The Hopkins Ultraviolet Telescope, a special telescope built by university researchers for use in orbit aboard the space shuttle, will fly again this fall for the first time since 1995.
It's not quite the flight that the project's principal investigator, Arthur Davidsen, professor of physics and astronomy in the Krieger School of Arts and Sciences, had hoped for, but he's still quite pleased with the new journey.
HUT was removed last Thursday from the Bloomberg Center for Physics and Astronomy at Homewood for shipment to the Smithsonian's National Air and Space Museum in Washington, D.C., where it will be hung from the ceiling as part of a new exhibit, "Explore the Universe."
"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," Davidsen said, smiling wistfully. "I can't go that far myself, but I certainly am thrilled and pleased because it validates the importance of the project."
HUT, originally conceived in the late 1970s, was shaped by the then-prevalent idea that the best way to get an observatory beyond the obscuring effects of Earth's atmosphere was to fly it on the space shuttle for several days at a time, bring it back to Earth for modifications and improvements, and await another opportunity to fly aboard the space shuttle.
That approach was later dropped by NASA in favor of permanently orbiting observatories like the Hubble Space Telescope, the Chandra X-Ray Observatory and the Far-Ultraviolet Spectroscopic Explorer, a NASA satellite observatory operated by Hopkins.
Davidsen says HUT, the first major orbital observatory to be built at Hopkins, helped pave the way for FUSE, which also was built at Hopkins.
"HUT was one of our first forays into something that really required a lot of support people, administrators and engineers and so on," Davidsen said. "We clearly couldn't do it with just a couple of professors and some students."
The optical and mechanical components of the HUT telescope came together in the early 1980s in the basement of what was then Rowland Hall (now Krieger Hall). HUT is 14 feet long and four feet in diameter and weighs about 1,700 pounds.
"Getting it out of there was no mean feat," remembered Davidsen. "We took bricks out of walls to get it around corners. Just a few bricks."
For transport, first to Hopkins' Applied Physics Lab for installation of electronics and later to Florida for launch, HUT was packaged in a special box and loaded on a custom-built dolly.
"This dolly is like a Mercedes. It cradles HUT, and keeps it comfortable," Davidsen said, and then added, smiling, "It wasn't really like a Mercedes, but it cost about as much."
HUT was packed with four other telescopes into a space shuttle cargo bay and actually was waiting on the launch pad in Florida in January 1986, when the Challenger exploded and brought the space shuttle program to a halt for several years.
Nearly five years later, HUT finally had its chance to fly aboard the space shuttle Columbia in December 1990. HUT went up with four other telescopes for a mission called Astro-1. Also aboard the shuttle was a member of Davidsen's research team, Samuel Durrance.
Durrance and others used HUT to observe 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.
After Astro-1, HUT was brought back to Hopkins for modifications and storage until the Astro-2 mission, which flew on the space shuttle Endeavor in March 1995. Durrance and others again used the telescope to study a wide range of subjects, but a primary focus was measuring the intergalactic medium. This medium, which consists of the gas produced by the Big Bang that hasn't condensed into stars and galaxies, was one of the primary reasons Davidsen originally proposed HUT. The results from Astro-2 gave astronomers some of their first solid data on the intergalactic medium.
"HUT demonstrated that the intergalactic medium--the environment out of which galaxies formed long ago--is not uniform but clumpy," said David DeVorkin, curator of the new exhibit at the National Air and Space Museum that will feature HUT.
"In addition, the abundances of the primordial elements in the intergalactic medium, as captured in HUT data and analyzed at Johns Hopkins, fit 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," DeVorkin added.
As a nostalgic Davidsen prepared early last week to have HUT rolled out of the storage room in Bloomberg where it's been kept since 1995's Astro-2 mission, he expressed a mixture of mild regret that HUT hadn't been able to go up on the shuttle again and pride that HUT's observations will make the telescope the Physics and Astronomy Department's first major contribution to the National Air and Space Museum.
"It was two decades of work, and it produced an experiment of great cosmological significance," he said. "I think we've mostly learned what we're going to learn from the data gathered by HUT, but there are still some pockets of effort six years later where people are looking at or re-examining various things in the data."
"Explore the Universe" is scheduled to open at the Smithsonian's National Air and Space Museum on Sept. 21, 2001.