Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/ops/swat/safing/08254/hst_update.txt Дата изменения: Tue Sep 16 13:59:17 2008 Дата индексирования: Sun Mar 2 02:28:09 2014 Кодировка: Поисковые слова: storm

Date: Mon, 15 Sep 2008 15:53:16 -0400
From: Rodger Doxsey
Subject: HST status and SM4 launch date

Colleagues,

We have had a busy few days lately, so I thought I would pass on
some info about both HST and the SM4 launch date.

HST status:

Last week there was an installation of the NSSC-I flight software,
in support of SM4. The NSSC-I knows about the various instruments in
the telescope, and particularly watches the telemetry to see that
they are working properly. The NSSC-I is the first, and most
commonly used, line of defense when something goes wrong with an
Instrument. It will automatically suspend or safe an instrument if
it sees telemetry values out of limits. The software installation
last week put in place a version of the NSSC-I software that "knows"
about all the current instruments, plus the WFC3 and COS. It was
installed to be ready for SM4. The NSSC-I will be instructed, as the
servicing proceeds, which instruments are currently in the telescope
and should be checked for safety items.

The software installation resulted in two unrelated problems, one
for the WFPC2 operations and one for the NICMOS/NCS operations. In
the case of the WFPC2, there was a procedural error and a flight
software table error that resulted in the WFPC2 being put into
safemode. The flight software code has been double checked, and
there was only the one error, the one that affected WFPC2
operations. That will be corrected, as will the procedural error,
and the WFPC2 will be recovered from safemode on Tuesday.

In order to change out the flight software it was necessary to shut
down the NCS, the NICMOS Cyrocooler System. This is the system that
was installed in SM3B and maintains the NICMOS detectors at the low
temperatures they need to operate properly. When the cooler was
restarted it failed some of the on-board checks for its turbo
machinery and automatically shut down. A second attempt to restart
it was made yesterday. That attempt also failed, but in a somewhat
different way. A third attempt will be made this afternoon. The
problems we are encountering with restarting the NCS look like they
are related to very small amounts of contamination, likely water, in
the cooling loop. This contamination is believed to have been frozen
as ice in a benign place in the system over the last 6 years. When
the NCS is shut down, various parts warm up at different rates. It
is believed that some of the contamination has moved around as a
result of the partial warming of the system, and is now interfering
with the readings of circulator speed, and inducing some additional
drag as well. At the current time we believe there has been no
permanent damage to the system. If the attempt to restart the NCS
this afternoon fails, we likely will allow it to warm up to room
temperature before restarting. It is believed that this should solve
the problem, but means the NCS and NICMOS would be off line until
after SM4 (we need to shut the NCS down during SM4 as well, to save
power).


SM4 launch date:

As you know, hurricane Ike hit the Galveston/Houston areas quite
hard. Johnson Space Center is right between Galveston and Houston
and also took the brunt of the storm. At this point, JSC is expected
to be closed this entire week. From what we have heard, there was no
physical damage to the JSC facilities that directly support the
Shuttle. However, the storm has clearly affected the work force at
JSC, all of whom live in the area that was struck by Ike. The JSC
web-site indicates that it is too early to tell how Ike might impact
the future Shuttle schedules, including our flight, which is the next
one scheduled. So, officially the launch date is still October 10,
but it may well get adjusted. As soon as we hear anything about
that, we will pass the info along.

Rodger