Note: Angle at orbit 471 arc B descending after the apogee sun precession maneuver: 4.247 deg

I have looked at the orbit 471 ATS,

IBEX_2019_351_o0471a_v001.scr,

and I approve.

The only constraint violations in

IBEX_2019_351_o0471a_v001.ccvr

are from the removal of the

ACT_SetSpinPulseProtectEnable Enable

commands (2), the proximity of contacts and the eclipse; the violations are expected.

The PL commands in the v001 ATS match those in the v002 STF,

IBEX_2019_351_o0471a_v002.stf.

Ascending and descending command sequences are consistent with each other, 15 Re ascending, the apogee maneuver time and 15 Re descending as determined from the OEF,

IBEX_2019_351_o0471a_v001.oef,

and as verified with ibex_orbit.

There is one star tracker outage. The outage starts 2- days after 15 Re ascending and runs for 3+ days. Some despinning may be required due to this outage.

The ground station command sequences are correct and the timing and bit rates match those in the contacts file,

IBEX_Orbit471_Contacts.txt,

for all contacts (5).

We are not doing battery cell balancing this orbit - there is an eclipse near perigee.

The inertial maneuver at perigee of orbit 470 left us pointing in safe directions for the orbit 471 arc A ascending and descending sequences:

ibex_rotate -o -u -0.069298,-0.911205,-0.406083 -w ibex-sun -t 2019/12:17:19:31:14

Quaternion. +0.000000,+0.000000,+0.000000,+0.000000

points axis +1.000000,+0.000000,+0.000000

towards ECI -0.069298,-0.911205,-0.406083

which is R.A. +265.651 Decl. -23.959

missing R.A. +264.897 Decl. -23.375 (ibex-sun)

error is R.A. +0.754 Decl. +0.584

for a total 0.905 deg

ibex_rotate -o -u -0.069298,-0.911205,-0.406083 -w ibex-sun -t 2019/12:21:22:49:36

Quaternion +0.000000,+0.000000,+0.000000,+0.000000

points axis +1.000000,+0.000000,+0.000000

towards ECI -0.069298,-0.911205,-0.406083

which is R.A. +265.651 Decl. -23.959

missing R.A. +269.429 Decl. -23.430 (ibex-sun)

error is R.A. +3.778 Decl. +0.529

for a total 3.500 deg

The sun precession maneuver at apogee leaves us pointing in safe directions at the time of the maneuver and for arc B ascending and descending sequences:

ibex_rotate -o -r +269.511 -d -23.429 -w ibex-sun -t 2019/12:22:00:37:44

Quaternion +0.000000,+0.000000,+0.000000,+0.000000

points axis +1.000000,+0.000000,+0.000000

towards ECI -0.007831,-0.917520,-0.397612

which is R.A. +269.511 Decl. -23.429

missing R.A. +269.511 Decl. -23.429 (ibex-sun)

error is R.A. +0.000 Decl. +0.000

for a total 0.000 deg

ibex_rotate -o -r +269.511 -d -23.429 -w ibex-sun -t 2019/12:22:02:07:50

Quaternion +0.000000,+0.000000,+0.000000,+0.000000

points axis +1.000000,+0.000000,+0.000000

towards ECI -0.007831,-0.917520,-0.397612

which is R.A. +269.511 Decl. -23.429

missing R.A. +269.579 Decl. -23.428 (ibex-sun)

error is R.A. +0.068 Decl. +0.001

for a total 0.062 deg

ibex_rotate -o -r +269.511 -d -23.429 -w ibex-sun -t 2019/12:26:04:39:19

Quaternion +0.000000,+0.000000,+0.000000,+0.000000

points axis +1.000000,+0.000000,+0.000000

towards ECI -0.007831,-0.917520,-0.397612

which is R.A. +269.511 Decl. -23.429

missing R.A. +274.138 Decl. -23.363 (ibex-sun)

error is R.A. +4.627 Decl. +0.066

for a total 4.247 deg

The inertial maneuver at perigee leaves us pointing in safe directions at the time of the maneuver and at orbit 472 apogee:

ibex_rotate -o -u 0.09429,-0.909322,-0.405269 -w ibex-sun -t 2019/12:26:07:46:03

Quaternion +0.000000,+0.000000,+0.000000,+0.000000

points axis +1.000000,+0.000000,+0.000000

towards ECI +0.094290,-0.909322,-0.405269

which is R.A. +275.920 Decl. -23.908

missing R.A. +274.291 Decl. -23.365 (ibex-sun)

error is R.A. +1.629 Decl. +0.543

for a total 1.588 deg

ibex_rotate -o -u 0.09429,-0.909322,-0.405269 -w ibex-sun -t 2019-12-31T05:39:55.908Z

Quaternion +0.000000,+0.000000,+0.000000,+0.000000

points axis +1.000000,+0.000000,+0.000000

towards ECI +0.094290,-0.909322,-0.405269

which is R.A. +275.920 Decl. -23.908

missing R.A. +279.746 Decl. -23.127 (ibex-sun)

error is R.A. +3.826 Decl. +0.781

for a total 3.594 deg

No Lo O-mode.

There is no overlap with orbit 470 commands by manual inspection or by checking at

http://ibex.unh.edu/cgi-bin/ats.cgi.

Command Approval Checklist is attached.

Ken

All,

I have attached the planning files for Orbit# 471

Please respond to this email thread with your comments and approvals.

Approvals are required by COB 6 Dec 19

Please note the following:

1. Moderate Eclipse

# ORBIT$ 471 PERIGEE: Eclipse Commands

# 2019-12-26T12:47:44.059Z,PenumbraEntry,orbit:471

# 2019-12-26T12:47:44.059Z,EclipseEntry,moderate:true,long:false,orbit:471

# 2019-12-26T14:06:34.424Z,PenumbraExit,orbit:471

# 2019-12-26T14:06:34.424Z,EclipseExit,moderate:true,long:false,orbit:471

SetLongEclipseFlag TRUE $TIME=2019/12:26:10:45:00

SetLongEclipseFlag FALSE $TIME=2019/12:26:14:10:00

2. Command Load Constraint Violation Report

IBEX_2019_351_o0471a_v001.scr

==========================

HARD CONSTRAINT VIOLATIONS

==========================

NO VIOLATIONS.

==========================

SOFT CONSTRAINT VIOLATIONS

==========================

IBX-CLC-006: Planned transmission at 2019/12/17 16:58:00 UTC - 2019/12/17

18:02:00 UTC is followed by one or more additional transmissions

which, when combined, exceed the maximum transmission time of 5400

seconds within a 18000-second window (total planned transmission

time this window is 7680.000 seconds)

IBX-CLC-006: Planned transmission at 2019/12/17 19:58:00 UTC - 2019/12/17

21:02:00 UTC is preceded by one or more additional transmissions

which, when combined, exceed the maximum transmission time of 5400

seconds within a 18000-second window (total planned transmission

time this window is 7680.000 seconds)

* SSR_Dump/Tracking Contact 17 Dec 19 @1658z - 1802z

* IBEX Hi- BAckground TEst 17 Dec 19 @1958z - 2102z

IBX-CLC-015: Battery charge falls below minimum from 2019/12/26 13:41:44 UTC -

2019/12/26 15:04:34 UTC. Lowest charge level is 6353.767108

watt-minutes during this interval.

* ORBIT# 471 PERIGEE: Eclipse Commands

# 2019-12-26T12:47:44.059Z,PenumbraEntry,orbit:471

# 2019-12-26T12:47:44.059Z,EclipseEntry,moderate:true,long:false,orbit:471

# 2019-12-26T14:06:34.424Z,PenumbraExit,orbit:471

# 2019-12-26T14:06:34.424Z,EclipseExit,moderate:true,long:false,orbit:471

SetLongEclipseFlag TRUE $TIME=2019/12:26:10:45:00

SetLongEclipseFlag FALSE $TIME=2019/12:26:14:10:00

IBX-CLC-016: No command to enable spin pulse protection was found after

transition to science mode at 2019/12/17 16:59:35 UTC

IBX-CLC-016: No command to enable spin pulse protection was found after

transition to science mode at 2019/12/22 01:37:50 UTC

==============

OTHER MESSAGES

==============

NO MESSAGES.

Thanks,

Sheral R. Wesley

Principal Engr. Satellite Systems

ICESat-2 Mission OPS Lead

IBEX , OCO2 Mission OPS

CRS/CYGNUS Mission Planning

Northrop Grumman Innovation Systems

Bldg. 2 Room 1337

Cell (202) 236-0802