The PLATO camera

Abstract

Abstract-PLATO (PLAnetary Transits and Oscillation of stars) is a candidate for the M3 Medium-size mission of the ESA Cosmic Vision programme (2015-2025 period). It is aimed atEarth-size and Earth-mass planet detection in the habitable zone of bright stars and their characterisation using the transit method and the asterosismology of their host star. That means observing more than 100 000 stars brighter than magnitude 11, and more than 1 000 000 brighter than magnitude 13, with a long continuous observing time for 20 % of them (2 to 3 years). This yields a need for an unusually long term signal stability. For the brighter stars, the noise requirement is less than 34 ppm.hr -1/2 , from a frequency of 40 mHz down to 20 μHz, including all sources of noise like for instance the motion of the star images on the detectors and frequency beatings.Those extremely tight requirements result in a payload consisting of 32 synchronised, high aperture, wide field of view cameras thermally regulated down to -80 °C, whose data are combined to increase the signal to noise performances. They are split into 4 different subsets pointing at 4 directions to widen the total field of view; stars in the centre of that field of view are observed by all 32 cameras. 2 extra cameras are used with color filters and provide pointing measurement to the spacecraft Attitude and Orbit Control System (AOCS) loop. The satellite is orbiting the Sun at the L2 Lagrange point. This paper presents the optical, electronic and electrical, thermal and mechanical designs devised to achieve those requirements, and the results from breadboards developed for the optics, the focal plane, the power supply and video electronics.

Automatized alignment of the focal plane assemblies on the PLATO cameras

“…The cameras of the PLATO mission are fully refractive systems consisting each of 7 optical elements: 6 lenses and a flat window [2,3]. Each camera has a rotationally symmetrical field of view of ±18.9°.…”

Alignment and integration of the first PLATO camera

“…The Telescope Optical Unit (TOU) bears the optical elements; 9 the Focal Plane Array 10 11 (FPA) bears the four 4510 × 4510 pixels CCD detectors and the Front End Electronics (FEE) contains the readout electronics. 12 The payload is composed of 4 groups of 6 cameras pointing at the same portion of the sky. All groups are pointing in different directions, 9.2 degrees away from the two remaining cameras, the so-called Fast Cameras, operated at a cadence of 2.5 sec (vs 25 sec for the others), and used as Fine Guiding System.…”