Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/ops/swat/safing/09166/2009_06_15.status Дата изменения: Tue Jun 16 01:06:30 2009 Дата индексирования: Sun Mar 2 03:08:03 2014 Кодировка: Поисковые слова: accretion disk

Date: Mon, 15 Jun 2009 16:59:41 -0400 (EDT)
From: Kenneth Sembach
Subject: HST Status 5:00 PM June 15, 2009




Good Afternoon Everyone,

Early this morning, Hubble's new Science Instrument Control
and Data Handling (SI C&DH) unit stopped communicating
properly with HST's main spacecraft computer (the "HST 486").
The 486 computer recognized this lack of communication and
initiated a macro to put the science instruments into safe
mode. This anomaly is similar in some respects to the
one encountered with the old SI C&DH in September, which
was the result of a hardware failure in the old SI C&DH and
which led to the decision to replace that unit during SM4.

However, today's anomaly was different in several
important ways. In today's case, the safing macro seems
not to have invoked the desired response - safing of the
instruments - as evidenced by the lack of a current
decrease after the macro executed. (If the instruments
safed, we would have expected them to be drawing less
current.) As a result of the anomaly there was little
insight into the condition of either the SI C&DH or the
instruments. A decision was made this afternoon to power
cycle the SI C&DH, the next logical step on the road
to recovery. That power cycling produced the intended
result of restoring the SI C&DH to operation, a second
and very important difference from the September event
with the old SI C&DH. The instruments have now been safed
gracefully, and the SI C&DH is being monitored.

The successful recovery of the SI C&DH this afternoon
is good news indeed. Analysis of the day's events
continues. I'll provide further updates as warranted.

Hubble cheers,
Ken