[Isocops] EXT :Re: IBEX Goat Herder for 3 April 2023

[Tyler, Ryan S [US] (SP)]

The star tracker CCD temp being higher could definitely cause more pronounced hot spots that swamp the tracker and make it time out trying to get a lock. MPS is supposed to look at the attitude both before and after the maneuver for outages, so the failure to perform the maneuver shouldn’t result in having Earth in the star tracker FOV. That said, the Earth was pretty close to the star tracker keepout at perigee (late 30th, early 31st… I don’t know exactly when it happened), so it might be that the Earth was about as close as it can be without triggering the keepout in MPS, but maybe the reality of the keepout has changed since the ST software update in 2016. Purely a hypothesis. Either way, the sun was more or less in the opposite direction of the Earth, meaning that the Earth would be fully illuminated for the sake of albedo warming the star tracker. So between the warmth and proximity of the Earth to the keepout, things were apparently just bad enough.

In any case, it might be a good idea to widen the definition of the star tracker keepout by a few deg to avoid this happening again. It also might not be a bad idea to see if DTU would recommend any changes to the star tracker settings, since a lot of time has passed since 2016.


[cid:image001.png at 01D96744.721D2510]


[cid:image002.png at 01D96744.E87FB1A0]

From: Ken Fairchild <kwfairchild at gmail.com>
Sent: Monday, April 3, 2023 9:23 AM
To: ADS-IBEX at l3harris.com
Cc: nangold at princeton.edu; Perry, Timothy E [US] (SP) <Timothy.Perry at ngc.com>; bhautama at gmail.com; carol.weaver at unh.edu; Chubin, Eric [US] (SP) <Eric.Chubin at ngc.com>; IBEXOPS at gmail.com; isocops at lists.sr.unh.edu; fair-play at comcast.net; ken.fairchild at unh.edu; Leonard, Benjamin Y [US] (SP) <Benjamin.Leonard at ngc.com>; angoldconsulting at earthlink.net; Tyler, Ryan S [US] (SP) <Ryan.Tyler at ngc.com>; Wesley, Sheral R [US] (SP) <Sheral.Wesley at ngc.com>; Wynn, Reese [US] (SP) <Reese.Wynn at ngc.com>; Ken Fairchild <kwfairchild at gmail.com>
Subject: EXT :Re: IBEX Goat Herder for 3 April 2023

Nigel,

We currently have 2 theories: 1) that the partial maneuver put us in an outage.  2) Tim noticed the CCD temperature was several degrees higher than normal during the recovery contacts.  This morning it was at its usual temperature.  I think Ryan has.a tool that allows him to visualize if we are in an outage or how close we might be.  I don't know if he can ingest the info from the partial maneuver too...

Unfortunately, I don't think we get the CCD temperature on the ground so we can't look at history.

Ken

On Mon, Apr 3, 2023 at 9:11 AM <ADS-IBEX at l3harris.com<mailto:ADS-IBEX at l3harris.com>> wrote:
Hi all,

I can redo the predicts with the updated maneuvers. Nigel, to clarify, are you wanting an updating star tracker outage report?

I will just need to know whether the perigee inertial maneuver was executed or not – which sounds like the same question that was stated below regarding whether we had any pulses for it.

Thanks!
Kayton

Kayton Lane
Astrodynamics Engineer
Space & airborne systems / L3HARRIS TECHNOLOGIES
w +1 321 729 1809
m +1 218 431 0586
L3Harris.com / Kayton.Lane at L3Harris.com<mailto:Kayton.Lane at L3Harris.com>
Palm Bay, FL 32905 / USA

From: Nigel Angold <nangold at princeton.edu<mailto:nangold at princeton.edu>>
Sent: Monday, April 3, 2023 7:59 AM
To: Perry, Timothy E [US] (SP) <Timothy.Perry at ngc.com<mailto:Timothy.Perry at ngc.com>>
Cc: bhautama at gmail.com<mailto:bhautama at gmail.com>; carol.weaver at unh.edu<mailto:carol.weaver at unh.edu>; Chubin, Eric [US] (SP) <Eric.Chubin at ngc.com<mailto:Eric.Chubin at ngc.com>>; SM[SSTC] - ADS-IBEX <ADS-IBEX at L3Harris.com<mailto:ADS-IBEX at L3Harris.com>>; IBEXOPS at gmail.com<mailto:IBEXOPS at gmail.com>; isocops at lists.sr.unh.edu<mailto:isocops at lists.sr.unh.edu>; fair-play at comcast.net<mailto:fair-play at comcast.net>; kwfairchild at gmail.com<mailto:kwfairchild at gmail.com>; ken.fairchild at unh.edu<mailto:ken.fairchild at unh.edu>; Leonard, Benjamin Y [US] (SP) <Benjamin.Leonard at ngc.com<mailto:Benjamin.Leonard at ngc.com>>; angoldconsulting at earthlink.net<mailto:angoldconsulting at earthlink.net>; Tyler, Ryan S [US] (SP) <Ryan.Tyler at ngc.com<mailto:Ryan.Tyler at ngc.com>>; Wesley, Sheral R [US] (SP) <Sheral.Wesley at ngc.com<mailto:Sheral.Wesley at ngc.com>>; Wynn, Reese [US] (SP) <Reese.Wynn at ngc.com<mailto:Reese.Wynn at ngc.com>>
Subject: [EXTERNAL] Re: IBEX Goat Herder for 3 April 2023

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Thanks, Tim and Ken for working this.

Is there any chance that we were in a partial outage because of the failed maneuver followed by the Sun pointing maneuver instead of the inertial? I’m not sure if that would explain the percent valid bouncing around  like that. But it’s odd that the value was back up to a solid 78-80% last contact.

Did we have any pulses for the failed maneuver?

Would FD running the predicts with the actual attitudes be useful/possible?

Thanks,
Nigel
Sent from my iPhone

On Apr 3, 2023, at 4:13 AM, Perry, Timothy E [US] (SP) <Timothy.Perry at ngc.com<mailto:Timothy.Perry at ngc.com>> wrote:


All,

   The contact was successful. We were able to delete all the timed commands and uplink a new Orbit 603 ATS version 2. On previous contacts we were seeing the star tracker percent valid value jump around from 0 – 80. That was what caused the spacecraft to go into contingence mode during the perigee inertial maneuver. This contact the star tracker percent valid was stable between 78 & 80.



Tasks Accomplished:

Ops Procedure OP924-31423 Delete timed commands

CAR # 1307 Orbit 603 Version 2 ATS uplink

Reset FDC Totals




Timothy E.Perry
CRS IBEX OCO-2
Mission Operations
timothy.perry at ngc.com<mailto:timothy.perry at ngc.com>
Office (703) 406-5976
Cell (301) 606-1430



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