JUPITER WATCH INCLUDES TWO HOPKINS ASTRONOMERS By Emil Venere Hopkins astronomers Paul Feldman and Doyle Hall are taking advantage of Comet Shoemaker-Levy 9 to study Jupiter as they never have before. Dr. Feldman, a professor of physics and astronomy, and Dr. Hall, an associate research scientist, have observed the Jovian system for years, using satellites to record ultraviolet light from the planet and its moons. But Shoemaker-Levy has suddenly made Jupiter a scientific priority, meaning that astronomers who use satellites to observe the giant gaseous planet are receiving more precious observing time than they usually do. And for good reason. The cometary collisions are providing some of the most exciting astronomical research opportunities in the history of science. Shoemaker-Levy is getting plenty of media attention. That would have been evident to anyone who tried to make a turn onto San Martin Drive on July 16, the day the collisions began. The road was closed to accommodate all the vehicles from television crews and journalists congregating at the Space Telescope Science Institute. "This event was not a fizzle, as had been predicted by many astronomers," Dr. Feldman said. Professor Feldman and Dr. Hall are working with a team of astronomers studying Jupiter with a satellite called the International Ultraviolet Explorer (IUE), and Dr. Feldman is involved with the Hubble Space Telescope's comet observation team. Dr. Hall also heads a team of Hopkins scientists who are observing Jupiter with another orbiting instrument, a satellite called the Extreme Ultraviolet Explorer (EUVE), operated by the University of California at Berkeley. But the IUE has a distinct advantage over the other two satellites. It orbits the Earth from a much farther distance -- a geosynchronous orbit about 22,000 miles above the planet. That means the satellite has a clear view of Jupiter all the time. Other space instruments, like EUVE and Hubble, are in a low-Earth orbit, only a few hundred miles high, and will have their view of Jupiter blocked by Earth at times. Scientists viewing Jupiter with IUE normally have to compete for viewing time with hundreds of scientists from the United States and Europe. Ordinarily, they get observing time two or three times a year, perhaps a total of 24 hours each time. But the researchers are now given carte blanche to observe the Jovian system. They began shortly before the collisions started and plan to continue until mid-August, when Jupiter's line of sight will get too close to the sun to make observations practical. "We are simply taking advantage of this opportunity to enhance our knowledge of Jupiter, using the techniques and tools that we've been using all along," Dr. Feldman said. IUE is operated by NASA, the European Space Agency and the Science and Engineering Research Council of the United Kingdom. Hopkins scientists have been using IUE to study Jupiter since 1979, making a detailed record of the Jovian system's ultraviolet spectrum. Therefore, any changes that result from the comet's impact will be obvious. The scientists will be able to identify any material introduced to the system from the comet, which will help them to determine what the intruder is made of. The astronomers also will use ultraviolet data to analyze how the impacts affect Jupiter's atmosphere and its southern aurora, a colorful display of charged particles from the sun interacting with Jupiter's magnetic field. That research will tell scientists something about how large the impacts were and how much energy they deposited. Coupled with research being done at observatories around the world, scientists wll reap a bumper crop of information about the complex Jovian system. "There is already a lot of new Jupiter science coming out of this and many new discoveries have already been reported in the press, but it will take months to distill the data and reach firm conclusions," Dr. Feldman said.
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