STS-67 Day 13 Highlights
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- On Wednesday, March 15, 1995 at 6 a.m. CST, STS-67 Payload Status Report # 27
reports: (13/5:22 MET) STS-67 Pilot William Gregory placed
the orbiter in the proper attitudes for Mission Specialist John
Grunsfeld to align the Instrument Pointing System (IPS) to selected
areas in the sky. Payload Specialist Ronald Parise then aligned the
Wisconsin Ultraviolet Photo-Polarimeter (WUPPE), the Hopkins
Ultraviolet Telescope (HUT) and the Ultraviolet Imaging Telescope
(UIT), allowing them to lock on to four targets in the Large
Magellanic Cloud (LMC).
- Guest Investigator Dr. Geoffrey Clayton of the University of
Colorado in Boulder will use WUPPE and HUT information about
ultraviolet polarization in the LMC, comparing these data to what
scientists already know about the nature of dust particles in the
interstellar medium of our own galaxy. Using selected stars of the
LMC to back light the dust and gas, Clayton can examine the behavior
of the many dust grains found there. In contrast, a bright, blue-hot
supergiant star, Sanduleak 67-90, was the target of one of last
night's four LMC observations to let astronomers study the dynamics of
ultraviolet emissions in an area where there was not a substantial
amount of stellar dust. UIT takes images of all fields in the
Magellanic Clouds, and obtained excellent data in parallel with the
observations being made by HUT and WUPPE.
- In other observations over night, HUT scientists got another chance
to learn more about a halo of ultra-hot gases they believe surrounds
our Milky Way galaxy. HUT was pointed at the brightest quasar in the
sky, 3C273, which is approximately two billion light years away. As
ultraviolet light from the quasar shines through interstellar space,
it is absorbed by the halo that surrounds our galaxy. Scientists at
the Johns Hopkins University in Baltimore, Md., will analyze these
data in the months following Astro-2, testing theories about whether
the halo actually exists, and if so, how hot the gas is and how far it
- Mission Specialist Wendy Lawrence maneuvered the orbiter into
position, Payload Commander Tammy Jernigan aligned the IPS and Payload
Specialist Sam Durrance pointed HUT to again record ultraviolet
spectrographic data of the "young" supernova remnant, SN 1006. This
supernova remnant, first documented by Chinese astronomers in the year
1006, is giving HUT Guest Investigator Dr. John Raymond an opportunity
to study the physics of shock waves before they hit a substantial
amount of interstellar material (where the gas begins to cool off and
slow down). Traveling at approximately 1,200 miles (2,000 kilometers)
per second, the shock waves from this young supernova remnant are
providing new insights into the characteristics of interstellar medium
surrounding the site of a supernova explosion.
- Parise also pointed HUT at elliptical galaxies called M60 and M89
last night. These galaxies are part of the Virgo cluster, a huge
cluster of galaxies centered some 50 million light years from Earth.
Astronomers have long been interested in these galaxies because of
their very high ultraviolet upturn an excessive output of
ultraviolet light for an old star population. HUT and UIT scientists
are interested in these targets to learn more about what is causing
the excessive amount of ultraviolet light. The theory was that younger
star- formation galaxies produce more ultraviolet emissions than older
star populations. However, observations of galaxies such as M60 and
M89 are leading scientists to believe that some of these old low mass
star populations may be in a more advanced stage of evolution. UIT is
making a two- dimensional map of the ultraviolet upturn across the
face of the M60 galaxy. Near the end of the M89 observation, WUPPE's
dedicated experiment computer experienced a brief software problem.
Durrance recycled power to the computer, which reset the software.
The WUPPE science team has reactivated their telescope from the ground
and resumed operations.
- Durrance and Parise pointed HUT at several other celestial objects
during the night. HUT observed planetary nebula NGC 1360, a cloud of
gas and matter surrounding a star. The nebula glows because the
ultraviolet radiation from the star ionizes the material in the
surrounding cloud, which, in turn, emits energy at a variety of
wavelengths. HUT scientists will study the ultraviolet light from the
nebula and the star to learn more about the material making up the
nebula and the star at its core.
- UIT imaged NGC 752, an open star cluster, searching for hot
accreting binaries, planetary nebulae and X-ray sources. UIT
scientists are particularly interested in probing star clusters such
as this for white dwarfs and other faint, hot stars.
- On Wednesday, March 15, 1995 at 8 a.m. CST, STS-67 MCC Status Report # 26
reports: Mission Specialist Tammy Jernigan, a native of
Chattanooga, talked with a Tennessee radio station along with crew
mate Wendy Lawrence. The discussion centered around the astronomical
observations being conducted throughout the mission as well as
homeowner- type questions posed to Jernigan, making her third flight
aboard the Shuttle. Along with Sam Durrance, the three astronauts
have been choreographing orbiter maneuvers with instrument pointing to
precisely aim the ASTRO observator at the desired celestial targets
throughout the universe.
- Before Lawrence turns in, she will join Oswald and Gregory in the
routine, pre-entry checkout of Endeavour's flight control system,
which includes verifying the health of the moveable surfaces on the
wings and tail used during the atmospheric reentry portion of landing.
One of the Endeavour's three hydraulic systems is required during
portions of the checkout scheduled to begin about 12:30 this
- On Wednesday, March 15, 1995 at 4:30 p.m. CST, STS-67 MCC Status Report # 27
reports: Endeavour's astronauts successfully tested their
ship's flight control systems today in preparation for Friday's
scheduled landing at the Kennedy Space Center. Commander Steve
Oswald, Pilot Bill Gregory and Mission Specialist Wendy Lawrence fired
up one of Endeavour's auxiliary power units to test the Shuttle's
aerosurfaces as part of the routine prelanding tests to insure that
Endeavour is ship-shape for its high-speed return to Earth.
- After a short break in data-gathering to accommodate the flight
control system test, Mission Specialist John Grunsfeld and Payload
Specialist Ron Parise resumed ultraviolet studies of distant celestial
objects with the trio of ASTRO-2 telescopes housed in the Shuttle's
cargo bay. Oswald, Gregory, Grunsfeld and Parise also answered
questions from the Cable News Network as their marathon mission nears
its end. The astronauts will begin to deactivate and stow equipment
Thursday in preparation for their planned homecoming Friday.
- On Wednesday, March 15, 1995 at 6 p.m. CST, STS-67 Payload Status Report # 28
reports:(13/17:22 MET) Hopkins Ultraviolet Telescope (HUT)
Principal Investigator Dr. Arthur Davidsen said, "For all of us, the
on has been like a dream come true. We've observed more
than 100 different HUT targets and had more than 300 pointings with
two days to go, and we're absolutely thrilled."
- "We're really pleased down here," Ultraviolet Imaging Telescope
(UIT) Principal Investigator Ted Stecher told the crew, quipping, "We
never thought we'd run out of film, but now we're a little worried
about it." He said all the team's top priorities have been achieved,
with just a few secondary programs left to complete, and they have
photographed essentially all the objects they had originally planned
- Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE)
Principal Investigator Dr. Arthur Code agreed. "We're delighted with
mission results, too. Reality has exceeded our fondest dreams, and
we've obtained about three times as much data as we did on Astro-1 --
a whole treasure chest of goodies."
- Observations continued to stack up at a steady pace throughout the
day, interrupted only by a planned hour of orbiter flight control
system tests in preparation for Friday's landing.
- All three telescopes took ultraviolet data during a UIT-led
observation of M 87, a spectacular elliptical galaxy in the
constellation Virgo. "We can get information for several of our
favorite scientific programs by viewing M 87," said UIT team member
Dr. Susan Neff. The galaxy is thought to have grown to its large size
by swallowing up smaller neighbors in the Virgo galaxy cluster. A
1994 Hubble Space Telescope observation of M 87 revealed a
spiral-shaped disk of gas swirling at an immense speed in the galaxy's
center, providing the first almost irrefutable evidence that
supermassive black holes do exist in the universe. A fantastic jet of
material, moving at a large fraction of the speed of light, emanates
from the area of the black hole. UIT's wide field of view allows it
to photograph some 12 to 14 Virgo cluster galaxies in the same frame.
UIT team members are studying the stellar populations in M 87 and also
the jet. HUT concentrated on the gas around the black hole to find
out how it is stimulated by radiation from heated matter falling
toward hole. WUPPE made ultraviolet polarization measurements to
determine the structure of the swirling gas.
- The Astro-2 telescopes made the mission's first observation of
Omega Centauri , a giant globular star cluster which is easily visible
in the southern hemisphere to the naked eye. Its brightness is due
both to its relative closeness to Earth (17,000 light years) and its
immense size (150 light years across and containing more than one
million stars). UIT's single five-minute exposure of this star
cluster during Astro-1 was the first ever made in ultraviolet
wavelengths. Even that brief snapshot showed an unusual number of
stars that did not conform to the theoretical pattern of stellar
evolution. Also, since all stars in a globular cluster are formed at
the same time, it should follow that they would have the same chemical
composition, but this is not the case in Omega Centauri. The longer
Astro-2 observation of this globular cluster, along with those of
other clusters throughout the mission, should give scientists more
clues for solving this stellar mystery.
- The telescopes also observed M 92, a much smaller globular cluster,
and UIT made photographs of the galaxies NGC 1512 and NGC 1365 for Dr.
Wendy Freedman's spiral galaxy atlas.
- The majority of WUPPE-led observations today centered on the team's
study of interstellar dust in our Milky Way and in its neighboring
galaxy, the Large Magellanic Cloud. A lower abundance of heavy
elements in the Large Magellanic Cloud causes both the stars and dust
to be different from those in our galaxy, and that dissimilarity is
most apparent in the ultraviolet. Comparison of the two galaxies
could help astronomers define the extent of differences and perhaps
determine the reasons for them.
- The WUPPE team also viewed the star 51 Ophiuchi, for their study of
luminous spinning "Be" stars, whose outer layers show evidence of
being pulled off by their stellar winds. Dr. Regina Schulte-Ladbeck
used WUPPE to observe HD 51285, a star between the Earth and one of
the Wolf-Rayet stars she has been studying. She will use results to
subtract polarization in the interstellar medium from her Wolf-Rayet
- The HUT team revisited their prime calibration target, the white
dwarf star HZ 43, for end-of-mission instrument verification. They
also viewed another portion of the Vela supernova remnant and made the
mission's first observation of LSV 46-21, a white dwarf at the center
of a planetary nebula. The active galaxy NGC 4151 was observed for
the sixth time during this flight.
- Another study of Jupiter, along with its moons Io and Callisto,
begins this evening's observations. Tonight's viewing choices are
fairly evenly divided among the three ultraviolet telescope teams,
with targets again ranging from tiny white dwarf stars to surveys of
large sky areas.
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