[Isocops] EXT :Re: IBEX Goat Herder for 3 April 2023
Geoff Crew
gbc at haystack.mit.edu
Wed Apr 5 09:22:00 EDT 2023
(2 cents)
I'm skeptical a few degrees would make a difference (unless something
very nonlinear is going on).
However, the CCDs have been on orbit a very long time and radiation
damage is a thing. Chandra (which has a high apogee orbit) and uses
(different) CCDs in its x-ray instrument encountered some significant
radiation damage which was eventually repaired through a temperature
cycling procedure. So yes, I'd heartily recommend the follow-up to DTU.
On 4/4/23 22:29, Tyler, Ryan S [US] (SP) wrote:
>
> 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 30^th , early 31^st … 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.
>
> *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> 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>
> *Sent:* Monday, April 3, 2023 7:59 AM
> *To:* Perry, Timothy E [US] (SP) <Timothy.Perry at ngc.com>
> *Cc:* bhautama at gmail.com; carol.weaver at unh.edu; Chubin, Eric [US]
> (SP) <Eric.Chubin at ngc.com>; SM[SSTC] - ADS-IBEX
> <ADS-IBEX at L3Harris.com>; IBEXOPS at gmail.com;
> isocops at lists.sr.unh.edu; fair-play at comcast.net;
> kwfairchild at gmail.com; 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>
> *Subject:* [EXTERNAL] Re: IBEX Goat Herder for 3 April 2023
>
> *WARNING: *Email originated from an *EXTERNAL* source. Do NOT
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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> 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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--
Geoff Crew
gbc at haystack.mit.edu
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