Milestone achieved for planet hunting mission

artist’s impression of Plato
artist’s impression of Plato
The European Space Agency’s Plato satellite, which will search for Earth-like planets orbiting the habitable zone of stars, is a step closer to launch after a UCL-led team delivered key electronics for the mission.

The Planetary Transits and Oscillations of stars (Plato) mission, due for launch in late 2026, will monitor thousands of relatively bright stars over a large area of the sky, searching for tiny, regular dips in brightness as their planets transit in front of them, temporarily blocking out a small fraction of the starlight. The analysis of these transits and of the variations in the starlight will enable astronomers to characterise the properties of the planets and their host stars.

The satellite will do this using a suite of 26 small telescopes and cameras. The read-out electronics for these cameras - the electronics that read the content of more than 80 million pixels in four seconds for each camera - have now been delivered to the Centre Spatial de Liege (Liege space centre) in Belgium, having been designed, built and tested by researchers at UCL’s Mullard Space Science Laboratory (MSSL).

Once delivered, the units are integrated with the flight optics to form cameras and further tests are performed before the assemblies are then added to the Plato spacecraft in Germany.

Astronomers have so far found over 5,000 planets beyond our solar system which are called exoplanets, but none, as yet, has been shown to be truly Earth-like in terms of its size and distance from a Sun similar to our own.

Plato will search for planets in the ’habitable zone’ of their star - the distance from the star where liquid water could exist at the surface.

Professor Alan Smith (Mullard Space Science Laboratory at UCL), Co-Investigator of the Plato mission, said: "Plato will be a ground-breaking mission with a capability beyond any that has gone before. By targeting relatively bright stars and working with our ground-based observers, we will make a huge contribution to our understanding of planetary evolution.

While some work remains in the processing of the vast dataset we have accumulated, our delivery of the read-out electronics is a major achievement and I’m very pleased to thank the dedicated team of individuals here at MSSL who have made it happen over the last 10 years." 

The MSSL team worked with partners including UK companies Teledyne Ltd, which manufactured the CCDs (charge coupled devices that convert photons into electrons), and Spur Electron Ltd, which assembled 13 of the electronics boards according to MSSL’s design.

The team at MSSL also performed a detailed calibration of each sensor (the electronics and CCDs) using vacuum chambers at MSSL that mimic the environment of space.

After launch, Plato will travel to Lagrange point 2 in space, 1.5 million km beyond Earth in the direction away from the Sun. From this point the telescope will observe more than 200,000 stars during its four-year nominal mission. 

  • Top: Artist’s impression of ESA’s Plato (PLAnetary Transits and Oscillations of stars) mission, the third medium-class mission in ESA’s Cosmic Vision programme. Plato will use 26 cameras at once to observe terrestrial planets in orbits up to the habitable zone of bright Sun-like stars, and to characterise these stars. Credit: ESA/ATG medialab
  • Middle: The sensors (electronics, CCDs and focal planes) that have been delivered by a UCL-led team. There are 24 in the picture. Two spares were also delivered. These units are for Plato’s 24 "normal" cameras that will acquire images every 25 seconds. Two "fast" cameras will also take images every 2.5 seconds.
  • Bottom: The electronics being tested in a vacuum chamber at UCL’s Mullard Space Science Laboratory (MSSL).
  • Mark Greaves

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