[Isocops] FW: [Ibex-soc] IBEX Orbit# 87 ATS (27 July - 4 Aug 10)
Reno, Michelle
mreno at swri.edu
Fri Jul 16 14:12:50 EDT 2010
________________________________
From: Ryan Lebois [mailto:rlebois at applieddefense.com]
Sent: Fri 7/16/2010 12:55 PM
To: Mark Tapley
Cc: Michelle Reno; Sheral Wesley; Lisa Policastri
Subject: Re: [Ibex-soc] IBEX Orbit# 87 ATS (27 July - 4 Aug 10)
Mark,
While I cannot explain the difference in the outage times for the short oef and forecast oef, I feel like this outage has come up enough to warrant a little more explanation. I am attaching some brief notes on the outage and 2 plots that tell the story of what we're seeing. If you have any more questions about the actual outage feel free to let me know and I'll do my best to answer them.
The only thing I can think of for the oef difference would be something to do with the start time selected for creating the short oef. The fact that the outage start time is an even minute is something I have seen before when the short oef starts in the middle of an outage. However, I don't think this explains the strange Moon outage times that it adds in... All I can conclude is that the FDG model shows two distinct outages as described in the attached notes and the latest Star Tracker Outage reports, and neither of these outages appear to be a problem.
Ryan Lebois
IBEX Flight Dynamics
On Thu, Jul 15, 2010 at 5:58 PM, Mark Tapley <mtapley at swri.edu> wrote:
At 11:46 -0400 7/15/10, Ibex Mission Operations wrote:
Please review the ATS for Orbit# 87
I have included the battery balancing commands
Approval/comments for the ATS are needed by COB Friday, 16 July 10
The ATS will be uploaded during one of the Orbit# 85 perigee contacts listed below in UTC
IBEX,USAK01,ADD,07/19/10,200,11:00:00,07/19/10,200,12:10:00,,LAHO 160K IBEX Orbit# 85 SSR_Dump/Tracking
IBEX,USHI01,ADD,07/20/10,201,07:30:00,07/20/10,201,08:05:00,,LAHO 2K IBEX Orbit# 85 Tracking Contact
Sheral,
looked over the attached files. One interesting thing caught my eye. The short .oef file, IBEX_2010_Orbit87_v001.oef, says:
2010-07-27T02:00:00.000Z,StarTrackerOutageStart,orbit:86,dueTo:overlap
2010-07-27T07:16:33.245Z,Perigee,orbit:86
2010-07-27T07:31:48.185Z,StarTrackerOutageStart,orbit:86,dueTo:moon
2010-07-27T07:41:44.932Z,StarTrackerOutageStop,orbit:86,dueTo:overlap
2010-07-27T10:39:28.379Z,StarTrackerOutageStop,orbit:86,dueTo:moon
but the Forecast .oef file, IBEX_2010_Forecast_15July10-23Oct10_v001.oef, says:
2010-07-26T02:25:23.395Z,StarTrackerOutageStart,orbit:86,dueTo:overlap
2010-07-26T21:40:10.652Z,15RECrossing,direction:desc,orbit:86
2010-07-27T01:39:55.832Z,10RECrossing,direction:desc,orbit:86,oMode:0
2010-07-27T07:16:33.245Z,Perigee,orbit:86
2010-07-27T07:35:19.913Z,StarTrackerOutageStop,orbit:86,dueTo:overlap
With the short file claiming the outage lasts a lot longer, up to 10:39:28. This is interesting because according to the o0086 ATF, the repointing maneuver starts in between the two times (but not much, almost to the end of even the later prediction):
@ACT_SetThrustEnable ENABLE $TIME=2010/07:27:10:38:22
@ACT_SetThrustEnable DISABLE $TIME=2010/07:27:10:53:22
******
How are the star tracker outage times calculated differently between the two files?
******
Ken reports that the instrument commands match the STF, good.
Ascending and Descending commands match up with 15 Re times, good.
Ground contact times match the transmitter on times, good.
According to ibex_rotate, sun angles at the time of the inertial maneuver, at the next Ascending 15 Re crossing, and at the next descending 15 Re crossing are all good (1.01, 0.435, and 6.228 degrees respectively):
[tapley at ena ~]$ ibex_rotate -o -u -0.6709580708861025,0.6801661773297624,0.2952782388348625 -w ibex-sun -t 2010/08:03:17:20:27
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI -0.670958,+0.680166,+0.295278
which is R.A. +134.610 Decl. +17.174
missing R.A. +133.593 Decl. +17.418 (ibex-sun)
error is R.A. +1.017 Decl. +0.244
for a total 1.001 deg
[tapley at ena ~]$ ibex_rotate -o -u -0.6709580708861025,0.6801661773297624,0.2952782388348625 -w ibex-sun -t 2010-08-04T08:22:39.899Z
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI -0.670958,+0.680166,+0.295278
which is R.A. +134.610 Decl. +17.174
missing R.A. +134.172 Decl. +17.292 (ibex-sun)
error is R.A. +0.438 Decl. +0.118
for a total 0.435 deg
[tapley at ena ~]$ ibex_rotate -o -u -0.6709580708861025,0.6801661773297624,0.2952782388348625 -w ibex-sun -t 2010-08-11T06:12:31.549Z
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI -0.670958,+0.680166,+0.295278
which is R.A. +134.610 Decl. +17.174
missing R.A. +140.798 Decl. +15.307 (ibex-sun)
error is R.A. +6.189 Decl. +1.867
for a total 6.228 deg
[tapley at ena ~]$
Pending being convinced that star tracker outage times are OK, I'll approve.
--
- Mark 210-379-4635
-----------------------------------------------------------------------
Large Asteroids headed toward planets
inhabited by beings that don't have
technology adequate to stop them:
Think of it as Evolution in Fast-Forward.
--
Ryan Lebois
Applied Defense Solutions
rlebois at applieddefense.com
Office 301.483.4910
Mobile 410.251.0954
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