GE+ PL INTERFACES, RESSOURCES PLATO PPLC/ESA meeting, Feb 27th 2009

GE + PL Unobstructed field of view instrument needs a UFOV defined as a cone, centred on the Z axis of the instrument, half angle of 30° (without margin) Sun shield the Sun shield is the first stage of the baffling system the line of the Sun shield shall be carefully treated to reduce the diffused light in direction of the telescope individual baffles protects an angle of 30° in heigth (as in the CDF design) PLATO Optics I/F PPLC/ESA meeting, Feb 27th 2009

PLATO Electronics architecture GE + PL PPLC/ESA meeting, Feb 27th 2009 Homogeneous with 40 telescopes in 4 groups Failure tolerant architecture Fully redundant on ICU

GE + PL On Bord Time and synchronisation High frequency clock line and Time Marks to synchronise all activities in the instrument with the SVM, signals provided by SVM Pointing error for the AOCS Dedicated lines (1 M + 1 R), Frequency: 1 set of data every 2.5 sec, Delay from middle of exposure time to delivery : typically 1.6 s, (TBC) Data format, units, precisions… TBD Data lines 2 spacewire links (1M + 1R), PLATO Electrical I/F (1) PPLC/ESA meeting, Feb 27th 2009

GE + PL Power lines… 12 regulated primary power lines, (8 MEU, 2 ICU, 2 fastDPU) Housekeeping lines ~0 (TBC) analog lines coming from telescopes or electronics boxes Thermal control lines ~400 (TBC) temperature sensor lines 42 thermal lines (heaters and sensors) for the active control of each telescope 4 (TBC with the number of radiators) thermal lines (heaters and sensors) for the active control of the thermal plate supporting the electronics boxes PLATO Electrical I/F (2) PPLC/ESA meeting, Feb 27th 2009

GE + PL Telescope I/F with the other parts of the instrument Environment of the telescopes mean temperature of the inner walls of the Sun shield, radiative characteristics of it or its coating or covering, in the different mission phases variations of temperature Optical Bench mean temperature during all phases Thermal plate 564 W are dissipated by the electronics boxes on this plate, at a temperature range of [-40, +40°C] measured at the PRT of the boxes  radiator size temperature when electronics are OFF shall stay in the storage temperature range of the electronics boxes  power needed for that possibility of radiative and conductive exchange with SVM ?? PLATO Thermal I/F PPLC/ESA meeting, Feb 27th 2009

GE + PL SystemSub-systemUnit mass (kg) Number of units Total (without margin) Remarks Telescope Glass7.5 Structure+mounting5.0 Baffle0.8 Thermal equipment0.5 FPA0.8 FEE MEU (5 DPU) Harness20.01 Fast FEE ICU (box of 2)4.01 Total737.6 ~505 kg in the CDF design PPLC/ESA meeting, Feb 27th 2009 PLATO Mass budget

GE + PL Status: all lines shall be consolidated ; only glass mass, baffle mass, FPA mass are better known the electronics boxes mass are evaluated with wall thickness of 3.0 mm in aluminium, but shall be consolidated How to reduce the mass budget ? seems difficult on our side (telescopes + electronics) the only way could be a reduction of the number of telescopes (important science impact) the other parts of the instrument could be re-visited :  heigth of the Sun shield is lower as in the CDF design (overall size of the telescopes has been reduced)  OB could evolve to a trellis of bars (mass saving ?) Better optimization of the SVM for the instrument PLATO Mass budget PPLC/ESA meeting, Feb 27th 2009

GE + PL Per unitNumber of units Total (without margins) Remarks Telescope thermal FEE (incl.FPA) MEU (5 DPU) ICU (box of 2)9.41 Fast FEE (DPU) Totals709 W ~250 W in the CDF design PPLC/ESA meeting, Feb 27th 2009 PLATO Power budget

GE + PL Status: effect on focus of 2.5 W shall be evaluated with thermal analysis and optics sensitivity power values for electronics are evaluated with DC-DC converters efficiency of 0.7 (conservative, some margin) high speed ADC consumption could evolve with new technology developments in the next years (0.5 W on an ADC corresponds to ~60 W in the budget) How to reduce the power consumption ? Increase the exposure time for normal telescopes to 50 s (instead of 25 s) increase the saturation of spots, oblige to extract the photometry of saturated stars increase the confusion between spots reduce the power consumption of FEE (phase drivers, ADC…), of DPU (same number of operations in twice time) PLATO Power budget PPLC/ESA meeting, Feb 27th 2009