Engineers at NASA Goddard Space Flight Center in
Greenbelt, Md., predict a 7,000-pound spacecraft could re-
enter the Earth's atmosphere as early as 10 p.m. EST on Jan.
30 or as late as 7 a.m. EST on Jan. 31.
NASA's Extreme Ultraviolet Explorer (EUVE) is currently 200
kilometers (124 miles) above the Earth with a descent rate of
25 kilometers (15.5 miles) a day. The estimated debris field
is expected to be 800 to 1,000 kilometers (500-625 miles).
"The probability of the few EUVE surviving pieces falling
into a populated area and hurting someone is very small. It
is more likely that the small pieces will fall into the ocean
or fall harmlessly to the ground," said Ronald E. Mahmot,
Project Manager for Space Science Mission Operations at
Goddard.
Unlike the Compton Gamma Ray Observatory, which was safely
de-orbited June 4, 2000, EUVE does not have an on-board
propulsion system to allow engineers to control its re-entry.
Much of EUVE will burn up in the atmosphere before ever
reaching the ground. However, estimates show that up to nine
objects ranging from approximately four to 100 pounds may
survive re-entry. Much of this debris is made of titanium and
stainless steel.
EUVE will start to break up when it falls to within 80
kilometers (50 miles) of the Earth. At this point, EUVE will
have only four or five 90-minute orbits left before re-
entering the Earth's atmosphere. Engineers will not know the
re-entry point until approximately 12 hours prior to impact.
EUVE is in a 28.5-degree orbit and could re-enter in any
location within this orbit range. This ranges includes areas
as far north as Orlando, Fla., and as far south as Brisbane,
Australia.
EUVE was launched on June 7, 1992. Science operations ended
for the spacecraft in December 2001. During its early years,
EUVE was operated from Goddard. In 1997, control of EUVE was
transitioned from Goddard to the University of California,
Berkeley and remained there until the program's termination
in 2001. Slated for only three years, EUVE was operational
for eight. NASA twice extended its scientific mission.
During its eight years in orbit, EUVE successfully opened a
new window on the cosmos and helped to bridge the gap in our
understanding of the extreme ultraviolet spectrum. Rather
than seeing about 24 nearby objects as many predicted, EUVE
observed more than 1,000 nearby sources, including more than
three dozen objects outside our galaxy.
Additional background information about EUVE is available on
the Internet at:
http://heasarc.gsfc.nasa.gov/docs/euve/euve.html
Related Links
17 November 2000: Extreme Ultraviolet Light Mission Comes To An End, NASA HQ
18 November 2000: Extreme Ultraviolet Explorer (EUVE) To Be Shut Down, SpaceRef
"After more than 8 years of non-stop flawless performance, NASA has decided to shut down the Extreme Ultraviolet Explorer (EUVE). The reason? As NASA sees it, money is short, the EUVE has more than accomplished its stated goals, and NASA needs to direct its financial resources to other projects. The EUVE is now in a "minimal observation mode" and will be turned off in January 2001."
31 October 2000: End of EUVE Announcement, University of California Berkeley
3 AUgust 2000: Extreme Ultraviolet Explorer (EUVE) Funding to End, NASA HQ
"We have received your appeal, as well as the related e-mail writing campaign. We have considered your arguments as well as those of other writers, but we see no basis for changing our decisions, which are based on the rankings of EUVE in the past two comparative reviews."
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