The work to give Plato its sensitive 26 eyes is nearing completion at OHB in Germany. 24 cameras are now installed on the spacecraft’s optical bench, the structure that keeps all cameras firmly pointed in the right direction. Two more ‘fast’ cameras will be installed in the coming weeks.

Plato will use all its cameras simultaneously to stare at the sky and discover exoplanets that orbit stars similar to our Sun, searching for potentially habitable worlds.

“It’s rewarding to see the progress we have made from last year when the work to mount the cameras started: with 24 cameras now in place, we see Plato taking its proper shape,” comments Thomas Walloschek, ESA’s Plato Project Manager.

“This activity is one of the most critical in building the satellite. The cameras are delicate elements that must be attached to the spacecraft’s supporting structure with great accuracy, to ensure that they are very precisely aligned.”

The advanced cameras are designed to capture the tiniest variations in the intensity of a star’s light. When planets pass in front of their host stars, they dim the starlight we receive. By capturing and analysing this dimming effect, Plato will spot new exoplanets.

The mission will also fundamentally advance our understanding of stars. Stars are not solid but shake like jelly. By monitoring these ‘starquakes’, encoded in subtle changes of a star’s brightness, Plato will teach us about its internal workings and age. Following-up Plato’s observations of host stars with ground-based telescopes, scientists will measure exoplanets’ sizes and masses.

Plato’s eyes have a very wide view and are specially positioned. The 24 ‘normal’ cameras are arranged in four groups of six perfectly aligned elements. The four groups look at the sky in slightly offset directions and in combination Plato’s cameras can observe about 5% of the sky at once. Over the lifespan of its survey, the mission will inspect more than 200 000 stars.

The two fast cameras image parts of the same field as the other cameras. They take images extra fast to monitor the brightest stars, and send coordinates to the spacecraft system that controls where Plato must point.

In parallel to the work on the optical bench, engineers at OHB are putting together Plato’s service module. This part of the spacecraft contains computers to operate the cameras’ electronics and other critical spacecraft components, including subsystems to control its orientation and orbital motion, propel it through space, distribute power, communicate with Earth, and handle data transfer.

The next crucial step in the construction of Plato will be joining the service module with the payload module carrying the cameras. This activity is planned to take place at OHB during the summer.