Astro-2 Public Affairs Status Report #15	
6:00 a.m. CST (7/5:22 MET), March 9, 1995	
Spacelab Mission Operations Control	
Marshall Space Flight Center	
Huntsville, Ala.


   STS-67 crew members spent a busy seventh night in space, pointing
three unique ultraviolet telescopes toward celestial objects for the
second Astronomy Observatory (Astro-2) mission.

   Mission Specialist Wendy Lawrence maneuvered the Space Shuttle
Endeavour into a position where Payload Commander Tammy Jernigan could
align the Ultraviolet Imaging Telescope (UIT) with M33, a nearby
spiral galaxy in the constellation Triangulum.  This galaxy, also
called the Pinwheel galaxy, is approximately 2.4 million light years
away, but is bright enough to be seen with binoculars at night.  "We
are looking at this neighboring spiral galaxy during Astro-2 to learn
more about what goes on in that galaxy and compare this information to
what we already know about the Milky Way," said Mission Scientist
Dr. John Horack.

   The UIT instrument is a combination of a telescope, image
intensifiers and cameras.  Data from this instrument are recorded
directly onto very sensitive astronomical film, which will be
processed and analyzed after Endeavour returns to Earth.  UIT also
helps astronomers identify thousands of individual hot stars in other
galaxies that may later be examined by the Hubble Space Telescope.

   Payload Specialist Ron Parise aligned the three onboard telescopes,
allowing UIT to make deep, wide-field images of a globular cluster of
stars known as NGC 362.  Globular clusters, massive spherical
concentrations of extremely old stars, are generally located outside
the plane of the galaxy and form a halo around the center.  These old
stars (possibly 10 billion years old) provide astronomers with
knowledge about the latter part of stellar evolution.

   Another type of star cluster, an open cluster, was imaged by UIT
last night.  An open star cluster is moderate in size, containing from
only a few dozen to a few hundred stars.  The age of the stars in an
open cluster can range from very young stars to older stars.  UIT
scientists are particularly interested in searching the heavens for
white dwarfs and other faint, hot stars to be used as backlighting to
study interstellar medium Ð the gas and dust between stars.  These
data will also provide highly accurate distance measurements and add
to astronomers' understanding of the chemical evolution of galaxies.

   The Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE)
telescope examined a supergiant, one of the largest, most radiant
stars in the sky.  The largest of these massive stars may measure
1,000 times the radius of the sun, but their enormous size is coupled
with their voracious consumption of nuclear fuel, leading supergiant
stars through speedy evolutions and spectacular deaths in the form of
stellar explosions called supernovae.
	
   The three Astro-2 ultraviolet telescopes were pointed at Jupiter's
moon Io, the most volcanically active body in our solar system.  A
recent volcanic eruption on that moon, just before the Astro-2 mission
began, ejected material onto Io's surface and into Io's atmosphere.
Dr. Paul Feldman, co-investigator for the Hopkins Ultraviolet
Telescope (HUT) observed Io last night to detect possible changes in
the number of sulfur and oxygen ions in Io's atmosphere.
	
   As Io orbits Jupiter once every 42 hours, some of this material is
left behind, forming a donut-shaped torus of sulfur and oxygen plasma
around Io's orbit.  This plasma torus will be observed in a separate
Jupiter pointing during Astro-2.
	
   Parise next pointed HUT at a starburst galaxy.  While most galaxies
appear to have developed their stars billions of years ago, some are
forming new stars at an enormous rate in a process known as a
starburst.  The massive, hot young stars emit strong ultraviolet
light, detectable by the telescopes onboard the Space Shuttle
Endeavour.

   Parise also aligned HUT to observe WX Hydri, a dwarf nova in a
binary star system.  The dwarf nova for this observation, WX Hydri,
undergoes irregularly spaced outbursts, approximately once every 10
days.  Scientists for HUT and WUPPE are interested in a process
associated with binary stars called accretion, where matter is
transferred from the smaller star to the larger star, causing the
interstellar gas to heat up and create bright ultraviolet emissions.

   HUT observed a very hot, massive blue star for Guest Investigator
Dr.  Nolan Walborn.  The star known as NGC 346 #3 is located in a
cluster of stars in the Small Magellanic Cloud. This star is being
studied because of its strong stellar winds.  Data from this Astro-2
observation will be combined with observations made by the Hubble
Space Telescope and the European Southern Observatory's CASPEC
satellite, giving scientists a better understanding of this star,
which has a relatively brief life Ð from 3 to 6 million years.
Several other stars in the NG 346 cluster will also be observed during
Astro-2.

   During the next 12 hours, the crew of Endeavour will aim the
Astro-2 telescopes toward quasars, supernova remnants, white dwarfs,
and cataclysmic variables.  HUT scientists will also use their
telescope to do a joint observation of Jupiter with the Hubble Space
Telescope.

   To follow the mission in progress, visit Astro-2's home page on the
Internet World Wide Web: URL "http://astro-2.msfc.nasa.gov"