Stars Smile on Astro-2 and HUT Team By Emil Venere A combination of expert planning and lucky timing have made the Astro-2 observatory a dream come true for Hopkins astrophysicists. "Absolutely fantastic," said Arthur Davidsen, professor in the Department of Physics and Astronomy, who leads the Hopkins Ultraviolet Telescope project. "Just great," said Gerard Kriss, HUT project scientist. "We are getting dynamite stuff," said another Hopkins astronomer, William Blair. Nobody really expected the orbiting observatory to be this successful. "The gods are with us on this mission; I cannot believe it," Dr. Blair added. HUT is one of three ultraviolet telescopes in the Astro-2 observatory, now being operated in the space shuttle Endeavour, which is scheduled to land 2:54 p.m. Friday, March 17, at Kennedy Space Center in Cape Can-averal, Fla. Since Endeavour took off early March 2, scientists have been treated to a series of unusual cosmic events, accented by the telescope's exceptional performance. With each successive day came another revelation about the observatory's good fortune. ù HUT made a string of unprecedented observations of an object near the edge of the universe, for research that may at last find the hypothetical "intergalactic medium" presumably produced at the beginning of time. ù Shortly after Endeavour's launch, astronomers in Hawaii discovered a major volcanic eruption taking place on Jupiter's moon Io--perfect timing for scientists using HUT's unique ability to study the Jovian system. ù Last Tuesday morning HUT 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. The object, called a Seyfert galaxy, had grown five times brighter than it was during the Astro-1 mission in December 1990. ù The next day, HUT astronomers 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. Astronomers had observed the same cataclysmic variable with Astro-1, right after it had finished going through an outburst, measuring its temperature at about 37,000 degrees. By comparing the two observations, scientists learned that the object is drastically cooler before outburst than after outburst. Astrophysicists are eager to begin analyzing data, which will enable astronomers to make precise temperature measurements, yielding insights into the physics behind cataclysmic variables. ù Last Thursday brought another first in astronomy. Scientists used two different types of space telescopes--HUT and the Hubble Space Telescope--to observe Jupiter. Hubble produced ultraviolet images, and HUT simultaneously collected precise spectrographic data of the same region of the Jovian atmosphere. Those observations were made even more important because of the timely volcanic eruption on Io and last summer's collision of a comet with Jupiter. All this historic science research was punctuated by a dose of levity. Last Wednesday morning WJZ-Channel 13 conducted a a live interview via satellite with Hopkins astronaut Sam Durrance. Dr. Durrance's family was on hand in the studio for the half-hour special. He and his son, 13-year-old Benjamin, engaged in casual conversation before thousands of viewers. "Have you been playing your guitar?" the scientist asked his son. "Yeah, it's pretty cool," the boy answered. "Hey, dad? Can you buy me a new amp?" By the sixth day of Astro-2, only one-third of the way through its planned 16-day mission, scientists already had collected more data than they did during the entire nine-day Astro-1 mission. "It feels like we are drinking from a fire hydrant," Dr. Davidsen said at the time, noting that scientists were stockpiling the treasure of data for analysis later. HUT astronomers don't have the luxury of slowing down long enough to interpret the spectrographic windfall. It became apparent early in the mission that the HUT team would be successful at observing a quasar 10 billion light-years away, literally near the edge of the observable universe. That meant scientists would probably be able to achieve HUT's major objective, searching for the intergalactic medium of helium and hydrogen presumably produced in the Big Bang of cosmic creation. Astronomers have not yet established the existence of such gas. Dr. Davidsen hopes to prove its existence with HUT. But things also were happening in our own cosmic neighborhood. Paul Feldman, a HUT astronomer, said scientists were elated about Io's unexpected volcanic outburst. Ever since the Voyager spacecraft recorded a volcano erupting on Io in 1979, astronomers on Earth have been using infrared techniques to look for "hot spots" on the moon to detect volcanic activity. Shortly after Endeavour's launch, Dr. Feldman turned on his computer to read his latest electronic mail. To his astonishment, the mail included a report from NASA's Infrared Telescope Facility on Mauna Kea, Hawaii. The mail alerted all astronomers of a major eruption on Io, asking that they train their telescopes on the Jovian system. The HUT team did just that, recording important spectral data from the moon, said Dr. Feldman, a professor in the Department of Physics and Astronomy. He called the volcanic eruption a "fortuitous experience that had us all very, very much excited ... and even more excited when we were able to get a successful observation of the satellite." A few days later astronomers used a camera on the Hubble Space Telescope to take ultraviolet images of Jupiter while HUT recorded spectrographic data from the same part of the Jovian atmosphere. The telescopes focused on the planet's auroras, colorful displays of charged particles at Jupiter's polar regions similar to the Earth's northern and southern lights. The observations were especially important because of Io's volcanic eruption and last summer's collision of Comet Shoemaker-Levy 9 with Jupiter. "There is an enormous amount of energy being put into the atmosphere," Dr. Feldman said. "Clearly, these energetic particles are controlling, to a large extent, the fate of the upper atmosphere of Jupiter. We are trying to get a better idea of how it responds to changes."
Go to Gazette Homepage