ACIS Shutdown Checklist

Table of Contents

  1. Introduction

  2. Shutdown Checklist


1. Introduction

This document provides a quick checklist to follow in the case of a Spacecraft shutdown - either an SCS-107-only or Full Stop.

With a "Full Stop" shutdown, SCS-107 is executed and both the science and vehicle loads are stopped.
The thermal response of the spacecraft is mainy driven by its orientation (mainly pitch).

With an SCS-107-only shutdown only the science loads are stopped. The vehicle loads continue to execute and the thermal response of the
spacecraft is similar to the loads's planned response.

Shutdowns can be either due to radiation events - solar storms - or spacecraft hardware generated (e.g. momentum).

Radiation shutdowns can be either manually commanded from the ground or autonomous via the ACIS Txings monitor.

As of this writing, when an SCS-107 is executed, ACIS is stowed under cover, the ACIS video boards and FEPs are powered down,
and then three (3) FEP PC boards are powered-up to prevent the FEP and BEP boards from getting too cold.

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2. Shutdown Checklist

  1. Get on the telecon
    2. Typically this is     Anomaly Response GMeet

  2. Determine if ACIS is Safe
    3. Confirm that ACIS is safe via our realtime pages:
    1. SIM is at the HRC-S position -99616 (i.e. ACIS is stowed under cover).
      It should nominally be at -99616 but as long as it's less than -25000, ACIS is safe.

    2. DPA input currents indicate that all but 3 FEPs have been powered down:
      3. 1DPICACU between 0.71 - 0.77 A,
      1DPICBCU between 0.86 - 0.95 A
      1CBAT between -73 to -55
      1DEICACU between ~0.2 to 1.5

    3. DEA time-averaged power is approximately less than 30 W (i.e. the DEA video boards have been powered down).

    4. Status bits indicate that a science run is not active, the last boot was a normal boot and the flight SW is still running:
      5. 1STAT1ST = 1(green) science not active
      1STAT2ST = 1(green) normal boot
      1STAT0ST = 0 or 1 toggles every 64s to indicate SW is running
      Monitor the 1STAT0ST bits for at least 64 seconds to observe at least one toggle transition

    If ACIS is safe:

    Report, on the telecon that ACIS is safe.

    If ACIS is NOT SAFE :

    Report on the telecon that ACIS is NOT safe:

    Various SOPs will be run. Monitor to be sure ACIS is safed.

  3. Shutdown Time and Type
    4. If this is an autonomous shutdown: obtain the type and time of shutdown. Initially there is a flurry of activity on the GMeet telecon.
    Listen for a report of the type and exact time of the shutdown.
    If no one has requested the time of shutdown, wait for a lull in the action and request the time of shutdown at their convenience.
    Also determine if the shutdown is an SCS-107-only or Full Stop (where both the science and vehicle leads are stopped).

  4. Run history_files.pl
    5. Instructions for this can be found on the ACIS Load Review Web page: ACIS Load Review Web page
    Use the time obtained in the previous step in your history-files.pl command line. The command line looks like this:

    $ history_files.pl -s107 {time} {status-array}

    When you run history-files and the situation requires that you supply Quaternions, check the NLET file:

    /data/acis/LoadReviews/NonLoadTrackedEvents.txt

    ....by scrolling to the bottom of the file and compare the calculated pitch to the pitch reported on the telecon.

  5. Is this a Radiation Shutdown?
    6. If the shutdown is due to high Solar radiation, follow the steps listed on the ACIS Response to Radiation Shutdown web page.

  6. SCS-107 or Full Stop Shutdown?
    7. If the shutdown is an SCS-107-only shutdown the maneuver load will continue to execute and ACIS should be fine from a thermal standpoint.

    If the shutdown is a Full Stop, the spacecraft will eventually be moved to a tail sun orientation.

    For that situation, you can refer to these 1DPAMZT, 1DEAMZT and FP TEMP plots which will show the long term (the science portion of one full orbit)
    settling temperatures of these MSID's after a safing action where the pitch is between 130 and 160, HRC-S is in the focal plane, 3 FEPS are on,
    ACIS is not clocking, video boards are off and at a nominal roll.
    All other pitches are fine.

  7. Obtain some Format 2 data
    8. As the shutdown continues, if we aren't in Format 2, you might want to collect some DEA Housekeeping data.
    If so, when things are not as hectic, ask for some Format 2 time to read some ACIS DEA Housekeeping data.

  8. Consider executing a Long Term ECS Measurement (LTECS)

    9. If the shutdown seems to be prolonged enough to allow it and the team is not busy struggling with spacecraft issues, you can consider running a long term ECS measurement.
    Instructions on how to do that can be found at ACIS ECS RTS CAPs - HOW-TO

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