[Isocops] [Isocdev] Fwd: High resolution (oxygen mode) test during lunarviewing

Mark Tapley mtapley at swri.edu
Wed Jun 9 16:49:16 EDT 2010


Chelle,
	sorry, my previous email was not too clear. The second set of 
sun angles was determined assuming that the SC was pointed directly 
at the sun at the maneuver start time (as you list below). So the 
fact that that set stays < 6.5 degrees means even with a 1-degree off 
sun-pointing at the start (not end) of the maneuver I think means we 
are Ok in worst case.

	I used:

ibex_rotate -o -r +95.447 -d +23.358 ibex-sun -t 2010-06-26T20:50:36.000Z

	To get the sun vector at the time of the maneuver, then

ibex_rotate -o -r +95.447 -d +23.358 ibex-sun -t 2010-07-01T14:00:00.000Z
ibex_rotate -o -r +95.447 -d +23.358 ibex-sun -t 2010-07-01T24:00:00.000Z
ibex_rotate -o -r +95.447 -d +23.358 ibex-sun -t 2010-07-03T15:00:00.000Z

	to get the lower set of numbers, ending at 6.491 degrees.


At 15:11 -0500 6/9/10, Reno, Michelle wrote:
>Hey Mark,
>
>The sunpointing vector will unfortunately not put us on the 
>RepointingTargetVector in the OEF. That target vector is used only 
>for the inertial repointing maneuvers done by the star trackers. The 
>sun pointing maneuvers are done by the course sun sensor and do not 
>accept target vectors - they just point at the sun when you send the 
>ACS_SUN command and enable thrusters.
>
>We will begin pointing at the sun (plus slop for ACS deadband) at
>
>06/26/10 20:50:36 Maneuver Start time
>
>Please re-verify our pointing at the DESC commands using this info.
>
>Thanks,
>Chelle
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Chelle Reno
>Austin Mission Consulting
>106 E. 6th St. Ste. 939
>Austin, TX  78701
>(512) 704-3394 (o)
>(210) 478-7337 (c)
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>From: isocdev-bounces at lists.sr.unh.edu on behalf of Mark Tapley
>Sent: Wed 6/9/2010 2:34 PM
>To: Nathan Schwadron
>Cc: isocops at lists.sr.unh.edu; isocdev at lists.sr.unh.edu
>Subject: Re: [Isocdev] Fwd: High resolution (oxygen mode) test 
>during lunarviewing
>
>Nathan,
>         Sorry, just dug back to this message now. Looks like Greg
>responded with syntax, timing, etc.
>
>         The sun-pointing maneuver is between 10 and 15 Re, not 3 Re.
>
>         If the sun-pointing maneuver puts us directly on the pointing
>vector given in the .oef,
>
>2010-06-27T10:53:04.828Z,RepointingTargetVector,vtsX:-0.09713517962079862,orbit:83,vtsZ:0.3961860371665777,vtsY:0.9130177330338543
>
>
>         then ibex_rotate shows sun angles as follows:
>
>2010-07-01T14:00:00.000Z        +4.000
>2010-07-01T24:00:00.000Z        +4.395
>2010-07-03T15:00:00.000Z        +5.916
>
>         No problem, even if we add in a 1 degree deadba! nd error. 
>sp;    If the sun-pointing maneuver points us directly at the sun,
>then ibex_rotate shows:
>
>2010-07-01T14:00:00.000Z        4.575 deg
>2010-07-01T24:00:00.000Z        4.970 deg
>2010-07-03T15:00:00.000Z        6.491 deg
>
>         Still OK, but worst-case 1 degree deadband is now dicey
>(total 7.491 degrees from sun). But considering this is worst-case, I
>think we are OK.
>
>
>
>>Hey Mark
>>
>>It looks like you are digging into the IBEX ops and starting to
>>understand our chaos. Well done!
>>
>>Could you please verify the stuff below (Manuever times and sun
>>pointing at the end of the message).
>>
>>Also, I need to find out if the syntax is correct for the message I
>>sent to Greg ..
>>
>
>--
>       &nbs! p;   nbsp;                                  - Mark 
>210-379-4635
>-----------------------------------------------------------------------
>Large Asteroids headed toward planets
>inhabited by beings that don't have
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>
>                                 Think of it as Evolution in Fast-Forward.
>
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-- 
						- 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.



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