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The newspaper of The Johns Hopkins University July 6, 2004 | Vol. 33 No. 39
FUSE at 5: Satellite's Scientific Findings Continue to Soar

Astronomers watch the launch of a model rocket marked 'FUSE Fifth Anniversary.'

By Lisa De Nike

NASA's Far Ultraviolet Spectroscopic Explorer satellite reached a major milestone on June 24: the five-year anniversary of its launch atop a Delta-II rocket from Cape Canaveral, Fla.

The 18-foot-tall, 3,000-pound satellite continues to operate from its perch nearly 500 miles above the Earth's surface, gathering unique data about everything from planets and nearby stars to galaxies and quasars billions of light-years away.

Groundbreaking science done during FUSE's five years in orbit includes a first-ever observation of molecular nitrogen outside our solar system, confirmation of a hot gas halo surrounding the Milky Way galaxy and a rare glimpse into molecular hydrogen in Mars' atmosphere, among other findings. By its fifth anniversary, FUSE had collected more than 47 million seconds of science data on more than 2,200 unique objects in the cosmos.

"The sheer magnitude and amount of scientific work that is being produced using FUSE is beyond even what we had imagined," said Warren Moos, FUSE's principal investigator and a professor in the Department of Physics and Astronomy in the Krieger School of Arts and Sciences. "Scientists working with FUSE have produced a steady flow of papers — a half dozen a month — each representing a major scientific study. What has been accomplished is extremely impressive and very satisfying."

Designed and operated by a team of engineers and scientists at Johns Hopkins, FUSE is the largest astrophysics mission NASA has ever handed over to a university to manage. The project also includes key contributions from the Canadian and French space agencies.

"Astronomers are using FUSE to produce very exciting and unexpected results," said George Sonneborn, FUSE project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "FUSE has discovered a new component of the Milky Way galaxy, is charting very hot gas in the vast regions of universe between distant galaxies and is probing the nature of disks of gas and debris around young stars where planets may form."

FUSE comprises four telescopes that function as a single instrument, dissecting far-ultraviolet light from distant objects into high-resolution spectographic information used by astronomers around the world.

With more than 10,000 times the sensitivity of its predecessor, the Copernicus satellite in the 1970s, FUSE complements the Hubble Space Telescope by observing light at wavelengths too short for that instrument to see. Since its launch, astronomers have used FUSE to study stars and nebulas in nearby galaxies, to discover a new component of the Milky Way galaxy and even to probe the vast regions of space between distant galaxies in the universe.

Despite the obvious successes, there have been times over the past five years when serious problems threatened the satellite's pointing control system and thus the mission itself. In late 2001, two of the device's four reaction wheels — components that point the satellite's telescopes and keep them steady — stopped working, leaving the mission in peril. Rather than close up shop as some feared, FUSE scientists and engineers collaborated intensely for two months and devised a solution: using a combination of software and other hardware to mimic the functions of the missing wheels.

William P. Blair, FUSE's chief of observatory operations and a research professor at Johns Hopkins, said, "It's been a real roller coaster ride. But we've overcome the problems, and, if anything, FUSE is now working better than ever. It's something to be proud of."

That sense of pride was evident on June 24, when about 120 astronomers, scientists and other people associated with FUSE gathered at the Bloomberg Center for Physics and Astronomy on the Homewood campus for an informal noontime luncheon celebrating the satellite's five successful years producing groundbreaking science.

Among the guests were David Mengers, a NASA/Goddard lead engineer who worked on FUSE for nine years before retiring, and Dennis McCarthy, who served as FUSE's program manager during its development phase and who is widely credited with the project's success. (McCarthy now works for Swales Aerospace.)

Jonathan Bagger, chair of the Henry Rowland Department of Physics and Astronomy at Johns Hopkins, briefly remarked on the success of the mission.

"I can't believe it's been five years already," said Bagger, to applause. "It's been a time of tremendous scientific productivity, and we are very happy and proud."

In honor of the anniversary, Blair — sporting his 1999 "Let's Do Launch" cap replete with a rainbow-hued FUSE patch and a NASA insignia — launched a model rocket emblazoned with the words "FUSE Fifth Anniversary" on its side after a countdown timed to coincide to the minute with the actual FUSE launch five years ago.

"Welcome to launch date plus five," he said, lighting the wick and sending the model into the hot summer sky above the Bloomberg Center's stone courtyard, to which it returned moments later by plastic parachute.

Blair then recounted for the crowd some significant FUSE statistics.

"It's made 26,000 orbits and traveled 1.1 billion kilometers," he said. "There are 700 total papers in the literature mentioning FUSE, and we're not done. It will be a tremendous legacy."

For more information on FUSE, go to:


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