HUT Mission "Absolutely Spectacular" By Emil Venere The space shuttle Endeavour and Hopkins astronaut Sam Durrance were scheduled to return to Earth over the weekend, ending a historic astronomy mission that enabled scientists to gather an unprecedented wealth of information about the universe. "From my point of view this mission has been nothing short of absolutely spectacular," Arthur Davidsen, leader of the Hopkins Ultraviolet Telescope project, said during a news conference last week at the Marshall Space Flight Center in Huntsville, Ala. "We feel that we are likely to uncover some tremendous new secrets of the universe through these observations." Scientists plan to begin analyzing the treasure of data this week, but they collected enough information to stay busy for years. HUT was one of three ultraviolet telescopes in the Astro-2 observatory, which orbited the Earth for 15 and a half days, the longest space shuttle mission. It was a followup to the nine-day Astro-1 mission, on the shuttle Columbia in 1990. Astrophysicists could not have asked for a better mission. Not only did the observatory perform without a hitch, but scientists were treated to a series of cosmic coincidences that made the mission even more productive. ù Shortly after Endeavour's launch, a major volcanic eruption started on Jupiter's moon Io--perfect timing for the HUT team to study how the giant planet's atmosphere is affected by volcanic material from Io. ù Astronomers were stunned when they learned that a special type of galaxy that varies in brightness apparently was peaking at the ideal time for HUT astronomers, giving researchers extremely sharp spectrographic data. ù Soon they found themselves marveling at yet another instance of uncanny timing. An object called a cataclysmic variable was on the verge of going into a period of "outburst," when the objects increase dramatically in brightness. By comparing the data with information from Astro-1, scientists discovered that the object is dramatically cooler before outburst than it is right after an outburst. ù The Hopkins astronomers made history again later in the week, using HUT and the Hubble Space Telescope to simultaneously observe Jupiter. Hubble produced ultraviolet images, and HUT collected precise spectrographic data of the same region of the Jovian aurorae, similar to the Earth's Northern and Southern Lights. The timely volcanic eruption and last summer's collision of a comet with Jupiter heightened interest in those observations. But the most dramatic achievement of all was a string of unprecedented observations of two objects called quasars, located near the edge of the observable universe. "Whatever information we can provide will be extremely valuable to the understanding of cosmology and the history of the universe," said Dr. Davidsen, a professor in the Department of Physics and Astronomy. It was the culmination of his goal, conceived 17 years ago, to use a spectrograph in space to measure a range of light called the far ultraviolet spectrum, complementing the Hubble Space Telescope, which can observe a different portion of the spectrum. HUT's highest calling was to help scientists answer a fundamental question of cosmology: was an "intergalactic medium" of hydrogen and helium created in the Big Bang of cosmic creation? As light from the quasars shines through the void of intergalactic space, it should be absorbed by the intergalactic gas, producing a distinct spectrographic signature. Dr. Davidsen said the HUT team had collected so much good-quality data that astrophysicists will be able to make a serious attempt at solving the cosmic riddle. "It's too early to tell what the answer will be exactly," he said. "But either way, it's going to be very interesting. The data are just spectacular." Astronomers plan to use the data to learn details about how the universe mysteriously evolved from its original state of smoothly distributed matter to its present clumpy condition in which clusters of galaxies are distributed unevenly. Although the well-accepted Big Bang theory suggests that the primordial medium of hydrogen and helium should exist, its existence has never been confirmed, said Dr. Davidsen, who likens the gas to a "missing link" in the chain of events leading up to the present-day universe. Scientists said Astro-2 was a definite improvement over the first Astro mission. Although the pioneering mission was successful, it was troubled by computer glitches and problems with a system used to point the observatory. "We eventually accomplished some considerable success with Astro-1, but this Astro-2 mission is really in another category altogether," he said. "I feel like I'm floating on Cloud 9 now."
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