Astro-2 Public Affairs Status Report #6 6:00 p.m. CST (2/17:22 MET), March 4, 1995 Spacelab Mission Operations Control Marshall Space Flight Center Huntsville, Ala. During their third day in orbit, the Astro-2 telescopes viewed celestial objects from our own Solar System to the very edge of the universe. The Hopkins Ultraviolet Telescope (HUT) team took the first step toward achieving one of their primary goals for the mission -- detecting the tenuous gas believed to pervade the space between galaxies. The team successfully worked out procedures for observing a quasar, billions of light years from Earth, which they will use in later observations as a source of illumination to view the gas in front of it. "This is the most difficult, but the most exciting, science program of the mission to me," said HUT Principal Investigator Dr. Arthur Davidsen. Existence of the gas is the logical consequence of the "Big Bang," the primordial fireball which marked the beginning of the universe, but it has never been thoroughly observed. "The hydrogen and helium created in the first minutes after the Big Bang ultimately condensed into stars and galaxies, but we want to see the original material before it condensed," Davidsen said. Viewing light from the quasar, one of oldest and most distant objects in the universe, will allow astronomers to effectively look back in time. HUT team member Dr. Paul Feldman was equally excited about an observation much closer to home, when all three Astro telescopes observed Jupiter's moon Io during a volcanic eruption. Ground-based astronomers at NASA's Infrared Telescope Facility in Hawaii sent out a notice Thursday that they had detected a major eruption in progress. "I was excited when I first saw the news, and even more excited with the high-quality spectral data we got today," said Feldman. In addition to being volcanically active, Io is one of the few moons in the Solar System with an atmosphere. Feldman will compare today's observations with those made later in the mission to see whether the moon's atmosphere is maintained by continuous volcanic activity or by evaporation of ices on its surface. He and Astro-2 Payload Specialist Sam Durrance share the Jovian system as their primary subject of astronomical study. The Ultraviolet Imaging Telescope (UIT) obtained pictures of spiral galaxy M83, which will be used in an atlas of face-on spiral galaxies being assembled by Guest Investigator Dr. Wendy Freedman of the Carnegie Institution in Washington. The completed atlas, to include images made by UIT Principal Investigator Ted Stecher on both Astro flights, will be available to astronomers at no cost through a NASA on-line database. Freedman will use the ultraviolet images of nearby galaxies to help classify the shapes of distant galaxies photographed in visible light by the Hubble Space Telescope. The light actually left the distant galaxies as ultraviolet, but it was stretched into visible wavelengths by the expansion of the universe. Freedman is science lead for the Hubble Space Telescope Key Project on the Extragalactic Distance Scale, whose work was featured last week in "Time" magazine. UIT also took images of a closely knit assembly of stars called a globular cluster. Located 14,000 light years away, halfway across our Milky Way Galaxy, the apparent size of the cluster is more than two-thirds that of Earth's full moon. By imaging globular clusters in ultraviolet wavelengths, astronomers can pick out hot objects, which are burning helium, from the clutter of cool stars in the cluster, which are mostly burning hydrogen. The Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE) obtained the first observation of the illuminating star in reflection nebula NCG 7023, to study how stars are created from nebulous clouds of gas and dust. A young star at the nebula's core was formed from material in the cloud, representing the later stage of the "galactic recycling" process. Astronomers know the nebula is highly polarized in visible light. By finding out whether the polarization continues in the ultraviolet, they may be able to determine the size and composition of the dust particles that make up the nebula. Changes in polarization also may help astronomers determine where in the nebula the dust grains were formed. The WUPPE telescope also obtained a spectrum from a recently- discovered nova known as Nova Aquilae. An outburst, or sudden increase in brightness, was first observed in this system of two stars orbiting one another about three weeks ago by amateur astronomers in Japan. This was the first ultraviolet observation of this particular nova, according to WUPPE team member Joni Johnson, and it showed an obvious spectral signature of the gas ejected by the nova explosion. Payload Specialist Sam Durrance noted that the crew is "beginning to get in the groove," as they gain efficiency setting up observations. As originally planned, experiment teams are instructing crew members to use either manual or automatic acquisition procedures, depending on characteristics of the target. "Manual pointing worked so well on Astro-1 that we developed an improved version to use as one of the standard acquisition procedures on Astro 2," said Assistant Mission Manager Stuart Clifton. The Astro 2 team chooses the method they think will work best for each observation, since manual pointing works better for some targets than an automatic target acquisition. "The Instrument Pointing System is working well, and the HUT and WUPPE teams report good stability for their observations," Clifton continued. "We're continuing to work with the Image Motion Compensation System to improve pointing stability for UIT imaging." 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"