[Isocops] Orbit 109/110 Sun Precession maneuver

Reno, Michelle mreno at swri.edu
Wed Jan 19 14:00:24 EST 2011

Tim verified in last night's 0600 pass that the sun precession maneuver executed and the spacecraft is nominal. We are still in a 100% outage so two tasks remain: 
1) verify the off-sun pointing angle is less than 7.25 when the payload descends (info from 1/21 0230 pass), and
2) execute static Z rate CAR on 1/22 apogee pass.
Below is a breakdown of task by pass. Attached is the updated sun recession maneuver timeline.
Date	 Time	 Event	 Details and *Actions	 Complete	
 	 06:38	 Payload ASCENDING - 15Re asc	  	 ?	
 	  	 Lo enters OXYGEN mode	  	 ?	
1/20/2011	 20:51	 Star Tracker Outage Stop	 25% valid	  	
 	 23:42	 Star Tracker Outage Stop	 50% valid	  	
1/21/2011	 02:30	 HAW02 calibration pass	 2ksps; 
* Tim check pointing vector - email out right after pass
* Mark verify off-sun pointing at time of DESCENDING commands < 7.25 degrees
* Mark email whether new DESCENDING commands needed	  	
 	 04:27	 Star Tracker Outage Stop	 75% valid	  	
 	 19:11	 Star Tracker Outage Stop	 100% valid	  	
1/22/2011	 00:01	 apogee/post-burn pass	 2ksps;
* CAR 337: Set static z-rate, verify ACS performance
* CAR nnn: upload new DESCENDING commands (if needed)	  	
Chelle Reno
Austin Mission Consulting
(210) 478-7337 (c)


From: Reno, Michelle
Sent: Thu 1/6/2011 4:37 PM
To: Sheral Wesley; Tim Perry; Tyler.Ryan at orbital.com; Walker Cross; isocops at lists.sr.unh.edu; Lisa Policastri; Ryan Lebois; Marissa Intelisano; Reno, Michelle
Cc: lockwood.robert at orbital.com; Scherrer, John
Subject: Orbit 109/110 Sun Precession maneuver

Hey folks,
I put together a detailed timeline for the upcoming sun precession maneuver. It includes a chart of when the star tracker outages occur wrt other things of interest (apogee, perigee, Lo entering O-mode, etc). Please note that there is only a line item per event of interest, so time duration is not visually represented. 
The special activities that need to be performed during/directly after the passes are included (Mark, Tim, Sheral these are for you). Hopefully we can use the HAW02 calibration pass to determine if we need to send the DESCENDING commands earlier. That will give us time to generate the new STF/ATS prior to the apogee pass (being rescheduled, updates on exact time will be sent out later).
Bonus: looks like there is a day in orbit 109 where we will not be in an outage.
Let me know if this is useful. I can produce something similar for the orbit 113/114 maneuver.
% valid FYI
Included are the start/stop of the outage per the 100, 75, 50 & 25% marks assessed by FDG. For planning we use 100% valid as the 'official' start/stop of the outage, 90% needed to set the static-Z rate after a sun precession maneuver, 50% needed to perform an inertial precession maneuver. 
On-orbit the Attitude Control System changes it's method of calculating the spin pulse by the % valid (configurable in each ATS): 
* 100- 85% quaternions only. 
* 85-18% quaternions + static-Z rate (a measured constant - the spin rate taken 15min after thrusters disabled each orbit)
* 18 - 0 - 23% static Z-rate only
* 23- 90% quaternions + static-Z rate 
* > 90% quaternions only
Chelle Reno
Austin Mission Consulting
(210) 478-7337 (c)
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