Astro-2 Public Affairs Status Report #11
6:00 a.m. CST (5/5:22 MET), March 7, 1995
Spacelab Mission Operations Control
Marshall Space Flight Center
Huntsville, Ala.


   Crew members for the second Astro Observatory (Astro-2) mission
spent a busy fifth night in space, working with three unique
ultraviolet telescopes to help scientists on Earth learn more about
the universe.  Pilot William Gregory and Mission Specialist Wendy
Lawrence maneuvered the Space Shuttle Endeavour into different orbital
positions as Payload Commander Tammy Jernigan, Mission Specialist John
Grunsfeld, and Payload Specialists Ronald Parise and Sam Durrance
aligned the telescopes nestled in Endeavour's payload bay.

   From the Marshall Space Flight Center in Huntsville, Ala., the
science teams for the Hopkins Ultraviolet Telescope (HUT), Ultraviolet
Imaging Telescope (UIT) and the Wisconsin Ultraviolet
Photo-Polarimeter Experiment (WUPPE) watched video from the HUT target
acquisition camera onboard the Shuttle while they calibrated their
instruments.  During this calibration period, in which HUT was pointed
at a hot dwarf star in the constellation Auriga, scientists were able
to check the data from their telescopes against previous observations.

   Three types of galaxies were observed by the Astro-2 telescopes
overnight to help scientists understand more about the formation of
stars in a galaxy system.  UIT used both of its onboard cameras to
make images of these galaxies in both the long and short wavelength
ranges.

   A prime target for UIT was a globular cluster in the constellation
Carina.  This cluster is a massive spherical concentration of stars
containing up to several hundred thousand stars.  This group of stars,
which is extremely old, provides astronomers with information about
the latter part of the evolution of stars.

   HUT and WUPPE observed a massive blue star called Psi Persei Ð a
luminous star that spins rapidly and has outer layers that show
evidence of being peeled off by their stellar winds.  Previous
observations have suggested that these gas-laden winds are strongest
near the equator of these rapidly spinning stars.  Psi Persei has an
unusual ultraviolet spectrum that may be caused by a shell of gas
around the star, possibly the remains of the layer that has been
peeled off the star.  Scientists hope to accurately determine this
type of star's temperature (in order to analyze its atmospheric
emission), search for stellar winds and study absorption in the
interstellar medium, gas and dust between these stars.

   HUT and WUPPE also used a bright star much like a flashlight to
illuminate the gas and dust between stars.  This type of observation
will help scientists understand more about the chemical composition
and physical nature of the dust and gas between stars in our Milky Way
galaxy.  During the first Astro mission, astronomers learned that some
parts of our galaxy seem to have dust grains that resemble tiny hockey
pucks, while other parts seem to have a mixture of several sizes,
shapes and kinds of dust grains.  During Astro- 2, WUPPE Principal
Investigator Dr. Arthur Code hopes to determine whether different
conditions in some parts of the galaxy affect the formation of these
dust grains.

   The science teams for HUT, UIT and WUPPE observed video from the
HUT target acquisition camera as their instruments measured a
supernova remnant known as Cygnus Loop.  This supernova remnant, in
the constellation Cygnus, the Swan, is from a star that exploded many
years ago.  Both cameras of the UIT imaged the supernova remnant in
both the short ultraviolet and long ultraviolet ranges.  Guest
Investigator Dr. John Raymond is using HUT to obtain information about
shock waves Ð the physics of collisionless shocks, the destruction
of grains in shocked gas, instabilities behind radiative shocks and
shock wave parameters.

   The Astro-2 ultraviolet telescopes also observed a Wolf-Rayet star,
thought to represent one of the final phases in the evolution of
massive O and B stars, which have between 100,000 and 1,000,000 times
the radiance of the sun, with temperatures up to 100 times greater.
One of the most unusual features of this type of star is that it has
almost no dark, or absorption, lines in its spectrum, only bright,
broad emission lines.

   The three Astro-2 ultraviolet telescopes also gathered information
about spiral galaxies during the night.  Guest Investigator Dr. Wendy
Freedman is using the UIT to image several large, face-on (top or
bottom view) galaxies in the far- and near-ultraviolet spectrum.
Freedman will combine UIT images gathered on both the Astro-1 and
Astro-2 missions to create a digital atlas of spiral galaxies.  Data
gathered about galaxies will also be used to study the similarities
between the types of galaxies viewed by the Hubble Space Telescope in
the visible and ultraviolet spectrums.

   During the next 12 hours, the Astro-2 crew members will help
scientists on Earth gather data on another Wolf-Rayet star, the
interstellar medium, a white dwarf, galaxies with extremely bright and
compact nuclei, another supernova remnant and a galaxy known for its
rapid star formations.

   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"