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From: starrfie@hydro.la.asu.edu (Sumner Starrfield)
Subject: more news from Goddard
Date: Sun, 5 Dec 93 23:24:30 MST
EVA 1 was completed successfully at 6:39 am EST Sunday morning.
The Hubble Space Telescope now has six good gyroscopes and two
new correctly wired fuse plugs, and substantial preparations
have been made in setting up the new solar arrays for installation
on EVA 2 Sunday night. The EVA began one hour and ten minutes
ahead of schedule at 10:45 pm EST, after the astronauts completed
the necessary preparations faster than expected, and lasted 7 hours
54 minutes, making it the second longest EVA in US space program
history and taking two hours longer than planned. There was one
major problem that occurred when the aft shroud doors could not
be closed following the replacement of the two Rate Sensor Units
(RSU's). The exact reason that the doors would not mate properly
is not yet known, it could be due to thermal distortions that
occurred after the doors were opened, or it could have another
cause. The EVA crew left the door ajar and went about the remaining
tasks of the EVA, changing out Electronic Control Units (ECU's) in
bay 10 of the Support Systems Module (SSM) and fuse plugs in bay 4,
followed by the Solar Array Carrier (SAC) preparations. At the end
of the EVA they returned to the recalcitrant doors and were able
to force the doors closed with a tether device similar to a
"come-along" that is often used by truck drivers to lash down
cargo. With the doors pulled together, the bolts could be installed
in the latches and tightned until the latches were closed. A
gyroscope aliveness test was conducted by the STOCC at Goddard
after the RSU's and ECU's were installed and powered up, and the
gyros were confirmed to be functioning properly.
Because of the extra time needed to close the aft shroud door, the
solar arrays were not commanded to roll up at the conclusion of
EVA 1. The solar array retraction was postponed until after the EVA
crew had repressurized the airlock and rejoined the rest of the crew
inside Endeavour. Two hours later, the -V2 solar array was successfully
rolled up by command from the ground, but the kinked bistem of the
+V2 array has thwarted the effort to retract that array. At 10:00 am
EST Sunday morning, NASA management decided that the damaged solar
array will be jettisoned overboard during EVA 2 this evening. This
will be somewhat of a loss to the scientists and engineers who had
hoped to study the array after its return to Earth to learn more
about space environmental effects on spacecraft materials, though
they will still get one array to study. The decision to jettison
the array will require the shuttle to perform an evasive maneuver
to avoid contacting the array after it is released into space.
A note about the HST coordinate system:
Space vehicles are capable of rotating about three orthogonal axes,
on many vehicles these axes are called roll, pitch and yaw, on the
shuttle orbiter they are called the x, y, and z axes. For HST, the
three axes of rotation are called V1, V2, and V3. The V1 axis is the
optical axis of the telescope, the +V1 axis points toward the object
that is being observed. The V2 axis is perpendicular to the V1 axis
and is the axis about which the solar arrays rotate. The damaged
solar array is known as the +V2 array since it is on the +V2 side
of the spacecraft. The V3 axis is perpendicular to the other two
axes, and is the axis in which the High Gain Antennas stick out,
thus the HGA's are identified as the +V3 antenna and the -V3
antenna. The spacecraft normally keeps its +V3 side facing the Sun,
and the -V3 side rarely sees sunlight. The Wide Field and Planetary
Camera and the Fixed Head Star Trackers are on the -V3 side of HST,
and are rarely exposed to sunlight. You will hear many references
to the HST coordinate system during the EVA's, and the coordinate
system can become confusing even to the engineers who work with
Hubble every day, hence each console in the STOCC and in Mission
Control is equipped with a cardboard model of HST with the axes
and the locations of major pieces of equipment properly marked to
insure that everybody uses the correct coordinate system in their
communications.
STS-61 and HST will be visible to observers near 30 degrees north
latitude for the next several mornings, and to observers near 30
degrees south latitude in the evening. If a shuttle pass occurs less
than an hour before your local sunrise time, but before the morning
twilight is too bright, the shuttle will appear as a bright star
moving across the sky.
Possible sighting opportunites for selected cities,
Monday 12-06
city time elevation azimuth
Atlanta,GA 6:11am EST 24 198 (southwest sky)
Miami, FL 6:13am EST 59 180 (directly south)
Pensacola,Fl 5:11am CST 40 182 (directly south)
Houston, TX 6:50am CST 24 220 (southwest sky)
Albuquerque,NM 5:47am MST 18 211 (southwest sky)
Honolulu, HI 5:01am HST 67 21 (northeast sky)
(assuming 16:01 UTC= 5:01 Hawaii time)
Tuesday 12-07
city time elevation azimuth
Miami, FL 6:19am EST 40 192 (directly south)
Pensacola,Fl 5:17am CST 29 189 (directly south)
Houston, TX 6:56am CST 14 217 (southwest sky)
Albuquerque,NM 5:53am MST 14 210 (southwest sky)
Honolulu, HI 5:07am HST 88 317 (directly overhead)
(assuming 16:07 UTC= 5:07 Hawaii time)
Note for European readers:
>Subject: HST coverage in Europe
Just to confirm that C-Span is indeed covering the mission,
C-span is transmitted during the morning and midday hours
(European time) on the 'Deutsche Welle', Eutelsat 2-F1
13 degrees east, frequency 11163 Vertical (PAL, with audio at 6.60 Mhz)
The two Reuters newsfeeds on Intelsat (21.5 west) were transmitting
testcards only (in NTSC and in PAL), despite persistent rumours that
they would be carrying the HST mission. This was when there was an EVA
going on about 0900 Central European time.
Thanks to Michael Meerman LA/PA3BHF for this information
Dan Schultz
Space Telescope Operations Control Center
Goddard Space Flight Center
Greenbelt, Maryland
E mail: n8fgv@amsat.org
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