HFI operations

From Planck Legacy Archive Wiki
Revision as of 10:33, 28 January 2013 by Lvibert (talk | contribs)
Jump to: navigation, search

Overview[edit]

All satellite operations including the HFI instrument ones are under ESA MOC responsibilty for obvious safety reasons.The HFI instrument operations are nevertheless delegated to the HFI Instrument Operations Team (IOT) built from the HFI consortium and under the HFI Principal Investigator responsibility. Instrument management, operations and parameter monitoring are thus prepared and controlled by the IOT and serviced by MOC either in near real time during the DTCP or uploaded in the satellite mission timeline for defered execution. The HFI instrument health and science data quality has been monitored daily by the IOT from launch till the end of the HFI extension mission phase. Apart from ground based tests, different operations phases did occur:

  • 14/05/2009-18/05/2009 Launch Early Operational Phase
  • 18/05/2009-09/07/2009 Commissioning Phase. The operations during this phase were under ESA's Planck Project responsibilty. The main HFI activities have been functional tests of the instrument and its cooldown till 100 mK. Given the performance, the helium flow has been set to the minimal one giving an End Of Life estimation second half of January 2012.
  • 10/07/2009-12/08/2009 Calibration and Performance Verification Phase. The operations during this phase were under ESA's Planck Science Office responsibilty. The main HFI operations have been performance tests and activities to mesure the effects of several systematics. The only instrument failure happened the 6th of August were the electronic part of the 4K cooler has been switched off probably due to a major cosmic particle. It has to be noted that no tuning of the HFI parameters have been executed in flight till the end of the full HFI mission, excepted in December 2009 for an adjustment of the on-board numerical compression parameters.
  • 12/08/2009-28/11/2010 HFI Nominal mission
  • 28/11/2010-13/01/2012 HFI Extended mission
  • 13/01/2012-(to be continued) LFI "only" extension phase

Timeline[edit]

The following list (version 11/09/2012) gives some known events and activities that have affected or might have affected the HFI data. The time information is the start time of the event in On Board Time. The label contains few keywords:

  • dtcp : (for Daily Tele-Communication Period) refers to extended pass
  • HFI : refers to HFI instrument operations (when during the Commissioning of the Calibration and Performance Verification phases, labels are usually followed bu the activity label)
  • period: refers to the different phases of the mission
  • test : refers to End Of Life tests executed on the HFI
  • therm : refers to satellite events that might have a thermal impact on the HFI
  • sat : refers to operations on the satellite SerVice Module that might have an impact on the HFI data
  • slew : refers to thruster activity
  • solar flare : refers to all solar events as detected by a thermal fluctuation on the HFI bolometer plate


14/05/2009 13:12:00	EPC Vulcain Engine ignition
14/05/2009 16:58:36	HFI NSFF: switch on HFI LCLs
14/05/2009 17:30:59	HFI NTSN: HFI go from startup to standby 
14/05/2009 17:36:08	HFI PFDR: choose DPU FDIR mode Desynchro
14/05/2009 17:39:39	HFI DVOP: open dilution cooler valves
14/05/2009 18:48:52	HFI ENSF: setup Ns (40Hz) and Fdiv (124) REU parameter
14/05/2009 18:52:33	HFI 4KFIT: set the 4K cooler internal frequency at 40Hz
14/05/2009 19:05:45	HFI ECXC: activation of cernox thermometers
14/05/2009 19:08:51	HFI 4SYS: synchronise the 4K cooler clock (External)
14/05/2009 19:23:47	HFI 4ADM: set the 4K cooler amplitude at 2000 microns
14/05/2009 19:28:42	HFI 4GEC: power on nominal 4K getter
14/05/2009 19:35:31	HFI 4COR: run 4K cooler
15/05/2009 12:00:00	therm: stop the Focal Plane Unit 250K heating
15/05/2009 19:17:06	slew: OCM LEOP (MAN-01a)
16/05/2009 12:06:55	HFI EBON: HFI switch on all REU analog belts
16/05/2009 12:17:23	HFI EFPR: REU FPGA reset
16/05/2009 12:26:40	HFI 4COR: run 4K cooler
16/05/2009 12:31:16	HFI CJjP: JFET controlled at 110K
16/05/2009 12:49:26	HFI PCMP: Compression control of all belts: warm FPU
16/05/2009 12:54:37	HFI ERSS: raw signal cycle on channels
16/05/2009 14:20:15	HFI science data production starts
16/05/2009 14:48:30	HFI CbcP: all 72 channels setup for warm FPU
16/05/2009 15:03:18	HFI EOPC: parameter setup for 1st optim of all bolos, all thermos and Resistor
16/05/2009 15:15:37	HFI ECLS & NCPN: select & optim for all bolos, all thermos and Resistor
16/05/2009 15:37:06	HFI EVIC: config of the VI parameters (identical for bolos, thermos & Resistor)
16/05/2009 15:39:43	HFI ECLS + NCVN: VI for all bolos, thermos & R for VI
16/05/2009 16:00:00	HFI PEOS: first of the hourly end of slew
18/05/2009 00:00:00	period: end of LEOP / start of Commisioning phase
01/06/2009 21:36:00	therm: end of reflectors anticontamination
02/06/2009 16:40:20	HFI CJjP: JFET controlled at 130K 
02/06/2009 17:00:06	HFI EHWT: test of belts
02/06/2009 17:20:06	HFI 4COR: run cooler
02/06/2009 17:29:55	HFI CA0P+CA1P+NCPN: Resistor and Capacitor optimisation with Nblanck=0
02/06/2009 17:39:56	HFI EECS: save config in REU EEPROM
03/06/2009 17:24:00	therm: SCS active cooldown starts
05/06/2009 17:28:18	slew: OCM-z (MAN-02a)
09/06/2009 16:29:33	HFI CH6P: activate 18K-4K switch (repeted every day till OD42)
09/06/2009 22:28:02	HFI Single Event Upset
12/06/2009 03:00:00	HFI QEC1: electrical check of the bolometers at 100K
12/06/2009 15:32:10	HFI CPSP: activate the 4K-1.6K heat switch at max power (N&R)
12/06/2009 15:33:31	HFI CP4P: activate the 4K PID at max power (N&R)
15/06/2009 03:00:00	HFI LFER_A_WARM test
17/06/2009 16:46:58	slew: OCM-z touch-up (MAN-02b)
18/06/2009 18:29:57	HFI LFER_A_WARM
24/06/2009 10:40:15	HFI CPSP+CP4P: switch off the 4K-1.6K heat switch and the 4K PID
24/06/2009 10:44:36	HFI CH6P: set the 18K-4K switch to control the pump temperature at 57K (LFI test): 1st attempt
24/06/2009 10:49:01	HFI 4ADM: compressor amplitude demand at 3500 microns
24/06/2009 10:52:48	HFI DFVO: open the 3 latch valves FV103, FV104 and FV202 (dilution flow FNOM2)
24/06/2009 11:18:58	HFI CH6P: set the 18K-4K switch to control the pump temperature at 57K (LFI test): 5th and last attempt
26/06/2009 23:00:00	HFI CH6P: power off the 18K-4K switch
28/06/2009 12:22:14	HFI CA0P & CA1P: 3 channel setups of the Resistor and the Capacitor for LFER test
28/06/2009 12:53:22	HFI 4K cooler amplitude tuning 1/2
29/06/2009 09:38:15	HFI 4K cooler amplitude tuning 2/2
30/06/2009 09:38:16	to be continued …
02/07/2009 11:15:46	slew: OCM Insertion (MAN-03a)
02/07/2009 13:52:08	Change of REU mode (OPTIM)
03/07/2009 11:55:57	Change of REU mode (OPTIM)
03/07/2009 12:56:43	Change of REU mode (OPTIM)
03/07/2009 22:00:02	HFI  pre-RAW72
03/07/2009 23:13:02	Change of REU mode (RAW72)
04/07/2009 02:00:00	therm: aphelion
04/07/2009 22:30:02	Change of REU mode (COMPRESSION-VALIDATION)
04/07/2009 23:05:10	Change of REU mode (COMPRESSION-VALIDATION)
04/07/2009 23:40:18	Change of REU mode (COMPRESSION-VALIDATION)
05/07/2009 00:10:20	Change of REU mode (COMPRESSION-VALIDATION)
05/07/2009 00:15:27	Change of REU mode (COMPRESSION-VALIDATION)
05/07/2009 00:45:26	Change of REU mode (COMPRESSION-VALIDATION)
05/07/2009 00:50:35	Change of REU mode (COMPRESSION-VALIDATION)
05/07/2009 01:25:43	Change of REU mode (COMPRESSION-VALIDATION)
10/07/2009 00:00:00	Start of CPV phase
12/07/2009 00:34:38	HFI Single Event Upset
12/07/2009 01:00:02	HFI  RAW72
12/07/2009 07:00:04	HFI  end of RAW72
12/07/2009 11:53:20	DPU is rebooted
15/07/2009 09:16:02	slew: OCM Insertion touch-up (MAN-03b)
27/07/2009 01:56:42	HFI Single Event Upset
31/07/2009 16:00:00	HFI SUNI_1_1
01/08/2009 00:00:00	HFI SUNI_1_2
01/08/2009 10:55:00	HFI SPIN day 1 : RPM@1.05
02/08/2009 12:20:00	HFI SPIN day 2 : RPM@0.95
03/08/2009 11:53:37	HFI SPIN day 3 : RPM@1.00
03/08/2009 11:53:37	HFI SPIN day 4 : RPM@1.00
05/08/2009 09:36:01	slew: 1.7' slews test
05/08/2009 10:36:27	HFI save REU then DPU final configuration     
06/08/2009 10:00:00	HFI SUNI_2_1
06/08/2009 17:31:31	4K CRU anomalous shutdown
06/08/2009 18:00:00	HFI SUNI_2_2
08/08/2009 14:05:36	period: first light survey
09/08/2009 03:58:53	star tracker switchover #1
12/08/2009 13:24:59	Change of REU mode (OPTIM)
12/08/2009 14:13:45	period: DPC survey#1 (ring#240)
14/08/2009 12:30:10	slew: orbit maintenance manoeuvre #1
18/08/2009 11:43:42	long ring #440 for CDMU patch day 1
18/08/2009 12:39:09	sat: CDMU patch (day 1)
18/08/2009 12:39:20	sat: CDMU patch (end of day 1)
19/08/2009 11:49:40	long ring #474 for CDMU patch day 2
19/08/2009 12:45:31	sat: CDMU patch (day 2)
19/08/2009 12:45:34	sat: CDMU patch (end of day 2)
20/08/2009 11:53:46	long ring #509 for CDMU patch day 3
20/08/2009 12:45:32	sat: CDMU patch (day 3)
20/08/2009 12:45:36	sat: CDMU patch (end of day 3)
21/08/2009 11:56:03	long ring #544 for CDMU patch
21/08/2009 14:18:48	HFI clock resynchronisation
22/08/2009 09:36:51	dtcp: transition to 3 h DTCP duration
31/08/2009 12:09:14	long ring #897 to allow the execution of the ACMS warm reset
31/08/2009 13:40:00	thrusters catbed heaters are switched off by error
31/08/2009 13:40:01	sat: FOG telemetry is disabled by error
31/08/2009 13:41:05	long ring #898 to allow the execution of the ACMS warm reset
04/09/2009 15:01:00	thurster under/over performed
11/09/2009 21:00:41	slew: orbit maintenance manoeuvre #2
16/09/2009 20:31:41	thrusters catbed heaters are switched back on
18/09/2009 19:06:15	planet: HFI Crab scan#1
20/09/2009 19:36:00	dtcp: extra pass CEB
20/10/2009 23:44:24	therm: HFI elephant LONG deltaT>10uK
22/10/2009 19:34:56	planet: HFI Mars scan#1
24/10/2009 11:01:39	therm: HFI elephant LONG deltaT>10uK
25/10/2009 15:30:49	planet: HFI Jupiter scan#1
28/10/2009 23:06:00	thurster under/over performed
01/11/2009 00:41:04	planet: HFI Neptune scan# 1
20/11/2009 18:52:25	long ring #3589 (29 hours) : no slew due to MTL uplink problem
21/11/2009 23:39:54	slew : resumption of SL after the MTL problem
22/11/2009 19:48:41	slew to SGR position
23/11/2009 08:47:54	slew to catchup
23/11/2009 19:48:10	SGR (end): back to nominal scanning law
25/11/2009 05:56:00	HFI 1.6K stage event
26/11/2009 14:32:00	thurster under/over performed
04/12/2009 17:49:29	slew: orbit maintenance manoeuvre #3
05/12/2009 09:43:53	planet: HFI Uranus scan# 1
16/12/2009 20:42:11	sat: FOG telemetry is enabled back
21/12/2009 19:59:54	HFI compression settings change
22/12/2009 11:46:18	dtcp: extra pass
03/01/2010 00:00:00	therm: perihelia
04/01/2010 00:25:49	planet: HFI Saturn scan#1
11/01/2010 19:16:32	star tracker switchover #2
15/01/2010 21:57:45	slew: orbit maintenance manoeuvre #4
25/01/2010 21:16:41	sat: transponder always on
08/02/2010 20:51:32	period: DPC survey#2 (ring#5721)
26/02/2010 12:43:37	star tracker switchover #3
26/02/2010 23:02:49	slew: orbit maintenance manoeuvre #5
06/03/2010 05:04:43	planet: HFI Crab scan#2
01/04/2010 06:41:00	thurster under/over performed
02/04/2010 13:48:21	therm: major elephant
05/04/2010 10:00:00	solar flare: geomagnetic storm
10/04/2010 10:36:35	planet: HFI Mars scan#2
26/04/2010 17:55:37	slew: orbit maintenance manoeuvre #6
29/04/2010 17:34:58	therm: SCS TSA setpoint increase
06/05/2010 17:02:08	therm: SCS TSA setpoint increase
13/05/2010 16:30:13	therm: SCS TSA setpoint increase
17/05/2010 17:51:09	planet: HFI Neptune scan# 2
12/06/2010 01:00:00	solar flare
12/06/2010 01:57:16	planet: HFI Saturn scan#2
24/06/2010 18:31:09	therm: SCS TSA setpoint increase
30/06/2010 19:00:53	planet: HFI Uranus scan#2
03/07/2010 20:01:43	planet: HFI Jupiter scan#2
06/07/2010 11:00:00	therm: aphelion
14/07/2010 20:45:50	dtcp: extra pass
15/07/2010 18:13:43	therm: SCS TSA setpoint increase
18/07/2010 04:28:00	thurster under/over performed
21/07/2010 21:08:44	therm: moon transit
22/07/2010 00:42:59	therm: moon transit (end)
24/07/2010 16:36:11	therm: HFI elephant LONG deltaT>10uK
29/07/2010 17:45:52	therm: SCS TSA setpoint increase
03/08/2010 19:00:00	solar flare: possible geomagnetic storm
11/08/2010 10:14:37	long ring #11149 for SCS switchover
11/08/2010 11:00:00	therm: SCS switchover
11/08/2010 21:34:10	dtcp: extra pass CEB
12/08/2010 19:27:28	period: DPC survey#3 (ring#11195)
13/08/2010 23:59:21	slew to interleaved pointings for survey#3
14/08/2010 11:00:00	solar flare
16/08/2010 18:00:09	slew: orbit maintenance manoeuvre #7
18/08/2010 08:35:00	solar flare
18/09/2010 18:28:04	planet: HFI Crab scan#3
04/10/2010 04:25:00	HFI 1.6K stage event
04/10/2010 04:57:05	therm: HFI elephant SHORT deltaT>10uK
06/10/2010 19:00:46	dtcp: extra pass CEB
11/10/2010 13:26:47	long ring  #13333: manoeuvre failed
03/11/2010 08:11:34	planet: HFI Neptune scan#3
04/11/2010 13:20:14	therm: change of the DPU2 thermal control
04/11/2010 19:19:00	dtcp: extra pass NNO
11/11/2010 12:45:00	therm: SCS TSA setpoint increase
21/11/2010 03:02:51	therm: HFI elephant LONG deltaT>10uK
24/11/2010 11:23:01	long ring  #14627 for star tracker tests
24/11/2010 12:29:29	star tracker switchover for intercalibration test (STR1->STR2)
24/11/2010 20:23:53	slew back
25/11/2010 17:02:45	long ring  #14653 for star tracker tests
25/11/2010 17:59:37	star tracker switchover STR2->STR1
26/11/2010 01:55:21	slew back to nominal scanning strategy
27/11/2010 20:20:00	solar flare
02/12/2010 13:21:13	slew: orbit maintenance manoeuvre #8
06/12/2010 20:38:00	planet: HFI Jupiter scan#3
10/12/2010 14:55:44	planet: HFI Uranus scan#3
15/12/2010 08:19:00	thurster under/over performed
15/12/2010 10:30:00	thurster under/over performed
22/12/2010 16:33:14	HFI Single Event Upset
23/12/2010 15:44:53	therm: SCS TSA setpoint increase
03/01/2011 19:00:00	therm: perihelia
18/01/2011 05:25:24	planet: HFI Saturn scan#3
24/01/2011 13:20:09	therm: SCS warm radiator warming
24/01/2011 17:28:00	dtcp: extra pass CEB
28/01/2011 02:00:00	solar flare
31/01/2011 14:06:49	slew: orbit maintenance manoeuvre #9
01/02/2011 13:31:33	therm: SCS TSA setpoint increase
08/02/2011 20:55:48	period: DPC survey#4 (ring#16692)
10/02/2011 02:48:02	HFI 1.6K stage event
15/02/2011 06:00:00	solar flare: X ray solar flare
18/02/2011 00:00:00	solar flare: X ray solar flare
24/02/2011 14:05:28	therm: SCS TSA setpoint increase
28/02/2011 23:20:41	slew: acceleration for Crab scan
06/03/2011 04:12:44	planet: HFI Crab scan#4
07/03/2011 21:00:00	solar flare: coronal mass ejection
10/03/2011 19:44:00	dtcp: extra pass CEB
15/03/2011 17:42:31	therm: SCS desorption power gap jump
15/03/2011 20:35:00	dtcp: extra pass
18/03/2011 15:15:00	dtcp: long pass (5h30mn)
21/03/2011 03:30:00	solar flare: radiation event
21/03/2011 21:10:17	slew: orbit maintenance manoeuvre #10
31/03/2011 21:02:52	therm: SCS TSA setpoint increase
07/04/2011 20:38:16	therm: SCS TSA setpoint increase
14/04/2011 21:03:33	therm: SCS TSA setpoint increase
21/04/2011 20:33:20	therm: SCS TSA setpoint increase
10/05/2011 16:48:13	therm: SCS TSA setpoint increase
20/05/2011 14:18:21	planet: HFI Neptune scan#4
04/06/2011 22:00:00	solar flare: geomagnetic storm
07/06/2011 07:00:00	solar flare: solar proton enhancement
23/06/2011 04:55:03	thurster under/over performed
29/06/2011 17:03:39	planet: HFI Saturn scan#4
04/07/2011 15:00:00	therm: aphelion
05/07/2011 22:00:17	planet: HFI Uranus scan#4
25/07/2011 17:38:00	slew: orbit maintenance manoeuvre #11
27/07/2011 16:51:00	on board mass properties update
29/07/2011 17:13:00	slew to survey#5
29/07/2011 17:43:32	period: DPC survey#5 (ring#21721)
02/08/2011 07:00:00	solar flare: M1 class
03/08/2011 21:09:40	planet: HFI Jupiter scan#4
04/08/2011 04:30:00	solar flare
04/08/2011 15:55:38	therm: SCS TSA setpoint increase
08/08/2011 16:53:00	SGR: scanning law is interrupted
08/08/2011 17:32:00	slew back
08/08/2011 18:00:00	solar flare: X7 class
08/08/2011 18:44:00	planet: HFI Jupiter scan#4 (bis)
09/08/2011 01:54:00	slew to the catchup position
09/08/2011 08:00:00	solar flare
09/08/2011 17:23:00	SGR (end): back to nominal scanning law
06/09/2011 02:20:00	solar flare: M5.3
06/09/2011 23:00:00	solar flare: X2.1
13/09/2011 09:34:22	planet: HFI Crab scan#5
17/09/2011 08:00:00	solar flare: magnetic storm
20/09/2011 09:43:00	slew setting-up the second crab scan 
20/09/2011 10:41:38	planet: HFI Crab scan#5 (bis)
21/09/2011 16:43:41	planet: HFI Crab scan#6
21/09/2011 18:33:00	dtcp: extra pass
22/09/2011 12:00:00	solar flare: complexe event
24/09/2011 00:42:34	slew back to survey 5 scanning strategy 
26/09/2011 12:29:45	slew : station keeping manoeuvre half failed
04/10/2011 12:35:07	slew: orbit maintenance manoeuvre #12 bis
11/10/2011 12:35:13	HFI  temperature steps on bolometer PID
12/10/2011 10:30:00	HFI  EOL-Fast IV at 100mK
22/10/2011 14:00:00	solar flare: small event
27/10/2011 12:38:38	therm: SCS TSA setpoint increase
04/11/2011 00:00:00	solar flare: X2 class
07/11/2011 09:00:00	test : pre-EOL-LFER-1 (I_Bias steps)
08/11/2011 10:42:00	HFI  EOL-IBTU (slow VI)
14/11/2011 09:00:00	HFI  2nd pre-EOL-LFER-1 (I_Bias steps) 
14/11/2011 23:58:33	slew: beginning of dwell duration compression phase 
18/11/2011 00:00:00	HFI  EOL-LFER-1 (I_Bias steps) 
26/11/2011 07:00:00	solar flare: Radiation storm and Coronal Mass Ejection
28/11/2011 17:10:00	dtcp: extra pass
07/12/2011 17:00:00	spinup test at 1.4RPM
08/12/2011 10:00:00	planet: HFI Mars scan @ 1.4 RPM
09/12/2011 16:43:00	star tracker unhealthy
16/12/2011 18:35:00	slew: back to scanning law
17/12/2011 18:00:00	planet: HFI Mars scan#3
23/12/2011 15:10:06	He3 flow rate 0 -> 1
25/12/2011 14:45:16	HFI  Add 153.4 uW on the 1.6K stage redundant PID
25/12/2011 20:00:00	solar flare: C-class
27/12/2011 11:42:10	HFI  Temperature steps on the bolometer plate II
29/12/2011 14:24:29	He3 flow rate 1 -> 2
02/01/2012 13:58:00	He3 flow rate 2 -> 3
03/01/2012 14:20:19	HFI  Temperature steps on bolo plate III
04/01/2012 13:52:00	He3 flow rate 3 -> 4
07/01/2012 14:10:00	He3 flow rate 4 -> 5
08/01/2012 07:20:00	slew to Jupiter deep annuli scan
09/01/2012 14:23:00	He3 flow rate 5 -> 6
10/01/2012 04:20:00	planet: HFI Jupiter scan
11/01/2012 14:47:00	He3 flow rate 6 -> 7
14/01/2012 16:00:00	period: end of HFI nominal operations
15/01/2012 14:05:00	HFI  optimisation
16/01/2012 15:00:21	HFI   bolo plate ->110mK
16/01/2012 15:45:09	HFI   bolo plate ->300mK
18/01/2012 15:20:10	HFI  Adjust compression
18/01/2012 16:15:11	HFI  EOL-Fast IV at 300 mK
20/01/2012 19:58:08	HFI  EOL-RAW54 at 300mK
22/01/2012 00:18:00	therm: loss of satellite thermal control
22/01/2012 15:00:00	CDMU PM-A reset
22/01/2012 22:59:58	DPU is rebooted
23/01/2012 05:00:00	solar flare: major one 
25/01/2012 14:45:00	HFI  Adjust compression
27/01/2012 19:00:00	solar flare
30/01/2012 21:53:00	period: slew to survey#6
06/02/2012 14:00:00	HFI  optimisation
07/02/2012 00:00:00	slew: large orbit correction manœuvre
10/02/2012 16:30:00	HFI  EOL-Fast IV at 600 mK
14/02/2012 14:20:00	CDMU PM-A switch over
20/02/2012 10:00:00	HFI  Adjust compression
20/02/2012 14:57:00	slew: touchup manœuvre
21/02/2012 15:00:00	HFI  Adjust compression
21/02/2012 15:16:00	HFI  Adjust compression
22/02/2012 16:50:00	HFI  Adjust compression
23/02/2012 15:20:00	HFI  Adjust compression

(Planck) High Frequency Instrument

European Space Agency

[ESA's] Mission Operation Center [Darmstadt, Germany]

Instrument Operation Team

Daily Tele-Communication Period

(Planck) Low Frequency Instrument

Data Processing Unit

Readout Electronic Unit

Launch & Early Orbit Phase

Junction Field Elect Transistor

Focal Plane Unit

Sorption Cooler Subsystem (Planck)

low frequency excess response

Calibration and Performance Verification

Data Processing Center

Command and Data Management Unit

Attitude Control & Measurement Subsystem (AOCS)

Fiber Optic Gyroscope

Small Gap Recovery

hermal Stabilization Assembly

sudden change of the baseline level inside a ring

End Of Life