Astro-2 Public Affairs Status Report #13 6:00 a.m. CST (6/5:22 MET), March 8, 1995 Spacelab Mission Operations Control Marshall Space Flight Center Huntsville, Ala. STS-67 crew members aboard Space Shuttle Endeavour spent their sixth night in orbit, pointing and aligning the three astronomical telescopes of the second Astro Observatory (Astro-2) mission. Although payload controllers at Marshall Space Flight Center in Huntsville, Ala., were briefly evacuated to a safe area during severe weather conditions last night, voice communications with the Shuttle continued from Marshall, allowing Mission Specialist John Grunsfeld to coordinate his activities with science teams on the ground . Pilot William Gregory and Mission Specialist Wendy Lawrence maneuvered the orbiter into positions where Payload Commander Tammy Jernigan, Payload Specialists Sam Durrance and Ronald Parise, and Grunsfeld could point the ultraviolet telescopes at a variety of celestial objects in our universe. Grunsfeld pointed the Astro-2 telescopes at a quasi-stellar object, a prime target for the Hopkins Ultraviolet Telescope (HUT), known as HS1700+64. Principal Investigator Dr. Arthur Davidsen and the HUT science team are searching for the helium left over from the primordial fireball that many scientists believe marked the birth of the universe some 10 to 20 billion years ago. To find the ash remnants of the explosive genesis of the universe, astronomers must use the faint glow of extremely distant objects, such as this quasar, located behind the intergalactic gas Ð similar to using a distant flashlight shining through a hazy mist. HUT was aimed at this Astro-2 target, located many billions of light years away, to help scientists search the gas for evidence that helium is absorbing the quasar's ultraviolet light. Jernigan and Durrance aligned the Wisconsin Ultraviolet Photo- Polarimeter Experiment (WUPPE) telescope to look at two other stars serving as background lights in the study of interstellar polarization Ð the orientation of ultraviolet light waves that travel through the gas and dust between stars. Interstellar polarization studies enable scientists to make allowances for obscuring matter when they study other objects in the universe as well as learn about the obscuring matter itself. The Ultraviolet Imaging Telescope (UIT), WUPPE and HUT observed the dying remains of a star a white dwarf. This small object, which has burned all its nuclear fuel, allowed WUPPE Principal Investigator Dr. Arthur Code to observe the orientation of the ultraviolet light traveling from the white dwarf to determine its geometry and density. UIT imaged the white dwarf and the surrounding night sky to help scientists search for more of these faint, hot stars. Gregory maneuvered Endeavour into position during two separate orbits to allow all three Astro-2 ultraviolet telescopes to observe spiral galaxies. One of these spiral galaxies, known as NGC 2841, contains remnants from Supernovae 1912 and 1957A. The second spiral galaxy, called NGC 2403, is a galaxy containing an old yellow star population in its center region that merges into a disc with widely scattered blue star-formation knots in its spiraling "arms." Guest Investigator Dr. Wendy Freedman will use UIT images of these two galaxies in a digital atlas of spiral galaxies. Two other galaxies were observed by the ultraviolet telescopes nestled in Endeavour's payload bay last night. Guest Investigator Dr. Claus Leitherer used HUT to observe a starburst galaxy and UIT Principal Investigator Theodore Stecher conducted ultraviolet studies of the structure of galaxies during an observation of elliptical galaxy NGC 205. During four separate orbits, Jernigan and Durrance pointed the three ultraviolet telescopes toward a rare type of star known as a Wolf-Rayet star. This type of star is thought to represent one of the last phases in the life cycle of a massive star. Wolf-Rayet stars have powerful, eroding stellar winds. These strong stellar winds have hastened the evolution of the Wolf-Rayet stars, causing what may once have been massive, luminous stars to become less and less massive throughout their life. "We are looking at the way energy coming out of the star interacts with the atmosphere surrounding the star," explained WUPPE Co-Investigator Dr. Chris Anderson. Jernigan and Durrance also brought the Astro-2 telescopes into alignment with two very hot, massive blue stars that emit large amounts of ultraviolet radiation. There is evidence that the outer layers of these two rapidly spinning stars have been peeled off by their stellar winds. From the data gathered during Astro-2, HUT scientists will strive to determine accurate temperatures of these stars to learn more about their surrounding atmosphere, search for stellar winds, and study absorption in the gas and dust between the stars. During the next 12 hours, the STS-67 crew will point the Astro-2 telescopes to the heavens to study electron scattering around very hot, massive blue stars and supergiants, observe metal-rich and metal-poor globular clusters, study young stellar populations in galaxies, and observe the planet Jupiter. 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"