OHB wins ESA contract for a study to implement radar-based Earth observation from geosynchronous orbit

Bremen, November 12, 2019. OHB System AG, a subsidiary of space and technology group OHB SE, has been selected by the European Space Agency ESA as prime contractor for a feasibility study concerning the implementation of a radar-based Earth observation mission from a geosynchronous orbit. Known as “Hydroterra” (formerly G-Class), the project is a candidate for the tenth mission in ESA’s Earth Explorer program. By observing hydrological cycles over Africa and Europe, Hydroterra will allow the prediction of extreme rainfall and associated flooding at an earlier stage. The Phase 0 study has an order value of EUR 1 million.

Mission proposals from researchers

Humanity is confronted with an increasing threat from climate change. The Earth Explorer missions are part of ESA's Living Planet program and aim to provide high-quality remote sensing data for surveying the Earth. To date, five satellites have been launched within the program and four more are currently under development. The satellites already in orbit collect data on the Earth's gravitational field, soil moisture and salinity of the oceans, the planetary ice masses, the Earth's magnetic field and the dynamics of the Earth's atmosphere. Proposals for further satellite missions come directly from the scientific community and thus reflect current research priorities in environmental sciences. The idea for the Hydroterra mission came from a team of European scientists led by Cranfield University.

Hydroterra could save lives

Large parts of Africa and the entire Mediterranean region are often afflicted by droughts alternating with heavy rainfall. Just a few weeks ago, several people died in violent storms in southeastern Spain. It is hoped that in the future the Hydroterra mission will enable such extreme weather situations to be predicted at an earlier stage. To this end, the satellite will be fitted with a synthetic aperture radar (SAR) and placed in a geosynchronous orbit. The SAR permits an analysis of the water content in the soil and the atmosphere, while the positioning in a geosynchronous orbit ensures continuous observation of the selected regions. So far, this combination of payload and orbit has not been implemented in any mission. “Obtaining a viable signal from a distance of almost 36,000 kilometers through the distorting effects of the atmosphere requires a great deal of technical expertise,” says Ann-Theres Schulz, head of the Hydroterra project at OHB, explaining the special challenge to be addressed. At the same time, she also emphasizes the scientific findings that can be gained with Hydroterra: “Hydroterra is a fascinating project. Once the satellite is in orbit, we can study the development of storms and extreme rainfall in detail.”

The project is currently in Phase 0, the definition phase, which will run until November 2020. The purpose of this phase is to demonstrate the feasibility of the mission. As prime contractor, OHB is leading a consortium of subcontractors consisting of Thales Alenia Space Italia, Elecnor Deimos, Telespazio VEGA UK and Aresys and is responsible for the design of the overall system and the satellite platform as well as for the overall performance. At the same time, Cranfield University and its partners will further concretize the scientific concept.

Three candidates for the tenth Earth Explorer

Apart from Hydroterra, there are two other candidate missions for the tenth Earth Explorer:

Harmony (formerly Stereoid) is a radar mission for the observation of ocean currents, movements of ice masses and topographical changes of the Earth’s surface. For this mission, OHB System AG, in cooperation with its sister company OHB Sweden AB, is responsible for designing the satellite platform and the optical instrument.

The Daedalus satellite, on the other hand, is to carry several different instruments to study electrodynamic processes in the upper atmosphere, an area which has which has hardly been researched so far. OHB System AG is the prime contractor for the payload module, which is being developed in cooperation with a consortium of subcontractors.

A Phase 0 study is being carried out simultaneously for all three candidate missions. After the presentation of the results in November 2020, one of the mission plans will be discarded, while work on the two remaining candidates will enter Phase A, the design phase. A decision on which mission will ultimately make it to implementation will be made in 2022 after the completion of Phase A.

The launch of the selected satellite is scheduled for 2027.