Fwd: Update on the ACS Suspend

From: Marc Postman (mpostman@comcast.net)
Date: Thu Jun 22 2006 - 15:16:23 PDT

  • Next message: Chris Lidman: "VLT time"

    Here is the latest info on ACS...

    Begin forwarded message:

    > Since the last update, a number of theories regarding the cause for
    > the suspension of ACS have been ruled out or at least rendered
    > highly unlikely. The leading theory for the suspension appears to
    > be a failure of the +15 Volt power converter, which supplies both
    > the HRC and WFC CCD Electronics Boxes (CEBs). However, a failure
    > within the CEBs has not been completely ruled out as of this time.
    > Further tests with ACS and with ground equipment are being
    > performed now and are scheduled to continue for the next days.
    >
    > Preparatory work for a potential switch to the redundant
    > electronics of ACS (ACS Side 2) has started. A detailed timeline
    > and recovery procedure for this switch was developed and initially
    > tested last year. Assuming that the cause of the failure can be
    > identified with reasonable certainty by the middle of next week,
    > the nominal schedule foresees a Flight Readiness Review next
    > Thursday, 29 June, with the switch to Side 2 being part of the SMS
    > starting on 2 July. Should the tests yield tangible results
    > earlier, this schedule may even be advanced somewhat.
    >
    > Since this morning, an SMS without any ACS commanding is executing.
    > Likewise, the SMS for next week does not contain any ACS observing,
    > but has been filled to the extent possible with science
    > observations using the remaining instruments.
    >
    > We will provide further updates as information becomes available.
    >
    > Helmut



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