STS-67 Day 10 Highlights
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- On Sunday, March 12, 1995 at 9:30 a.m. CST, STS-67 MCC Status Report # 20
reports: Tammy Jernigan, Sam Durrance and Wendy Lawrence assisted
ground controllers in Alabama with fine-pointing of the three
telescopes. For the first time, an observation was made of the Moon
as the Shuttle passed south of Hawaii on the 161st orbit of the
mission in an effort to gather ultraviolet data to help determine the
Moon's origin. Several additional observations of moons and asteroids
will be made throughout the mission.
- On Sunday, March 12, 1995 at 6 a.m. CST, STS-67 Payload Status Report # 21
reports: (10/5:22 MET) Mission Specialist Wendy Lawrence
maneuvered the orbiter into the required position, while Payload
Commander Tammy Jernigan aligned the Instrument Pointing System (IPS)
at the most difficult-to-acquire Astro-2 target, our moon. Payload
Specialist Sam Durrance coordinated with science teams at Marshall
Space Flight Center in Huntsville, Ala., to accurately point the
Ultraviolet Imaging Telescope (UIT) at the moon. "The entire moon has
never been imaged in the ultraviolet wavelengths, and we're looking
forward to seeing these data," said UIT Guest Investigator Dr. Chan Na
of Southwest Research Institute. No similar data have been obtained
from either previous Shuttle missions, the Apollo program or
Clementine, and there are no operating or planned spacecraft capable
of imaging the whole moon at far ultraviolet wavelengths.
- UIT Guest Investigator Dr. Randy Gladstone, also of Southwest
Research Institute, is using UIT to make far ultraviolet maps in order
to learn more about the surface properties of the moon. "This lunar
observation yielded 12 good, wide-field exposures of the moon," said
Gladstone. The 70mm UIT film will developed and analyzed when
Endeavour returns to Earth. UIT data gathered during Astro-2 will be
used to test the hypothesis that the far ultraviolet surface
brightness of an object without an atmosphere is a good indicator of
the length of time that the surface has been exposed to space. These
data will also help scientists understand future ultraviolet images of
asteroids and other planetary satellites.
- The Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE)
telescope observed the moon along with UIT last night to determine how
well the WUPPE instrument could detect such features as dark seas or
bright craters on the moon. Video from the WUPPE guide camera showed
the instrument could clearly distinguish these lunar surface features.
WUPPE scientists will now decide what observational goals they will
set for the next lunar observation, later in the mission.
- Durrance also pointed the WUPPE telescope to a cool, giant star
known as Alpha Orionis. This star, which pulsates about every five
years, is approximately 14,000 times as radiant as our sun. WUPPE
Principal Investigator Dr. Arthur Code will analyze the data from this
Astro-2 observation to learn more about what effect these pulsations
have on the envelope of gas and dust surrounding Alpha Orionis.
- Pilot William Gregory moved Endeavour into position, Mission
Specialist John Grunsfeld aligned the IPS and Payload Specialist
Ronald Parise again pointed the Hopkins Ultraviolet Telescope (HUT) at
the quasar known as 1700+64. This quasar is the most distant object
the HUT team is observing during Astro-2. HUT Principal Investigator
Dr. Arthur Davidsen, of Johns Hopkins University, is using the quasar
to provide background lighting in a search for helium in the
intergalactic medium (the gas between galaxies). Helium is thought to
be left over from the "Big Bang," a primordial fireball that many
astronomers believe marked the birth of the universe about 10 to 20
billion years ago.
- The HUT telescope also observed a portion of the Cygnus Loop, a
"middle-aged" supernova remnant, over night. Supernova remnants are
visible evidence of the final cycle of stellar evolution and important
sources of information for astronomers. The Cygnus Loop is of
particular interest because it reveals details about the structure and
velocity of shock waves from the explosion of a dying star) as they
travel through the interstellar medium. HUT's spectrographic data
will help scientists determine temperatures, densities and chemical
compositions of the gases located in the Cygnus Loop.
- HUT team members say their recent observations of the Vela
supernova remnant will allow scientists, for the first time, to
measure the same supernova remnant shockwave from two angles. The
Vela observations seem to show the same filament of expanding gas from
the stellar explosion both edge on and face on. "If we can compare
this filament in two positions, and verify that the models work for
this object, we can generalize that and compare it to other data we've
taken on the Cygnus Loop, the Vela supernova remnant and with other
telescopes," said HUT Co-investigator Dr. Bill Blair. If successful,
the comparison should give researchers a much better understanding of
- Parise pointed WUPPE and HUT at a hot, massive star called 48
Librae, located in the constellation Libra. This star spins rapidly
and has an outer layer that shows evidence of being peeled off by
stellar winds. Previous observations of this star have suggested that
its stellar winds are strongest near the star's equator because of its
rapid rotation. WUPPE scientists are examining the polarization of
this star's light to learn more about the scattering by electrons in
the disk surrounding it. HUT scientists are trying to determine an
accurate temperature for this star, search for stellar winds, and
study absorption in the gas and dust between this star and nearby
- Jernigan and Durrance aligned WUPPE and HUT to look at a supergiant
star, P Cygni. This star, which increases in brightness like a nova,
has remained just visible to the naked eye for more than 100 years.
Scientists believe it is not a true nova, rather a variable star
surrounded by an expanding gaseous shell. WUPPE scientists are
interested in P Cygni because it is ejecting mass at a colossal rate.
As P Cygni scatters light, it produces a pronounced polarization which
differs from theoretical models. Data from these Astro-2 observations
will test refined theories and offer greater insight into the
mysterious variability of P Cygni.
- Throughout the next 12 hours, HUT, WUPPE and UIT will be used
to observe the planet Mars, look at young stellar populations in
galaxies, examine supernova remnants and study a reflection nebula in
a dark cloud.
- On Sunday, March 12, 1995 at 5 p.m. CST, STS-67 MCC Status Report # 21
reports: Both Grunsfeld and Parise enjoyed a few hours off to relax
before heading into the final days of the mission, trading places on
the aft flight deck to operate the Instrument Pointing System and the
telescopes while the other took a break from research duties. Gregory
used Endeavour's ham radio gear to talk to students at the J.J. Fray
Elementary School in Rustburg, Virginia and the crew continued to
respond to questions about their mission and spaceflight in general
placed on the Internet and faxed up to the Shuttle by flight
- On Sunday, March 12, 1995 at 6 p.m. CST, STS-67 Payload Status Report # 22
reports: (10/17:22 MET) The Wisconsin Ultraviolet Photo-Polarimeter Experiment
(WUPPE) team selected Nova Circinus 1995 for observation this morning. This
is the third "new" nova -- a binary star system whose first outburst was
observed very recently -- to be studied by the Astro-2 telescopes.
"Though all three novae went into outburst since the first of the year,
each is at a different stage in its history," said WUPPE Principal
Investigator Dr. Arthur Code. "By comparing their polarization, we hope to
determine whether gas from novae outbursts is expelled in a spherical shape
and then becomes more asymmetrical, and if so, how quickly the asymmetry
develops." Light is polarized when it encounters an asymmetrically
shaped object, such as a flattened gas disk, which causes the light to
vibrate in preferred directions.
- "Every day brings new surprises," said HUT Co-investigator Dr. Bill
Blair, describing the success today of two supernova remnant
observations he admits were long-shots. HUT led a study of the
supernova remnant Puppis A, the third supernova remnant Astro-2 has
observed in our Milky Way galaxy. HUT and WUPPE examined a filament
of gas in the remnant's eastern region, apparently an interaction
between an interstellar cloud and the blast wave speeding from the
supernova explosion. "The International Ultraviolet Explorer barely
detected this remnant, so we didn't know what to expect," said Blair.
"We thought dust in the interstellar medium might block its
ultraviolet radiation, but we got a very nice spectrum which showed
strong nitrogen emissions." Blair said it is possible the nitrogen
could have been thrown out by the massive star thousands of years
before it exploded as a supernova, and now the shock wave from the
blast is catching up with nitrogen expelled from the star.
- Supernova 1006, whose explosion in A.D. 1006 makes it a relatively
recent supernova, provided another first. "The shock wave from this
supernova is moving very fast, plowing through interstellar space at
about 2,000 kilometers (1,250 miles) per second, as opposed to 150 to
200 kilometers per second in remnants like Puppis A," said Blair. "We
thought its emissions might be too faint for us to observe, but we
felt it was important enough to attempt. This gives us a new range of
velocity that has never been observed before in the ultraviolet."
Blair said the HUT spectrum may show the primary passage of the
supernova blast wave as it first encounters interstellar gas.
Comparison with optical observations could help astronomers understand
the basic physics of supernova shock fronts.
- The Ultraviolet Imaging Telescope team led eight highly successful
observations in a row. UIT captured the mission's first images of the
Whirlpool Galaxy (M 51) for Dr. Wendy Freedman's atlas of spiral
galaxies. The Whirlpool Galaxy is the larger of two interacting
galaxies close enough together to disturb each other through
gravitational force. M 51 is a large spiral galaxy with a mass 100
billion times that of our sun. It is interacting with NGC 5195, a
much less massive galaxy. Astronomers will study UIT photographs to
learn more about the formation of stars in that system, especially in
the bridge of matter that joins the two interacting galaxies.
- UIT also imaged CB_4, a cold cloud of interstellar gas and dust
which is sufficiently dense to obscure starlight from objects behind
it, while it reflects light from objects in front of it. Though this
so-called dark cloud is relatively faint, Astro scientists were able
to obtain measurements to test models of dust in the interstellar
medium during a daylight observation.
- The imaging telescope also photographed a cluster of galaxies known
as the Coma Cluster. UIT is examining the dense cluster, made up
primarily of elliptical galaxies, to obtain simultaneous information
on large samples of galaxies. Astronomers will study the integrated
ultraviolet properties of these large samples to determine constraints
on the physics of cooling flows, as hot gas may condense into stars as
it rains down on a galaxy from the intra-cluster medium. Scientists
also will look for the presence of dark matter, which does not emit
- HUT and WUPPE observed NGC 4874, the central elliptical galaxy in
the Coma Cluster, to determine the ages of its stars. Though
elliptical galaxies have comparatively few young stars, they emit more
ultraviolet radiation than would be expected from a population of old
stars. Astro-1 observations of ellipticals suggest this radiation may
come from aging stars in a previously unknown stage of evolution.
Astro-2 is following up on the mystery.
- UIT photographed the open star cluster NGC 7789, and investigations
into new star formation included observations of elliptical galaxy NGC
185, irregular galaxy NGC 1313 and rapid star formation galaxy NGC
4631. WUPPE led the mission's first observation of the Planet Mars,
and it observed interstellar polarization probe HD 217490 to add to
its ongoing study of the dust scattered throughout our Milky Way.
Dr. Brian Espey got excellent HUT and WUPPE data on the symbiotic star
system RR Telescopii for his study of closely orbiting stars with
radically different temperatures.
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