[Isocops] IBEX Orbit# 113 ATS - approve

[Mark Tapley]

All,
	I have looked at the Orbit 113 ATS v001 
(IBEX_2011_041_00_00_v001.txt) and I approve.

	The standard "PL mode unknown at the beginning" constraint 
violation is the only one.

	The PL commands in the ATS v001 appear to match the STF v002 
file (IBEX_2011_041_18_42_v002.stf).

	PL ascending and descending operations make sense WRT 15 Re 
ascending and descending times.

	No Moon in -Lo FOV PMT setback commands. Moon is making other mischief.

	Ground station times match S/C times for all 3 contacts.

	Battery cell balancing is > 1 hour before burn (good). It is 
within 23 minutes after a downlink. Moving it later would make it 
easier to check, but I think it's OK here.

	The sun-pointing maneuver is ACS-SUN. I'm using a 1 degree 
deadband for that (which is conservative). Ibex_rotate says the sun 
vector at the conclusion of the burn (taking the time of the 
thrust-disable command) is R.A. +331.589 Decl. -11.640

[tapley at ena ~]$ ibex_rotate -o -w ibex-sun -t 2011/02:18:15:17:43
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. +331.589 Decl. -11.640 (ibex-sun)
  error is     R.A. +331.589 Decl. +11.640
  for a total  30.518 deg

	In that case, sun angles at the conclusion of the burn 
(expected to be zero), at the Orbit 114 15 Re ascend time, and at the 
Orbit 114 15 Re descend time (per the Orbit 113 .oef) are:

[tapley at ena ~]$ ibex_rotate -o -r +331.589 -d -11.640 -w ibex-sun -t 
2011/02:18:15:17:43
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.861469,-0.466008,-0.201762
  which is     R.A. +331.589 Decl. -11.640
  missing      R.A. +331.589 Decl. -11.640 (ibex-sun)
  error is     R.A.   +0.000 Decl.  +0.000
  for a total  0.000 deg
[tapley at ena ~]$ ibex_rotate -o -r +331.589 -d -11.640 -w ibex-sun -t 
2011-02-18T15:55:19.569Z
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.861469,-0.466008,-0.201762
  which is     R.A. +331.589 Decl. -11.640
  missing      R.A. +331.614 Decl. -11.631 (ibex-sun)
  error is     R.A.   +0.025 Decl.  +0.009
  for a total  0.027 deg
[tapley at ena ~]$ ibex_rotate -o -r +331.589 -d -11.640 -w ibex-sun -t 
2011-02-25T13:45:00.719Z
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.861469,-0.466008,-0.201762
  which is     R.A. +331.589 Decl. -11.640
  missing      R.A. +338.192 Decl.  -9.173 (ibex-sun)
  error is     R.A.   +6.603 Decl.  +2.467
  for a total  6.946 deg

	Burn time (of course) and ascend time are both OK even with a 
1-deg deadband, but descend time would go to 7.946 deg with that 
deadband. To pull that back to a 7.25 degree angle including 
deadband, we need to pick an earlier time to do the descending 
commands. That works out (after some trial and error) to be

2011-02-24T21:00:00.719Z

	at which time Ibex_rotate says the sun angle will be <6.25 
degrees, so we'll be safe even with a 1-degree deadband:

[tapley at ena ~]$ ibex_rotate -o -r +331.589 -d -11.640 -w ibex-sun -t 
2011-02-24T21:00:00.719Z
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.861469,-0.466008,-0.201762
  which is     R.A. +331.589 Decl. -11.640
  missing      R.A. +337.535 Decl.  -9.438 (ibex-sun)
  error is     R.A.   +5.946 Decl.  +2.202
  for a total  6.246 deg

	that loses observations from
2011-02-24T21:00:00.719Z to
2011-02-25T13:45:00.719Z, or 16 hours 45 minutes.

	O-mode coming up orbit 113 as well, so I'll probably have to 
move the O-mode shut-down commands earlier by 16 hours 45 minutes to 
match the PL descending commands.

At 6:20 -0500 2/1/11, Ibex Mission Operations wrote:
>Guys,
>     Here is the ATS for Orbit# 113 which contains a Sun Precession 
>maneuver.  Please review the ATS and send your comments/approval by 
>COB today.

-- 
						- Mark     210-379-4635
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