GEMS: Towards a Global Understanding of Pollution

South Korea's Geostationary Environment Monitoring Spectrometer (GEMS) instrument, on the Korean Aerospace Research Institute (KARI) GEO-KOMPSAT-2B satellite, is a geostationary scanning ultraviolet-visible spectrometer, designed to monitor trans-boundary pollution events for the Korean peninsula and the Asia-Pacific region.

The mission was launched on 18 February 2020, by Ariane 5 from Guiana Space Center. The spectrometer provides high spatial and high temporal resolution measurements of ozone, its precursors, and aerosols. The satellite is part of the KARI programme, funded by the Korea Ministry of Environment (MOE) and supported by the National Institute of Environmental Research (NIER).

GEMS is the first of three instruments that will be part of the Committee on Earth Observation Satellites (CEOS) atmospheric geostationary virtual constellation, which will revolutionise the way scientists observe air quality over the Northern Hemisphere. It will also contribute to the understanding of the globalisation of pollution events, source/sink identification, and long-range transport of pollutants.

As part of the TPM scheme, Earthnet will support data quality assessment, data characterisation, cal/val and cross-calibration activities, in a multi-mission scenario in symbiosis with other ESA and atmospheric Copernicus Sentinel missions and the future NASA TEMPO mission.

This support will also allow product and methodologies harmonisation, facilitate future applications and interoperability across missions, to foster synergies and build Cal/Val capacity and knowledge for the European scientific community.

GRACE-FO: Ensuring Mass Change Data Continuity

Mass change is a fundamental climate system indicator and provides an integrated global view of how Earth's water cycle and energy balance are evolving. The GRACE-FO mission was launched in 2018, to continue the observation of mass change in the Earth system of the original GRACE mission (2002-2017), founded on highly precise microwave-based satellite-to-satellite tracking (SST).

GRACE and GRACE-FO monitor changes in ice sheets and glaciers, near-surface and underground water storage, as well as changes in sea level and ocean currents, on a monthly basis. GRACE and GRACE-FO were both implemented under US-German partnership.

GRACE was supported by the TPM scheme at the end of its mission lifetime to narrow the gap towards GRACE-FO as much as possible. GRACE-FO now needs to be operated as long as possible to continue mass change data based services, to obtain reliable statistics and a better understanding of how anthropogenic climate change and natural climatic cycles interact, while narrowing the gap as much as possible, or even achieving an overlap with the joint ESA/NASA Next Generation Gravity Mission (NGGM).

The inclusion of the GRACE-FO mission in the ESA TPM portfolio will enable focused key investigations and supplementary operations, which are synergistically addressed by GRACE-FO and the ESA/NASA NGGM joint constellation, paving the way for long-term science exploitation.