[Isocops] Hawaii 21 March 1710
Mark Tapley
mtapley at swri.edu
Mon Mar 21 14:59:02 EDT 2011
All,
hm. Well, if the sun-acq maneuver had
worked perfectly, it would have ended
2011/03:20:23:03:00 pointing us directly at the
sun.
[tapley at ena ~]$ ibex_rotate -o -u 1,0,0 -w ibex-sun -t 2011/03:20:23:03:00
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI +1.000000,+0.000000,+0.000000
which is R.A. +0.000 Decl. +0.000
missing R.A. +359.870 Decl. -0.045 (ibex-sun)
error is R.A. +359.870 Decl. +0.045
for a total 0.137 deg
At the time of the just completed pass,
that pointing (R.A. +359.870 Decl. -0.045
(ibex-sun)) would aim us 0.865 degrees off the
sun:
[tapley at ena ~]$ ibex_rotate -o -r +359.870 -d
-0.045 -w ibex-sun -t 2011/03:21:19:22:00
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI +0.999997,-0.002269,-0.000785
which is R.A. +359.870 Decl. -0.045
missing R.A. +0.666 Decl. +0.292 (ibex-sun)
error is R.A. +359.204 Decl. +0.337
for a total 0.865 deg
Even allowing a 1 degree deadband, we
should be 1.865 deg. off the sun now. The
telemetry Tim sent looks like we are now 2.34
degrees off the sun. Clearly the maneuver
completed, but it looks like the deadband may
have been closer to 1.48 degrees. That's bigger
than we planned; I'll be very interested to see
what the AST says about our spin axis when it
comes back on-line.
Descending is complete at
2011/03:27:02:37:18; at that point, our sun angle
would be 6.081 deg if the sun-acq were perfect.
[tapley at ena ~]$ ibex_rotate -o -r +359.870 -d
-0.045 -w ibex-sun -t 2011/03:27:02:37:18
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI +0.999997,-0.002269,-0.000785
which is R.A. +359.870 Decl. -0.045
missing R.A. +5.468 Decl. +2.335 (ibex-sun)
error is R.A. +354.402 Decl. +2.380
for a total 6.081 deg
Add a 1-degree deadband, and we are OK
(7.081 deg). Add a 1.48 deg deadband, and we are
at 7.56 degrees, which is greater than the 7.25
we have been looking at for a limit (but less
than the angle at which housekeeping telemetry
starts showing adverse effects, as in Orbit 114).
Three-dimensional effects have not been
considered in this, so I would not panic yet.
At 14:27 -0400 3/21/11, Tim Perry wrote:
>All,
> The Hawaii support was failed due to a poor signal quality. The Eb/No
>ranged from 1 to 17 db. Spacecraft looked nominal and the maneuver was
>successful.
>Eb/No: @ 1710 2k 3 to 14 db
> @ 1715 2k 1 to 17 db
> @ 1732 2k 1 to 12 db
>USN PR 10,000
>Razor Issue I100-450 Intermittent data Hawaii 21 Mar 11 1710
>
>
>
>(Embedded image moved to file: pic05436.gif)
>
>Timothy E. Perry
>IBEX, GEMS Mission Ops Lead
>Orbital Sciences Corp
>Space Systems Group
>Office: (703) 406-5976
>Cell: (301) 606-1430
>perry.tim at orbital.com
>
>
>-----------------------------------------
>Notice: This e-mail is intended solely for use of the individual
>or entity to which it is addressed and may contain information that
>is proprietary, privileged and exempt from disclosure under
>applicable law. If the reader is not the intended recipient or
>agent responsible for delivering the message to the intended
>recipient, you are hereby notified that any dissemination,
>distribution or copying of this communication is strictly
>prohibited. This communication may also contain data subject to
>U.S. export laws. If so, that data subject to the International
>Traffic in Arms Regulation cannot be disseminated, distributed or
>copied to foreign nationals, residing in the U.S. or abroad, absent
>the express prior approval of the U.S. Department of State. If
>you have received this communication in error, please notify the
>sender by reply e-mail and destroy the e-mail message and any
>physical copies made of the communication. Thank you.
>
>Attachment converted: Eowyn:pic05436.gif (GIFf/«IC») (00134E02)
>
>Please restrict discussions on this email list to non-ITAR sensitive topics.
>______________________________________________
>Isocops mailing list
>Isocops at lists.sr.unh.edu
>http://lists.sr.unh.edu/mailman/listinfo/isocops
--
- 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.
More information about the Isocops
mailing list