GERB Operations: Status Report J. Rufus GIST 26 Coseners House, RAL. 3 rd May 2007 © Imperial College London

GERB Operation Status Report GERB2 Ops Summary

GERB Operation Status Report GERB2 Mode Statistics Compare the operation of GERB2 by time in the intervals between the last three GISTs MODE 18/10/06 – 23/04/07 16/12/05 – 17/10/06 Data gathering* Autonomous Safety Packet Corruption/OFF CAL/PSF/Patch testing * Includes nightly SUNBLOCK during Sun avoidance seasons

GERB Operation Status Report GERB1 Ops Summary

GERB Operation Status Report GERB Packet Corruption Problem first appeared on GERB2-MSG1 on 21 st March Packet checksum ≠ 0 but has values which are powers of two or sums of two powers of two suggesting one or two bits in the packet are being set incorrectly. This incident was coincidentally resolved by SEU on MSG1 on the 28 th March which caused GERB2 power to be cycled. Problem began on GERB1 on 9 th October 2006 and remained until 31 st October. GERB1 in SAFE for SAS. Performed incremental shutdown the instrument in an attempt to isolate the source of the corruption.

GERB Operation Status Report Clearing Packet Corruption EUMETSAT tested the ground systems GGSPS, IMPF, IDRS and PGS and eliminated all as the source. The satellite systems were tested in order: 1.Disable the GERB packet generation and interface 2.As 1 plus reset the GERB data FIFO 3.As 2 plus disable and Enable DHSS GERB packet transmission (isolates DHSS) 4.Switch GERB to ROM mode, reboot processor and return to SAFE mode 5.Switch GERB off and return to SAFE mode Only the final step succesfully cleared the corrupt bits. Step 4 caused a ROM_WD in the transition up to SAFE. This has been attributed to the link to the AutoSUNBLOCK patch as on GERB2. With the link removed the mode changes were completed.

GERB Operation Status Report GERB2 Patch 14 – New QFM Interrupt QFM status sensors not radiation hard, subject to bit flips. The current QFM interrupt routine will move the filter until the target position is achieved. If the bit in question has been set erroneously the QFM does not move. New patch doesn’t assume QF status bits are correct, deasserts bits as the filter passes the set positions if they have been spuriously set. This may lead to rotations >360°, the first time the filter passes its target position its status is cleared, the next it is set. The patch was loaded on GERB2 on 29 th Jan and successfully tested against patch 8. Two unexpected outcomes –GERB2 post SAFE problem Upsets mirror performance

GERB Operation Status Report GERB2 Coarse flags in NORMAL post SAFE mode Coarse flag set after GERB2 leaves WAIT_LOCK mode. Software timing issue?

GERB Operation Status Report GERB2 SUNBLOCK->NORMAL post SAFE Date in SAFESUNBLOCK->NORMALWAIT_LOCK?Activity 13 Feb 2007Same dayPrep Spring SAS 12 FebSame dayFAIL x2Patch testing 29 JanSame dayLoad Patch 14 7 Nov 2006Same dayFAILClear corruption (II) 6 NovSame dayFAILClear corruption (I) 5 Oct10 OctPost Spacecraft SEU 18 AugSame dayPrep Autumn SAS 16 AugSame dayEEPROM update 9 JunSame dayFAILPSF Full Disk 7 JunSame dayPSF Full Disk 18 MaySame daySpacecraft SEU 28 AprSame dayFAILPost SAS 24 AprSame dayPatch load 2 MarSame dayROM_WD 17 FebSame dayEEPROM update 13 FebSame dayPrep Spring SAS 20 Dec 2005Same dayPatch testing 19 DecSame dayFAILPatch testing 18 Aug29 th OctSAFE for Autumn SAS 5 JulSame dayChange mirror limits

GERB Operation Status Report Clearing Packet Corruption on GERB2 during SAS Packet corruption observed on GERB2 at ~10:30pm 27 th Mar. Corruption clearing requires power cycling on instrument. First NORMAL transition post SAFE instrument at risk of detector damage if WAIT_LOCK fails. Inside the SAS season it was decided that: Allow 3 days after reset for mirror to run in. Use similar mode to that of GERB1 PSF/FORCING mode to protect detector. Corruption successfully cleared on 30 th Mar, GERB2 returned to NORMAL 3 rd Apr. FORCING mode scan table still loaded to PSF/CAL4 in GERB2 RAM.

GERB Operation Status Report GERB2 Mirror Performance versus GERB2 2006

GERB Operation Status Report GERB2 Mirror Performance versus GERB2 2006

GERB Operation Status Report GERB2 Mirror ‘Sticking’ Date# Packets 24 th Apr5, 2 12 th Feb3 31 st Jan20, 14, 3 30 th Jan9, th Jan94, 6 5 th Jan44 4 th Jan3 26 th Dec2 17 th Dec90 16 th Dec7 12 th Dec16 6 th Nov3 Mirror sticking consist of consecutive packets OOL on mirror position error GVMPERR_E and coarse flag raised. Many occurrences in Dec ’06, Jan ’07.

GERB Operation Status Report GERB2 Pre Spring SAS TL Tests Tests performed for TLs 3 to 5. Evidence of bearing deterioration. Noise associated with the useful TLs approximately doubles.

GERB Operation Status Report GERB1 Mirror Performance

GERB Operation Status Report GERB1 Preparation Pre Autumn 2007 Load New QF Interrupt Patch (15) and increase GERB1 maximum QFM rotation SW parameter (200  400 steps) Test QFM Interrupt patch versus AutoSUNBLOCK patch (12) Load and test FORCING mode (CAL10?) Slight change to previous tests scan table due to patch 15. Update GOP and EUMETSAT procedures to reflect new mode, mirror mispointing behaviour, new interrupt (remove additional QFM rotations to ensure status is defined) Update instrument EEPROM with new patches when successfully tested. Remove links to patch 12 in EEPROM to avoid ROM_WD. Produce SOIs for GERB1 to prepare the instrument for SA season, shutdowns in and out of the seasons. Run TL test (2-4?) Extend beyond 1hr in each TL? Multiple tests? Revisit mirror safety settings?

GERB Operation Status Report Future Ops GERB2 After MSG1 becomes mission backup on May 10 th GERB2 will be left in SAFE mode SEVERI on MSG1 will operate in two modes post 10 th May 26 days rapid scan plus two days standard (x11) 28 days standard scan (x1) GERB2 should be run at least every six months to cross calibrate and check instrument performance Because of difficulties over first transition to NORMAL mode and mirror upsets it is not anticipated that GERB2 will be gather data during either SAS 4 out of 6 SW calibration dates available 9 th Feb, 29 th Apr, 11 th Aug, 3 rd Nov.[21 st Mar, 21 st Sep] Suggestion from GIST as to best times to run

GERB Operation Status Report GERB1 Mirror Mispointing Tests Mirror mispointing errors noted during commissioning associated with invalid mirror demand values after mode transitions. They spontaneously resolved after a large mirror spike after seemingly random times. Tests observed transitions between different modes (24 th Apr) and narrowed problem to mode changes between non-rotating and rotating mirror states. In practical terms SAFE→SUNBLOCK, NORMAL, CALx Prompt correction in scanning modes, random in SUNBLOCK (20’+) Presents problems operating GERB1 in Sun Avoidance when large correction risks Solar exposure. Wait for long periods in SUNBLOCK. Identify Correction? Wastes time. Do not use SAFE during SA. Find a safe way to force correction.

GERB Operation Status Report GERB1 Mirror Mispointing Tests Use rapid correction of scanning modes and safety of SUNBLOCK to define new forcing mode. Mirror performs scans of the Earthview as NORMAL but the filter position is left blocked for the duration of the scan. Test mode by SAFE↔FORCING ten times and observing SOEP. Test successful in all instances within a GL0, 2’30”. More testing required?

GERB Operation Status Report Overview One month of dual operations [Jan/Feb] Currently running dual ops [19 th Apr – 10 th May] Collected data through SAS Run a number of dual calibration ops [SW cals, lunar obs] Loaded and tested new QFM interrupt patch Some data loss on GERB2 through SAS because of safety transitions and packet corruption Deterioration in GERB2 mirror performance Post SAFE problem on GERB2 also Future ops planning

GERB Operation Status Report GERB2 Mirror Performance

GERB Operation Status Report GERB2 Mirror Rough Running Jan 2007 Feb Mar Bearing noise illustrated by the velocity range telemetry. Large spike indicate mode changes, serious mirror disturbances. General trend in January is flat but rises sharply after the mirror is stopped for the patch load on the 29 th. After that the mirror runs consistently noisier.

GERB Operation Status Report GERB2 Mirror Daily Checks