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,
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
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
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
"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: