Schematic figure of one of the cameras of the PLATO spacecraft. Credit: PLATO Mission Consortium

The key scientific requirement to detect and characterise a large number of terrestrial planets around bright stars determined the design of PLATO's payload module. The module provides a wide field-of-view (FoV) to maximise the number of the sparsely distributed bright stars in the sky with one pointing, and allows the satellite to cover a large part of the sky. In addition, it provides the required photometric accuracy to detect Earth-sized planets and a high photometric dynamic range, allowing astronomers to observe bright stars (m_V < 11) as well as fainter stars down to V-magnitude of 16. This performance is achieved by a multi-telescope instrument concept, which is novel for a space telescope.

The payload consists of 24 'normal' cameras with CCD-based focal planes, operating in white light. They will be read out with a cadence of 25 s and will monitor stars with m_V > 8. Two additional 'fast' cameras with high read-out cadence (2.5 s) will be used for stars with m_V ~4–8.  The 'normal' cameras are arranged in four groups of six. Each group has the same field-of-view but is offset by a 9.2° angle from the payload module +Z axis, allowing astronomers to survey a total field of about 2250 deg² per pointing, but with different sensitivities over the field.

The ensemble of instruments is mounted on an optical bench. The cameras are based on a fully dioptric design with 6 lenses. Each camera has an 1100 deg² field-of-view and a pupil diameter of 120 mm and is equipped with a focal plane array of 4 CCDs each with 4510×4510 pixels of 18 μm size, working in full frame mode for the 'normal' camera and in frame transfer mode for the 'fast' cameras.

Payload Consortium contributions