A milestone has been reached in the search for planets beyond our solar system. The European Space Agency’s (ESA) Plato spacecraft has officially completed construction, with the final fitting of its sunshield and solar array module now in place
Engineers will now begin a crucial series of environmental tests to prepare the spacecraft for its planned launch in December 2026.
A new era for exoplanet exploration
Plato is part of ESA’s ambitious Cosmic Vision programme. Its mission is to discover Earth-like exoplanets orbiting stars similar to our Sun, including those that lie within the so-called habitable zone, where conditions might allow liquid water to exist.
To accomplish this, Plato will monitor over 150,000 bright stars at once using a powerful suite of 26 cameras. These instruments are designed to detect tiny dips in brightness as planets pass in front of their host. By studying these transits in detail, scientists hope to identify terrestrial planets with characteristics similar to Earth.
Built for precision
Now fully assembled, Plato includes two critical components: a large sunshield and an array of solar panels. The sunshield protects its sensitive cameras from the glare and heat of the Sun, keeping the instruments at a stable operating temperature of around -80°C. This stability is essential for capturing the precise measurements needed to detect faraway worlds.
The solar panels, which were successfully tested on Earth using simulated sunlight and a pulley system to mimic weightlessness, will provide the necessary power to run the spacecraft’s systems. Once in space, these panels will unfold like wings to harness energy from the Sun.
The UK’s role
The UK has played a big part in the Plato mission, contributing cutting-edge technology and scientific leadership. With £25 million invested by the UK Space Agency between 2014 and 2024, UK institutions have been involved at every stage of development.
Key contributions include camera electronics developed by UCL’s Mullard Space Science Laboratory and advanced CCD detectors manufactured by Teledyne e2v.
The University of Cambridge is leading a consortium to develop the UK’s Plato Data Centre, supported by other leading institutions such as the Universities of Birmingham, Oxford, St Andrews, and the Open University. Meanwhile, Thales Alenia Space UK contributed to avionics and service module integration, working alongside lead contractor OHB.
Testing before takeoff
Although construction is now complete, Plato still has a series of demanding tests ahead. These include vibration and acoustic trials to simulate the extreme conditions of launch, as well as cryo-vacuum testing inside Europe’s largest space simulator. These tests will expose the spacecraft to the vacuum and temperature extremes it will face in orbit.
The spacecraft’s ability to endure these harsh conditions is essential to ensure it can carry out its mission reliably for years after launch.
With final testing underway, Plato remains on schedule to launch aboard an Ariane 6 rocket in December 2026. Once in space, it will begin its long-awaited mission to expand our understanding of distant solar systems.
