[Isocops] EXT :Re: IBEX Spacecraft Clock Issue Post-Contact Meeting Notes

Mon Aug 30 11:43:55 EDT 2021

I can answer that question right now: yes, the raw time stamp continues to increment.

See the attached image, which is a screenshot of the secondary header contents. The fields are:
[MAESTRO timestamp in seconds past UNIX time epoch],
[day of year],
[hour],
[subseconds, not used, MSB],
[subseconds, not used, LSB],
[minutes],
[seconds],
[year]

This ground packet is essentially the process by which MAESTRO uses the secondary header to timestamp data. MAESTRO uses columns 2-8 to calculate column 1.

At the time of the event, the timestamp in the secondary header switched from being accurate (sort of – day 602 of year 2020 was correctly translated by MAESTRO) to something completely wrong (day 13948 of year 2026). We’re trying to figure out why that happened and what we can do about it.

MAESTRO apparently rejects a time so far in the future and sets the timestamp to zero every time, thus the static timestamp we’re seeing in MAESTRO. But the fields in the secondary header are indeed incrementing, just from that incorrect epoch.

-Ryan

From: NIgel Angold <nangold at princeton.edu>
Sent: Monday, August 30, 2021 10:41 AM
To: Perry, Timothy E [US] (SP) <Timothy.Perry at ngc.com>; Wynn, Reese [US] (SP) <Reese.Wynn at ngc.com>
Cc: Bobbett, James E [US] (SP) <James.Bobbett at ngc.com>; ISOC at New Hampshire <isocops at lists.sr.unh.edu>; Bachir-Bouiadjra, Benahmed [US] (SP) <Benahmed.Bachir-Bouiadjra at ngc.com>; Conway, Jim [US] (SP) <Jim.Conway at ngc.com>; Leonard, Benjamin Y [US] (SP) <Benjamin.Leonard at ngc.com>; Ken Fairchild UNH (Ken.Fairchild at unh.edu) <Ken.Fairchild at unh.edu>; Dave McComas <dmccomas at princeton.edu>; Bret Hautamaki <bhautama at gmail.com>; Fleming, Ed [US] (SP) <Ed.Fleming at ngc.com>; Wesley, Sheral R [US] (SP) <Sheral.Wesley at ngc.com>; Tyler, Ryan S [US] (SP) <Ryan.Tyler at ngc.com>; Ibex Mission Operations <ibexops at gmail.com>; Ken Fairchild (kwfairchild at gmail.com) <kwfairchild at gmail.com>; Eric Christian <eric.r.christian at nasa.gov>; Cavallo, John A [US] (SP) <John.Cavallo at ngc.com>; Chubin, Eric [US] (SP) <Eric.Chubin at ngc.com>; IBEX FDG Group (ADS-IBEX at l3harris.com) <ADS-IBEX at l3harris.com>; Conway, Jim [US] (SP) <Jim.Conway at ngc.com>; Cross, Walker W [US] (SP) <Walker.Cross at ngc.com>; Varia, Apurva P. (GSFC-5840) <apurva.p.varia at nasa.gov>; Varia, Apurva P. (GSFC-5840) <apurva.p.varia at nasa.gov>
Subject: EXT :Re: [Isocops] IBEX Spacecraft Clock Issue Post-Contact Meeting Notes

Hi Tim, Reese,

Let me know when you've looked at the raw data around when the time stamp went to 1970. I'm very curious to know if the time stamp continued to increment or if it suddenly went to a static value.

Thanks,
Nigel

NIgel Angold<mailto:nangold at princeton.edu>
August 27, 2021 at 11:18
Attendees:
Nigel Angold, Reese Wynn, Carol Weaver, Jim Conway, Ryan Tyler, Ken Fairchild, Bret Hautamaki, Tim Perry, Sheral Wesley, Eric Chubin, Mark Tapley, Walker Cross

16:00-17:00 UTC HI01 contact activities:

  *   Spacecraft health check: nominal except for 1970/01:01:00:00:00 time stamps
  *   Maneuver execution verified
  *   Sent 2 time-tagged commands and verified correct execution:

     *   @fct_tmsoh $time=2021/08:27:16:04:00
     *   @ahw_readSttlmhk $time=2021/08:27:16:05:00

  *   Monitored 2 previously loaded commands executing correctly onboard:

     *   @FCT_SetScState science $TIME=2021/08:27:16:16:33
     *   @CEU_LO_SCIENCE_MODE NORMAL $TIME=2021/08:27:16:16:35

  *   Set the spacecraft clock: no change

Ryan: looks like there's been a jump in the timestamp that MAESTRO can't process.
Jim: Let's look at raw data.
Tim: we are unable to archive data after DOY 236.
Since the spacecraft is functioning nominally, no need for any immediate action. No need to load orbit 540 ATS just yet.

Science: Lo and Hi teams both report nominal-looking orbit 538 data.

Future planning:

  *   20:00 - 21:00 UTC HI01 contact added to dump SSR data and verify correct processing of first ~30 minutes of orbit 539 arc a science data
  *   NG looking at FSW / tables to try to determine possible cause for non-incrementing 1970 time stamp
  *   NG to look at content of raw packets
  *   SOC to look at how the data is time stamped
  *   NG and SOC to report back by email
  *   Follow-up telecon early next week

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