Arthur F. Davidsen, an astronomer whose discoveries were fundamental to human understanding of the structure of the universe and who literally took Johns Hopkins into orbit as the driving force behind the Hopkins Ultraviolet Telescope, has died.

Davidsen, 57, was professor of physics and astronomy and former interim dean of faculty of the Krieger School of Arts and Sciences. He succumbed on Thursday, July 19, to complications from a lung disorder.

Arthur F. Davidsen in a 1997 file photo

Davidsen made a number of pioneering contributions to ultraviolet astronomy and to the study of material in the vast gulfs between galaxies. He was also the principal driving force behind the successful Hopkins effort to get the Space Telescope Science Institute, the facility that operates the Hubble Space Telescope and is planning for its successor, placed on its campus.

"We were very much the underdog," reminisced Paul Feldman, chairman of the Department of Physics and Astronomy, of the competition for the institute in the late 1970s. "Everyone knew it was going to Princeton, and we were a real long shot."

At the time of the competition, Feldman noted, the department was formally known only as the Physics Department.

"Winning the institute really put us on the map in astronomy, and Arthur was the single most important person in the successful effort to get the institute here," Feldman said.

Davidsen was the principal investigator for the Hopkins Ultraviolet Telescope, an observatory that flew aboard the space shuttle in 1990 and 1995. Davidsen and the other astronomers designed HUT to study previously unexplored regions of ultraviolet light rich with information about distant stars and quasars, star clusters and even objects in our solar system like Jupiter's moon Io.

A permanent exhibit set to open in September at the Smithsonian's National Air and Space Museum will feature HUT prominently for its contributions to astronomers' understanding of the tenuous material between galaxies.

"HUT demonstrated that the intergalactic medium--the environment out of which galaxies formed long ago--is not uniform but clumpy," said David Dvorkin, curator of the new exhibit, which is known as Explore the Universe.

"In addition, the abundances of the primordial elements in the intergalactic medium, as captured in HUT data and analyzed at Johns Hopkins, fits the general picture of a hot Big Bang model very nicely, adding new evidence that science is on the right track for elucidating the master narrative of the universe," Dvorkin said.

Davidsen obtained his A.B. in physics from Princeton in 1966 and immediately began a tour of duty in the Navy. In 1971 he became scientific liaison officer for the Naval Research Laboratory, a position that, according to Feldman, put him in the unusual position of effectively completing a postdoctoral fellowship before entry into graduate school.

In 1975, Davidsen went straight from a doctorate at the University of California, Berkeley to a position as assistant professor of physics at Hopkins.

"That was a pretty risky decision on the part of the department, but obviously one that paid off very well," said Bruce Margon, associate director for science at the Space Telescope Science Institute.

Among Davidsen's important early contributions was obtaining the first ultraviolet spectrum of a quasar via a rocket-mounted telescope.

"He was still just a fuzzy-cheeked assistant professor when he did that," said Margon. "That was the achievement that won him the American Astronomical Society's Helen B. Warner Prize in 1979."

The Warner Prize, among the most significant in astronomy, is awarded only to astronomers under the age of 36 who have made outstanding scientific contributions.

Margon said Davidsen was unusual in that he made important contributions both to observational astronomy and to theoretical astronomy.

Davidsen began working on the HUT telescope project in the late 1970s. He and his colleagues were awaiting launch of the telescope aboard the next space shuttle mission when the shuttle Challenger exploded in 1986, delaying the project.

When the shuttle finally took HUT up in 1990 for what was thought to be its only flight, researchers discovered during the mission that instabilities in the platform where HUT was mounted would make it very difficult to study the faint ultraviolet light sources that were central to Davidsen's research program.

Rather than risk time in space on an effort to further his research that might fail, Davidsen decided to let HUT be used for observations of brighter light sources that were more important to his junior colleagues, according to Bill Blair, a research professor of astronomy at Hopkins.

"Arthur stood aside for the greater good, and that was a very difficult and courageous decision for him to make," Blair said. "But he always showed great concern for his junior colleagues."

Fate gave Davidsen another chance when NASA elected to send HUT up in the space shuttle again in 1995, and he was able to get the observations he needed to characterize the tenuous and elusive gas between galaxies.

Davidsen had been hoping for a third opportunity to fly HUT on the shuttle but was proud to learn that it would be included in the Smithsonian exhibit.

At the time, he smiled wistfully and said, "I told my son, who's a freshman in college, that HUT was going to Air and Space, and he said, going there was much cooler than going into orbit one more time. I can't go that far myself, but I certainly am thrilled and pleased because it validates the importance of the project."

Davidsen's other lasting contribution to the Hopkins campus came when he served as founding director of the Center for Astrophysical Sciences, which helps organize large astronomical research projects at Hopkins. He was interim dean of the Krieger School of Arts and Sciences from January to June 1997.

At the time of his death, Davidsen was chairman of the advisory council for the Sloan Digital Sky Survey, an important new multi-institutional project dedicated to making the first comprehensive digital encyclopedia of a large fraction of the sky.

Davidsen's academic honors included election as a fellow of the American Association for the Advancement of Science and of the American Physical Society.

Davidsen is survived by his wife, Frauke Davidsen; sons Andrew and Austin Davidsen; stepsons Nick Tischler, of San Francisco, and Jesse Tischler, of Boston; and a sister, Sylvia Klecak, of East Meadow, N.Y.

A memorial service for Davidsen will be held at 3 p.m. on July 29 at the Second Presbyterian Church at 4200 St. Paul St. A reception will follow. In lieu of flowers, memorial donations may be sent to the Physics and Astronomy Department, Johns Hopkins University, Baltimore, MD 21218. Please note on the donation that it is in memory of Arthur F. Davidsen.