Detecting as many exoplanets as possible, around different types of stars, over long durations, requires:
- a wide field of view,
- a large collecting area,
- a long mission lifetime.
In order to meet the first two requirements, ESA decided to select a 32-telescope design. The telescopes are identical and grouped in 4 groups of 8. All 8 telescopes in a single group observe the same field. The groups are slightly offset from each other so that their respective fields partially overlap (as shown in the figure below). This method provides a better signal to noise ratio in certain parts of the overall field of view, especially in the centre, where 32 telescopes’ fields of views overlap. This redundancy also reduces the impact of any one telescope malfunctioning.
2 additional “fast” telescopes are in charge of the satellite’s fine pointing.
Plato’s overall field of view is 2250°².
Plato’s field of view. The 4 telescope groups’ fields of view overlap in some areas to provide a better signal to noise ratio in these areas.
The telescopes are equipped with 6 lenses and offer the following features:
- 4 CCDs with 18 µm pixels
- 4510 x 4510 pixels per CCD
- Total height: about 37 cm (without baffle)
- Mass: about 13.2 kg
- Reading rate: 25 s (2.5 s for the 2 fast cameras)
3D model of a telescope
18 computers (including 2 for the fast cameras) will process data provided by the telescopes: light curves, centroids, pictures, etc. They will then transmit it to the Instrument Control Unit (ICU) which will consolidate the data before sending it to the ground stations. The ICU will also relay ground commands.
Plato’s payload will have a mass of about 600 kg and use about 800 W of power. It will produce 103 Gb of data each day.