[Isocops] Quaternions post pointing burn

[Reno, Michelle]

Thanks Mark. I agree we should leave the current DESCENDING times; 7.64 degrees off sun pointing is higher than desired (7.5 degree planning limit) but less than the actual max limit of 8.0 degrees. 
 
Hi or Lo, please speak up by noon 6/29 if you are uncomfortable with this. The only planned opportunity to change these is the apogee contact early on 6/30.
 
Chelle
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Chelle Reno
Austin Mission Consulting
106 E. 6th St. Ste. 939
Austin, TX  78701
(512) 704-3394 (o)
(210) 478-7337 (c)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

________________________________

From: Mark Tapley [mailto:mtapley at swri.edu]
Sent: Mon 6/28/2010 2:05 PM
To: isocops at lists.sr.unh.edu
Cc: michelle.reno at swri.org
Subject: Quaternions post pointing burn



All,
        Chelle asked me to look at the pointings subsequent to
delivery of the quaternion resulting from the sun-pointing burn.

        From the Goat Herder orbit 82 which Tim emailed:

Q1      -0.15279000     ActNor.EstInrToBdy[0]
Q2      -0.52037700     ActNor.EstInrToBdy[1]
Q3      -0.78616500     ActNor.EstInrToBdy[2]
Q4      0.29632300      ActNor.EstInrToBdy[3]

        Checking how close the maneuver was to pointing at the sun:

[tapley at ena ~]$ ibex_rotate -o -z
-0.15279000,-0.52037700,-0.78616500,0.29632300, -w ibex-sun -t
2010-06-27T10:55:12.782Z
Quaternion    -0.152790,-0.520377,-0.786165,+0.296323
  points axis  +0.000000,+0.000000,+1.000000
  towards ECI  -0.068163,+0.908755,+0.411726
  which is     R.A.  +94.290 Decl. +24.313
  missing      R.A.  +96.080 Decl. +23.340 (ibex-sun)
  error is     R.A.   +1.791 Decl.  +0.974
  for a total  1.906 deg

        this agrees with the Goat herder, which says 1.901 degrees.
Hmmm, not very close.
        If we look at the situation at the time of descending macros,
taking that time from the STF (looking at the last of the commands),


[tapley at ena ~]$ ibex_rotate -o -z
-0.15279000,-0.52037700,-0.78616500,0.29632300, -w ibex-sun -t
2010-07-03T15:10:51.000Z
Quaternion    -0.152790,-0.520377,-0.786165,+0.296323
  points axis  +0.000000,+0.000000,+1.000000
  towards ECI  -0.068163,+0.908755,+0.411726
  which is     R.A.  +94.290 Decl. +24.313
  missing      R.A. +102.498 Decl. +22.926 (ibex-sun)
  error is     R.A.   +8.209 Decl.  +1.387
  for a total  7.647 deg

7.647 degrees should still be OK, though close. I would say let it
ride, unless -Hi or -Lo teams are not happy with that big an angle.

--
                                                - Mark     210-379-4635
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inhabited by beings that don't have
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