19th gist 27 th -29 th august 2003 e sawyer ral status of gerb1,2,3 and 4 battery issues operations...
TRANSCRIPT
19th GIST 27th-29th August 2003E Sawyer RAL
• Status of GERB1,2,3 and 4• Battery issues• Operations during eclipse• Stray light• NOT bearing life test
19th GIST 27th-29th August 2003E Sawyer RAL
Status• GERB1-
– GERB has been returned for modifications and recalibration.
– Re-calibration first at Imperial– Battery mods, TBC tomorrow.
19th GIST 27th-29th August 2003E Sawyer RAL
Status• GERB2
– In orbit– Switched off for eclipse season– Back on 28th April– Off again now
19th GIST 27th-29th August 2003E Sawyer RAL
Status• GERB3
– Delivered to Alcatel in June– Now integrated onto MSG 3– Will be returned for battery modifications and
calibration check
19th GIST 27th-29th August 2003E Sawyer RAL
Status• GERB4
– ATP received from Eumetsat for 70% funding to match the approval by Eumetsat council.
– Some activities started, parts procurement, detector blacking.
– Some electronics manufacture will start at RAL.
– Most subsystems will kick of Jan 04.
19th GIST 27th-29th August 2003E Sawyer RAL
Battery
• Proposals have been discussed with ESA that enable safe switch down without battery power, these have been assessed by Alcatel.
• Agreement has now been reached on the implementation, a kick-off meeting for GERB 1 will be held tomorrow.
• Relatively simple modifications will be incorporated and the unit re-qualified.
• GERB 3 will undergo similar treatment.
19th GIST 27th-29th August 2003E Sawyer RAL
Battery continued
• GERB on MSG1 has no battery assisted power down capability
• GERB software patch has been coded to detect sun close to the field of view and perform safe switch down, first test failed, some more work to do.
• Eumetsat may be able to modify MSG software to minimise risk to GERB in the event of a spacecraft emergency. The schedule for this is not defined
19th GIST 27th-29th August 2003E Sawyer RAL
Eclipse
• First Sun avoidance period started 12 February
• No battery safe switch down
• GERB switched to SAFE mode
• No MSG modified software
• There was one unplanned switch off of GERB during this period
• Strategy for next eclipse period (end August to end Oct) is to switch down to SUNBLOCK mode
• Current plan is that during eclipse periods, GERB will be in SUNBLOCK mode for approximately 5 hours.
19th GIST 27th-29th August 2003E Sawyer RAL
Stray light• Two issues
– Contamination when sun is close to FOV
– Contamination due to sun illumination of Black Body.