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Near the end. The UARS will stop transmitting data on 6 August.

Satellite Shutdown Stirs Controversy

NASA last week abruptly decided to shut down a venerable research satellite that has been gathering critical global climate change data for a decade. The decision, made to save money, surprised and angered atmospheric researchers, who were planning a festive 10th anniversary celebration next month for the Upper Atmosphere Research Satellite (UARS).

Launched in 1991, UARS monitors agents of global warming, such as water vapor and solar radiation. It also keeps tabs on chlorine and other chemicals that destroy stratospheric ozone. Although the satellite is well past its 3-year design lifetime, it is still beaming data from five of its 10 instruments. Project scientists had hoped to keep it operating until after the European Space Agency launches a new environmental monitoring satellite, which was planned for this fall but has been put off.

NASA officials say the shutdown is probably only the first in a series. Several years ago, the agency put industry in charge of satellite operations. But when planned savings never materialized, NASA managers had to figure out how to cut costs. Agency officials now intend to shut off UARS's instruments beginning the week of 6 August, eliminating the project's $10 million per year operating costs. "I'm shocked," says Paul Crutzen of the Max Planck Institute for Chemistry in Mainz, Germany, who shared the Nobel Prize in chemistry for discovering the ozone threat. "It would be a tremendous loss."

NASA also must decide how to dispose of the 7-ton satellite. Most large satellites--such as the Mir space station--are designed so that they can be guided into the Pacific Ocean. But UARS was built in an era when engineers envisioned the space shuttle routinely returning scientific spacecraft, and it lacks the thrust capacity to be placed on a path for controlled reentry. The shuttle is now busy building the international space station, however, and it may be tough to reserve one to reclaim a defunct satellite as well as find the $50 million needed for such a mission.

Left on its own, UARS would remain aloft for another 20 years. But a slow decay of its orbit increases the chances that it will break into large chunks containing toxic batteries and fuel. Alternatively, NASA could adjust the orbit of the spacecraft in the coming year for the best possible flight path and vent the toxic fuel, but a truly controlled reentry is not possible. "There's no guarantee where it would come down," says Paul Ondrus, project manager for operational missions at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

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