[Isocops] Orbit 109/110 Sun Precession maneuver

[Reno, Michelle]

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
-----------------------------------------------------------------------
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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