ESA starts development of its Plato mission to hunt exoplanets around sun-like stars

The European Space Agency (ESA) on Wednesday, June 1, revealed that its Plato mission has entered the development stage and recently underwent testing at Europe’s largest thermal vacuum chamber. According to the agency, this test was carried out on Plato's test version of the payload module to evaluate its endurance in harsh outer space conditions. Planned for launch no earlier than late 2026, the mission is dedicated to observing 2,00,000 sun-like stars to hunt exoplanets orbiting them. 

More about ESA's Plato mission

The mission name stands for PLAnetary Transits and Oscillations of stars (Plato) and involves a telescope equipped with 26 high-resolution cameras. ESA revealed that this telescope, once launched later this decade, will be installed at the second Lagrangian point which is 15 lakh kilometres from Earth. 

The second Lagrange point, also called L2, was discovered by Joseph Louis Lagrange and is defined as a location where gravitational forces and the orbital motion of a body balance each other. This characteristic allows a spacecraft to hover and places it directly 'behind' the Earth as viewed from the Sun. It is the same location where the James Webb Space Telescope was sent last December. 

Meanwhile, the Plato telescope is being designed to look for dips in star lights caused by the transit of a planet crossing the face of its host star. In the next step, scientists would precisely determine the properties of exoplanets and the stars they orbit, investigate seismic activity in host stars of the exoplanets, characterise them and determine their age. 

What was the recent test about?

(Plato's test version of the payload module; Image: ESA)

Since the Plato spacecraft's cameras will be its most important asset, it underwent a prolonged vacuum soak to ensure that its cameras maintain a fixed optical-quality rigidity, despite the extreme conditions of deep space. The European agency tested what it calls the 'structural and thermal model' of Plato’s optical bench which is designed specifically for testing in space-like conditions. "Testing includes ‘thermal cycling’ to assess how the optical bench responds to the in-orbit temperature variations, and ‘thermal balance’ to measure the operating temperature that it maintains in these conditions", ESA said in a statement.

The testing was carried out inside the Large Space Simulator (LSS), which is said to be the largest thermal vacuum chamber in Europe. Its dimensions are 15 metres high by 10 metres wide and the facility is big enough to encompass an upturned London double-decker bus.