[Isocops] Orbit 109/110 Sun Precession maneuver

[Nathan Schwadron]

Great work, everyone!!

On Jan 21, 2011, at 11:09 AM, Reno, Michelle wrote:

> Excellent. We can all sit back and relax now.
>  
> Until the next sun-pointing maneuver in orbit 113/114. :)
>  
>  
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Chelle Reno
> Austin Mission Consulting
> (210) 478-7337 (c)
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> From: Mark Tapley [mailto:mtapley at swri.edu]
> Sent: Fri 1/21/2011 9:57 AM
> To: Reno, Michelle; Sheral Wesley; Tim Perry; Tyler.Ryan at orbital.com; Walker Cross; isocops at lists.sr.unh.edu; Lisa Policastri; Ryan Lebois; Marissa Intelisano
> Cc: lockwood.robert at orbital.com; Scherrer, John
> Subject: RE: Orbit 109/110 Sun Precession maneuver
> 
> At 1:00 PM -0600 1/19/11, Reno, Michelle wrote:
> >Hello,
> >
> >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
> 
> We are good to go.
> 
> I tried both  the quaternion
> 0.41869900,0.70158400,-0.28378800,0.50193100 (yellow) and the "spin
> axis" vector 0.466650,-0.818519,-0.335059 from Tim's email (purple) -
> same answer (good).
> 
> Sun angle at the 15 Re descending crossing on the 26th very near
> all-balls would be a problem:
> 
> [tapley at ena ~]$ ibex_rotate -o -u 0.466650,-0.818519,-0.335059 -w
> ibex-sun -t 2011-01-26T00:00:15.740Z
> Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
>   points axis  +1.000000,+0.000000,+0.000000
>   towards ECI  +0.466650,-0.818519,-0.335059
>   which is     R.A. +299.688 Decl. -19.576
>   missing      R.A. +307.852 Decl. -18.920 (ibex-sun)
>   error is     R.A.   +8.164 Decl.  +0.656
>   for a total  7.734 deg
> 
> But at the time we have the PL coming down 13 hours earlier on the
> 25th we will be OK:
> 
> [tapley at ena ~]$ ibex_rotate -o -u 0.466650,-0.818519,-0.335059 -w
> ibex-sun -t 2011/01:25:10:32:44Quaternion
> +0.000000,+0.000000,+0.000000,+0.000000
>   points axis  +1.000000,+0.000000,+0.000000
>   towards ECI  +0.466650,-0.818519,-0.335059
>   which is     R.A. +299.688 Decl. -19.576
>   missing      R.A. +307.253 Decl. -19.067 (ibex-sun)
>   error is     R.A.   +7.565 Decl.  +0.509
>   for a total  7.156 deg
> 
> All clear on that issue, I believe.
> 
> 
> --
>                                                 - Mark     210-379-4635
> -----------------------------------------------------------------------
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Nathan Schwadron
n.schwadron at unh.edu

University of New Hampshire
Morse Hall - Room 353
8 College Road
Durham NH 03824
USA

(603) 862-3451



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