This article originally appeared in the June 4, 2018 issue of SpaceNews magazine.

German satellite manufacturer OHB System expects to finalize a contract in June with the European Space Agency to build a spacecraft to search for exoplanets.

The contract, with an estimated value of about 300 million euros ($350 million), covers the construction of the Planetary Transits and Oscillations of stars, or PLATO, spacecraft. It is the third medium-class mission in ESA’s Cosmic Vision space science program, with an overall budget of 500 million euros.

PLATO, scheduled for launch in 2026, is intended to detect and investigate exoplanets, building upon a series of earlier missions by both Europe and NASA. PLATO aims to establish whether our solar system is unique and identify the specific characteristics of Earth-like planets in the habitable zone of stars.

“PLATO will indirectly be seeking answers to the age-old question as to whether life might exist in other solar systems,” said Andreas Winkler, head of exploration, science and human spaceflight at OHB System. “PLATO is also intended to study seismic activity of stars. Scientists will use these data to characterize more precisely the star in question and to determine its age.”

Once PLATO has reached its destination orbit around the Earth-sun L2 Lagrange point, 1.5 million kilometers away, its optical payload will detect very small and regular dips in brightness of stars that occur when planets pass in front of, or transit, stars and briefly block a small fraction of their light. The approach is similar to that used by NASA’s Kepler spacecraft and the Transiting Exoplanet Survey Satellite, launched by NASA in April.

Mission consortium

The OHB System contract with ESA covers the development and delivery of the spacecraft for the mission, including the necessary pre-launch testing and support by OHB staff during the launch campaign and the start-up phase once in space. The contract runs through the completion of in-space verification to confirm the satellite’s full performance capabilities.

As in most other ESA science missions, the complex scientific payload will be developed in parallel to the spacecraft and supplied to OHB by the PLATO Mission Consortium. That consortium includes several European research centers and institutes led by the Institute for Planetary Research (PF) in Berlin, part of the German Aerospace Center (DLR).

The payload features 26 optical cameras working in parallel at visible wavelengths, complemented by several electronic units that perform on board pre-processing of the science data.

OHB also has a role in the instrument’s development. “DLR PF has already selected OHB System for payload management support. So OHB involvement in PLATO covers both the spacecraft and the payload,” said Winkler.

Project schedule

As the prime contractor, OHB is in charge of all system-level tasks, including the overall design, development and qualification of the spacecraft, as well as of the payload module. This work will be carried out by at the OHB Optics & Science Space Center in Oberpfaffenhofen near Munich, in a special ISO Class 5 clean room.

In addition, OHB will collaborate with an existing industrial core team, including Thales Alenia Space (France and UK) and RUAG Space Switzerland, to design and develop the satellite. Thales Alenia Space, France is responsible for avionics as well as satellite positioning and orbit control, while Thales Alenia Space, UK will integrate and test the satellite platform. RUAG Space will design and assemble the optical bench used by the 26 on-board cameras, which require very precise and ultra-stable relative alignments. In addition, all cameras and support units will be delivered by the PMC.

According to Winkler, the total value of the OHB contract is around 297 million euros, with the completion of negotiations between ESA and OHB and contract signing expected for mid-June. Although coy about the exact details, Winkler adds that a “significant part” of the budget will be subcontracted by OHB to companies in Europe, including several small and medium-sized enterprises. Some of these subcontractors have already been identified, he said, with the remainder due to be selected “in the early program phases, by means of competitive tenders.”

Development of PLATO will take place in two phases. Phase 1, which lasts three years, is focused on the development of the most critical elements, as well as risk reduction and the demonstration of the main spacecraft performance. Phase 2 lasts four and half years and comprises the complete development and qualification of the spacecraft.

“We plan to achieve this in early 2026, when the spacecraft will be shipped to the launch base,” he adds. ESA plans to launch PLATO on a Soyuz rocket from Kourou, French Guiana.