[Isocops] IBEX Orbit# 109 ATS - approve

[Mark Tapley]

All,
	I have looked at the Orbit 109 ATS v001 
(IBEX_2011_011_00_00_v001.txt) and I approve.

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

	The PL commands match the STF v001 file 
(IBEX_2011_011_15_53_v001.stf) per Ken's script (thanks again, Ken!).

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

	Ground station times not included, but the S/C times are 
sensible including the time for the post-burn contact.

	Battery cell balancing is > 1 hour from anything.

	The sun-pointing maneuver this time is an ACS-sun burn. I'm 
using a 1 degree deadband for that (which is conservative). (Nathan, 
let me know if you want something smaller.) Ibex_rotate says the sun 
vector at the conclusion of the burn (taking the time of the 
thrust-disable command) is R.A. +300.769 Decl. -20.415

[tapley at ena ~]$ ibex_rotate -o -w ibex-sun -t 2011/01:19:06:01:30
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. +300.769 Decl. -20.415 (ibex-sun)
  error is     R.A. +300.769 Decl. +20.415
  for a total  61.351 deg

	In that case, sun angles at the conclusion of the burn 
(expected to be zero), at the Orbit 110 15 Re ascend time, and at the 
Orbit 110 15 Re descend time (per the Forecast .oef) are:

[tapley at ena ~]$ ibex_rotate -o -r +300.769 -d -20.415 -w ibex-sun -t 
2011/01:19:06:01:30
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.479446,-0.805269,-0.348817
  which is     R.A. +300.769 Decl. -20.415
  missing      R.A. +300.769 Decl. -20.415 (ibex-sun)
  error is     R.A.   +0.000 Decl.  +0.000
  for a total  0.000 deg
[tapley at ena ~]$ ibex_rotate -o -r +300.769 -d -20.415 -w ibex-sun -t 
2011-01-19T06:38:51.327Z
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.479446,-0.805269,-0.348817
  which is     R.A. +300.769 Decl. -20.415
  missing      R.A. +300.796 Decl. -20.409 (ibex-sun)
  error is     R.A.   +0.027 Decl.  +0.006
  for a total  0.026 deg
[tapley at ena ~]$ ibex_rotate -o -r +300.769 -d -20.415 -w ibex-sun -t 
2011-01-25T23:56:12.033Z
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.479446,-0.805269,-0.348817
  which is     R.A. +300.769 Decl. -20.415
  missing      R.A. +307.849 Decl. -18.921 (ibex-sun)
  error is     R.A.   +7.080 Decl.  +1.494
  for a total  6.831 deg

	Burn time (of course) and ascend time are both OK even with a 
1-deg deadband, but descend time would go to 7.831 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

2011-01-25T10:32:12.033Z

	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 +300.769 -d -20.415 -w ibex-sun -t 
2011-01-25T10:32:12.033Z
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.479446,-0.805269,-0.348817
  which is     R.A. +300.769 Decl. -20.415
  missing      R.A. +307.253 Decl. -19.068 (ibex-sun)
  error is     R.A.   +6.484 Decl.  +1.347
  for a total  6.249 deg

	that loses observations from  10:32:12.033Z to 23:56:12.033Z, 
or 13 hours 24 minutes.

	O-mode coming up orbit 110 as well, so I'll probably have to 
move the O-mode shut-down commands earlier by 13.4 hours to match the 
PL descending commands.

At 13:38 -0500 12/30/10, Ibex Mission Operations wrote:
>Guys,
>    Here are the planning files for Orbit# 109.
>I have included the ABS for the Sun Precession Maneuver that occurs 
>14 Re Asc  19 Jan 11 @05:46:20 for 15 minutes
>Please review the ATS for approval/comments before 31 Dec 10.

-- 
						- Mark     210-379-4635
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