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From: starrfie@hydro.la.asu.edu (Sumner Starrfield)
Subject: Now It's Our Turn (fwd)
Date: Fri, 10 Dec 93 8:02:30 MST
Forwarded message:
>From wms@stsci.edu Fri Dec 10 05:57:38 1993
Date: Fri, 10 Dec 93 08:04:23 EST
From: Robert Williams <wms@stsci.edu>
Message-ID: <vsnet-history1890@hoge.baba.hajime.jp>
To: starrfie@hydro.la.asu.edu
Subject: Now It's Our Turn
SM Report #10 (R. Doxsey/STScI)
7:00 AM December 10 344:12:00
Summary of recent activities:
HST is on it's own again, better than ever. The Endeavour
crew, the JSC staff, and the GSFC staff have performed
magnificently during this mission, which has been one
of the most challenging in recent manned spaceflight
history. I have heard several press conference comments
about how "lucky" the mission has been, but chance is a small
factor compared to the design, preparation, training,
and professional spirit that has gone into this mission.
The final checks on the DF224 were made yesterday with
the successful receipt of complete memory dumps through
a clean telemetry link. The problems we had two days
ago are now clearly all related to the poor communications
link quality.
During the day on Thursday several anomolous telemetry
readings appeared in scattered locations. One of these
was an FOC RIU relay, which suddenly started indicating
that the RIU was off. There was other telemetry available
which proved that this "off" reading was erroneous. There
were similar problems with some electrical power system
telemetry points, some of which are used in safemode tests.
After some analysis it was decided to switch from orbiter
power to HST internal power and then to switch from the
A side of DIU 2 to the B side of DIU 2. When this was done
the erroneous telemetry points cleared up and reported
proper readings. When we switched back to the A side the
erroneous readings returned. We returned to the B side for
deployment. The initial analysis indcates that there may
be two bad electronics cards in DIU 2A.
The time required to analyze this problem and switch sides
in the DIU required a two orbit delay in the deploy of HST.
The HST was grappled by the RMS arm and the latches holding
the HST to the shuttle were released. Claude Nicollier,
operating the RMS arm, then moved the HST first to the
"low hover" position just above the FSS fixture, then to the
"high hover" position well above the payload bay. The STOCC
then went through the final HST preparations for deploy.
The aperture door was then opened and the HST released by
the RMS. The shuttle pilots then carefully maneuvered the
Endeavour safely away from HST. The release went well with
no sign of any Endeavour manuevering jet plumes hitting HST.
The Endeavour and HST are now more than two miles apart,
with the distance continuing to increase.
Shortly after release the HST entered software sunpoint
mode as planned. The PCS (pointing control system) quickly
captured the sun and HST communications were shifted from
the Shuttle link to a direct HSt-TDRSS link. HST is now
in a fairly standard safemode situation, one which we have
recovered from numerous times in the past.
After nine days in the shop, HST is on its own again in
better shape then ever. It's our turn now, to get the
optics aligned, demonstrate the full scientific capability
of the HST, and get lots of spectacular data for the GOs and
GTOs.
Problems/Issues/Changes under consideration:
NONE
Near-term plans:
The HST was released essentially into a +V3 software sunpoint
mode. It will stay in this mode for about 30 hours, during
which various flight software reconfigurations will be done
and data on the power and gyros will be obtained. It gives
the STOCC a quiet period to verify that all systems are working
as planned. A 48 hour "Health and Safety" SMS will begin
saturday afternoon. This will establish down-link contact
through the HGAs and provide opportunities to verify the
pointing orientation with the FHSTs, measure gyro drift
rates and determine if the new Solar Arrays give any jitter
during day/night transitions. The first STScI SMS begins
execution at 4:00 PM local time on Monday afternoon.
This sequence of safemode, followed by H&S SMS, followed
by STScI SMS is similar to normal safemode recoverys, with
24 hours more in the H&S portion.
The SMOV period (Servicing Mission Observatory Verfication)
begins with the start of the first STScI SMS. The first
week or so in this period will be spent verifying that
basic HST capabilities have not been compromised during the
servicing mission. We will calibrate the gyro alignments
and then verify that slews, FHST updates, and guide star
acquisitions still work. Basic functionality tests will
be run on each SI using internal observations. We will
verify (or measure) the alignments between the FGSs and
the SIs and then carry out absolute sensitivity tests with
each of the old SIs. This will demonstrate any degradation
(not expected) during the shuttle phase and will provide
a baseline before COSTAR deployment. After these activities
the initial WFPC-II and COSTAR activations and alignments
will start.
I will continue with these reports for several weeks,
although they may become less frequent than daily as
we get into more routine operations.
Return to the Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
