ultraviolet_death_000922 WASHINGTON -- Extreme silent treatment. That's what NASA is giving the Extreme Ultraviolet Explorer (EUVE) -- much to the dismay of space scientists.
Despite being in tip-top shape and fully functional, EUVE is going to be put to sleep. The astronomical observatory will then drift through space, headed for a destructive plunge to Earth between late 2001 or early-to-mid 2002.
More worrisome is that pieces of the satellite are likely to survive the tumble from space.
Comet Hyakutake through the ultra-violet eyes of the EUVE satellite.
EUVE, in a sense, has already fallen: it has fallen victim to NASA budget pressures, prompting the space agency to pull the plug on the scientific spacecraft.
A special outside group of senior space research experts, established to review NASA
space science projects, recently advised the agency that EUVE was a mission of "low ranking" on a "science per dollar" basis. The panel recommended to NASA termination of EUVE at the end of fiscal year 2000, which is September 30th. "This type of review is even more and more important," said Ed Weiler, associate administrator for NASA's Office of Space Science before a House space subcommittee September 13. He told the lawmakers that EUVE would be silenced.
Weiler said that the decision can be tied to the launch increase of faster, better, cheaper spacecraft. "If we never turn off anything," he said, "we're going to wind up spending an awful lot of money to continue missions doing good science, not necessarily forefront research."
Alan Bunner, NASA science program director for the structure and evolution of the universe, told SPACE.com that "it's a simple matter of fact that the NASA money [for EUVE] is being turned off. The money stops flowing on September 30th."
Spectral success
EUVE was lofted into Earth orbit on July 7, 1992, atop a
Delta 2 rocket from Cape Canaveral, Florida. The spacecraft was placed into a circular, 328-mile (528 kilometer) orbit around Earth.Since then, the astronomical eye-in-the-sky has worked flawlessly for over eight years. It has churned out a steady stream of science finds in a mostly unexplored spectral window in astrophysics.
Extreme ultraviolet is a form of light that falls between X-rays and
ultraviolet radiation in the electromagnetic spectrum. For example, material heated to 5,000 degrees Fahrenheit emits visible light, like the sun. Material heated to 200,000 degrees Fahrenheit emits extreme ultraviolet radiation, which cannot be detected by the human eye.Instruments on EUVE have studied a range of objects from Earth orbit. Over 1230 extreme ultraviolet sources have been detected since EUVE's launch, many of those sources discovered serendipitously.
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Just last July, EUVE and the
Chandra X-ray Observatory were teamed to scan Comet LINEAR. The telescopic twosome discovered the first direct evidence for X-ray emissions due to interactions between the comet and solar wind.High hopes, but lights out
EUVE is well past its prime mission. It was scheduled to go dark in 1996. NASA made a decision to extend the EUVE mission through 1997. Then, in 1998, a go-ahead was given to extend the spacecraft's astronomical duties into 2000.
Hopes were high for playing the extended mission card for EUVE again, to the tune of around $1 million a year.
"This is very ironic given that NASA asked the University of California to take over operation of EUVE only three years ago as an experiment to lower mission operations costs, introduce innovative technologies, participate in the training of new young scientists and engineers. This experiment has been wildly successful."
But despite EUVE's ability to still provide an unprecedented view of the cosmos, now it's lights out for the spacecraft.
"Unfortunately, NASA appears to be about to turn off the EUVE mission, a scientifically productive and effective mission, 18 months before reentry," said Roger Malina, an astronomer and Director of the Center for EUV Astrophysics (CEA) at the University of California, Berkeley.
Malina directed the design and construction of EUVE's science payload. The CEA handles day-to-day EUVE operations.
"This is very ironic given that NASA asked the University of California to take over operation of EUVE only three years ago as an experiment to lower mission operations costs, introduce innovative technologies, participate in the training of new young scientists and engineers. This experiment has been wildly successful," Malina said.
EUVE was specially built to be retrieved via
a space shuttle. Instruments on the satellite were to be swapped out, replaced by another science package, then reboosted. Those plans never materialized, Malina said.Up hill battle
Several space scientists are now busy writing letters to NASA and Congress calling for an EUVE stay-of-execution. It appears, however, to be an uphill battle.
While funding to do EUVE science operations ceases at month's end, monies have been set aside for satellite close down operations, said Steve Howell, a space scientist at the Planetary Science Institute in Tucson, Arizona and chair of the EUVE Science Advisory Board.
"People will be doing some very low-level activities until roughly January. There will be no or little science done during that period," Howell said.
"Around the end of January, as now planned, basically we wouldn't communicate with the satellite anymore. It will then randomly fly around up there and does what it wants, until it burns up in a year or so," Howell said.
Short of Congress stepping in and telling NASA to keep EUVE alive, the satellite appears doomed, Howell said. In his view, the decision by the outside review board and NASA itself, while tough to swallow, should be the final word on EUVE.
Doomed decay
Unlike the Compton Gamma Ray Observatory, which was
deorbited into the Pacific Ocean last June, EUVE has no onboard propulsion system. So a controlled reentry is impossible.EUVE 's orbit is decaying quickly. It could enter Earth's atmosphere as early as October 2001.
One NASA report by Goddard Space Flight Center has estimated that numbers of EUVE leftovers are sure to survive the fiery fall and hit Earth. Among the items are large bolts, chunks of solar array equipment, and a battery pack.
That same Goddard study, completed last month and obtained by SPACE.com, reported that the EUVE debris would spread over an area larger than called for in NASA safety guidelines.
However, another review by NASA's Johnson Space Center found that any surviving EUVE hardware would fall within a much smaller "
debris footprint", well within NASA safety guidelines.
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