Withstanding deep space‑like conditions marks another major milestone for PLATO, as the planet‑hunting spacecraft advances through its final pre‑launch verification steps. With this accomplishment, the spacecraft is on track to lift off in early 2027.

Back in February, PLATO was placed inside ESA’s Large Space Simulator (LSS), as its first encounter to prove that it can indeed endure the rigors of space. With the extensive test campaign conducted there now complete, PLATO has left the LSS. LSS is Europe’s single largest cryo‑vacuum chamber standing at 15 m high and 10 m wide, located at ESTEC, ESA’s technical heart in Noordwijk, the Netherlands.

The cylindrical chamber exposed all of PLATO’s components to the extreme thermal and vacuum conditions it will experience when it reaches its destination, 1.5 million kilometers away from Earth. To recreate these conditions, high‑performance pumping systems reduced the chamber pressure to space‑like levels (a billion times lower than standard atmospheric pressure). Then, the spacecraft’s cameras and electronics were kept at temperatures near −80 °C by circulating liquid-nitrogen around the simulator. The Sun‑facing surfaces were exposed to the other thermal extremes, reaching temperatures around +150 °C using an array of powerful xenon lamps simulating sunlight unfiltered by Earth’s atmosphere.

 

Pushing the hot and cold limits

Engineers also tested the entire spacecraft in so‑called hot and cold phases that pushed PLATO even beyond the conditions it will normally experience in space.

During the hot phase, all spacecraft subsystems were operated at full power, while the illuminated side was driven to maximum temperatures, carefully ensuring that the camera units still remained within their narrow operational temperature range between -70 and -90 °C.

In the cold phase, the overall temperature was reduced and PLATO’s internal heaters were used to prevent the cameras from becoming too cold. Various test sequences were performed to verify the functioning and stability of the 26 ultrasensitive cameras and the supporting systems, and to confirm that the camera performance can be maintained in flight.

Exposing PLATO to such harsh conditions seems excessive, but it is crucial to ensure it can still deliver reliable results despite temperature fluctuations.

 

What still awaits PLATO before launch?

PLATO has now exited the LSS and will proceed with the remaining final‑assembly and pre‑launch activities. These steps include concluding functional checks and preparations for shipment to the launch site later this year.

With less than a year remaining, the countdown to launch is underway. This milestone brings PLATO closer to its mission of surveying bright stars for terrestrial planets in the habitable zones of Sun‑like stars. 

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The PLATO mission’s international scientific consortium is led by Prof. Dr. Heike Rauer, planetary scientist at the Institute of Geological Sciences at the Freie Universität Berlin and the German Aerospace Center (DLR). Contributions to the mission are supported by scientists from the Freie Universität Berlin.

The contributions by Freie Universität Berlin to the PLATO mission are supported by German Federal Government via the German Space Agency at DLR (Grants 50OO1401, 50OP2103 and 50OP2104).

Plato's scientific instrumentation, consisting of the cameras and electronic units, is provided through a collaboration between ESA and the Plato Mission Consortium composed of various European research centres, institutes and industries. The spacecraft is being built and assembled by the industrial Plato Core Team led by OHB together with Thales Alenia Space and Beyond Gravity.