PLATO Payload


The PLATO  PayloAd

The PLATO instrument concept is based on a multi-telescope approach, involving a set of 32 Normal Cameras working at a cadence of 25 sec and monitoring stars fainter than mV = 8, plus 2 Fast Cameras working at a cadence of 2.5 sec, and observing stars in the magnitude range 4 to 8.

The Cameras are based on a fully dioptric telescope including 6 lenses; each Camera has an 1100 deg2 field, and a pupil diameter of 120 mm.

The 32 Normal Cameras are arranged in four groups of 8 Cameras. All 8 Cameras of each group have exactly the same field of view, and the lines of sight of the four groups are offset by a 9.2° angle from the +ZPLM axis. T
his particular configuration allows surveying a total field of about 2250 square degrees per pointing, with various parts of the field monitored by 32, 24, 16 or 8 telescopes. This strategy optimizes both the number of targets observed at a given noise level and their brightness. It is assumed that the satellite will be rotated around the mean line of sight by 90°every 3 months, resulting in a continuous survey of exactly the same region of the sky.

Each Camera is equipped with its own CCD focal plane array, comprised of 4 CCDs with 4510x4510 pixels, 18 μm pixels, working in full frame mode for the Normal telescopes, and in frame transfer mode for the Fast telescopes. A total of 132 CCDs covering an area of ~1 m2 make the PLATO focal plan. The CCD working temperature is -65°C. The focal plane is cooled down through a thermal link with the telescope, the energy being radiated away by the baffle. The power dissipated by the front-end electronics linked to each focal plane is evacuated by the optical bench (PLM).

There is one Data Processing Unit (DPU) per 2 Cameras performing the basic photometric tasks and delivering a set of light curves, centroid curves and imagettes to a central Instrument Control Unit (ICU), which stacks and compresses the data, then transmits them to the Service Module (SVM) for downlink. Data from all individual Cameras are transmitted to the ground, where final instrumental corrections, such as jitter correction, are performed. The DPUs of the fast Cameras will also deliver a pointing error signal to the AOCS, at a cadence of 2.5 sec. Several photometry algorithms (plain aperture photometry, weighted mask photometry, Line Spread Function fitting) are planned to run on board, each star being allocated one of them, depending on its brightness and level of confusion.

The PAYLOAD is managed by:

  1. Payload Management who coordinates a

  2. Camera Team

  3. Telescope Optical Units (TOUs)

  4. Focal Plane Assembly/Front End Electronics  (FPA/FEE)

  5. Prototype and FM AIV

  6. Ancillary Electronics Units (AEUs)

  7. Data Processing System Team

  8. Instrument Control Unit (ICU)

  9. Normal Digital Processing Units (N-DPUs)

  10. Fast Digital Processing Units (F-DPUs)

  11. Algorithms

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