From: Goddard Space Flight Center
Posted: Tuesday, January 29, 2002
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:
"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."
"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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