[Isocops] Orbit 109/110 Sun Precession maneuver
Mark Tapley
mtapley at swri.edu
Fri Jan 21 10:57:48 EST 2011
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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