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LYRA Instrument and Data Manager Software Requirements Analysis Spacebel, 5/04/05 Page 1 Agenda • • • • • Concept description LIM requirements presentation (SBI) LDM requirements presentation (SBI) Interface issues Open questions Spacebel, 5/04/05 Page 2 Concept description PROBA 2 orbit • Sun synchronous • LTAN: 6:00 • See emails F.Teston for details eclipse duration 14/04/03 0:00 26/09/02 0:00 10/03/02 0:00 time [s] •Eclipses: • approximately 3 months eclipse season • rest of the year: no eclipses • maximum eclipse duration approx. 1100 sec. 22/08/01 0:00 03/02/01 0:00 18/07/00 0:00 00/01/00 0:00 10/10/06 0:00 28/04/07 0:00 14/11/07 0:00 01/06/08 0:00 18/12/08 0:00 06/07/09 0:00 date Spacebel, 5/04/05 Page 3 Concept description PROBA 2 Pointing 1. Frames definitions Sun frame (Xsun, Ysun, Zsun) Xsun is spacecraft-sun axis ( = unit(Rsun – Rsc) where Rsun is the apparent sun vector from the Earth (Sun ephemeris) and Rsc is the spacecraft position vector. If S/C position is unknown onboard, Rsc is set to zero. Ysun is perpendicular to Xsun, in the plane defined by Xsun and the normal to the ecliptic plane, pointing towards the northern hemisphere. Ysun Xsun Rsc Sun Earth Rsun Spacebel, 5/04/05 Page 4 Concept description S/C Fixed Body Frame Mechanical frame (Xmech, Ymech, Zmech)... With respect to S/C Payload frame (Xpl, Ypl, Zpl)...With respect to SWAP Spacecraft fixed body frame (Xbof, Ybof, Zbof) ... Related to Payload frame, but origin in S/C COG. Reference frame for spacecraft attitude control. Spacebel, 5/04/05 Page 5 Concept description left B A PROBA 2 Pointing C left left left 2. Pointing in observation mode Illuminated face of the Earth D four (baseline, up to 8 possible) large-angle rotations of 90° (or 360° / number of rotations) attitudes are commanded over one orbit in order to avoid blinding of the star trackers; For the rest of presentation: baseline number of rotations assumed) the timing of the manoeuvres is such that the exclusion angles from the star trackers towards the earth are maximised; (performed on board -> cont. variation) the 90° manoeuvres will take a few minutes and will be centred around these optimal switching times; the time until the next rotation is continuously provided; paving rotations are defined in the original sun frame. Spacebel, 5/04/05 Page 6 Concept description PROBA 2 Pointing 2. Pointing in observation mode SUN Large-angle rotation around XSUN SUN* Paving rotation around YSUN and ZSUN REF The observation mode is commanded as follows: • the large rotation is commanded as a quaternion in the SUN frame: [q1cmd, 0, 0, q4cmd]; • the commanded large angle rotations will be taken from a list (of maximum 8) quaternions, configured by the ground; • the index of the currently used large angle rotation will continuously be provided; • the paving rotation is commanded as a quaternion in the SUN frame: [0, q2paving, q3 paving, q4 paving] Spacebel, 5/04/05 Page 7 Concept description • LIM mode diagram Off FDIR/TC FDIR/TC TC Warmup TC/auto Acquisition TC/auto TC/auto FDIR Idle Spacebel, 5/04/05 Page 8 Concept description • Mode simplification: – – – – Off (CSL/ROB survival mode -> idem SWAP) Idle (CSL/ROB night mode -> idem SWAP) Warm-up (CSL/ROB stand-by mode -> idem SWAP) Acquisition (CSL/ROB nominal modes) • Modes not implemented in SWIM: – First swtich on: will be performed by uploaded procedure – Bake-out mode: uploaded or onboard procedure – Calibration mode: uploaded or onboard procedure, using manually the imaging mode with different pointing configurations Spacebel, 5/04/05 Page 9 Concept description • Sequence diagram Nominal observation AOCS manager operator Payload manager Data manager IIU LYRA Set observation mode Configure pointing table Configure instrument Configure data manager Activate warm-up mode Close lumps initialisation Define & enable mode monitoring Check VFC2 Check VFC1 Switch on LOB Open cover Read times to next eclipse entry&exit Wait for sun visibility period Activate acquisition mode Set AOCS in fixed off pointing Spacebel, 5/04/05 Page 10 Switch on LOB Concept description Open cover Read times to next eclipse entry&exit AOCS Payload Data manager manager manager Wait for sun visibility period IIU LYRA Activate acquisition mode Set observation mode Set AOCS Configure pointing table in fixed off pointing Configure instrument Wait TBD sec (off pointing movement duration) Configure data manager Reload ASIC Activate warm-up mode Send acquisition Cadence Close lumps initialisation Define & enable mode monitoring Check VFC2 Check VFC1to VFC Apply 0V/2.5V/5V Switch on LOB Open cover Switch ON/OFF LED Read times to next eclipse entry&exit Repeat every LED-Pulse_Period seconds Repeat every VFC_CAL Period seconds Send data Repeat until end of sun-visibility period (eclipse duration > minimum duration of idle) Wait for sun visibility period Activate acquisition mode Read times to next Set AOCS in entry&exit fixed off pointing eclipse Calculate duration of idle time Wait TBD sec (off pointing movement duration) Reload ASIC Activate idle mode Send acquisition Cadence Close lumps Spacebel, 5/04/05 Page 11 LED-Pulse_Period seconds Send data sun-visibilit (eclipse du minimum dura Concept description Read times to next eclipse entry&exit AOCS manager operator Calculate duration of idle time Payload Data manager manager IIU LYRA Activate idle mode Set observation mode Close lumps Configure pointing table Power off CD heaters Configure instrument Power off all heads Configure data manager Activate warm-up mode Switch off all LEDS Power VFC’s Off Close lumps Close Covers initialisation Read current time Define & enable mode monitoring Check VFC2 Activate warm up mode, TBD seconds before end of Idle mode Check VFC1 Switch on LOB Open cover Read times to next eclipse entry&exit Wait for sun visibility period Activate acquisition mode Set AOCS in fixed off pointing Wait TBD sec (off pointing movement duration) Reload ASIC Spacebel, 5/04/05 Page 12 Concept description Spacebel, 5/04/05 Page 13 •Open questions Spacebel, 5/04/05 Page 14 • Interace issues Spacebel, 5/04/05 Page 15