UV telescopes: One dead, one revived

On Jan. 30, 13 months after NASA ended observations with the Extreme Ultraviolet Explorer spacecraft, the satellite plunged into Earth’s atmosphere and burned up over central Egypt.

Launched in 1992, the craft was the first mission to explore the heavens at ultrashort ultraviolet wavelengths, which can’t make it through Earth’s atmosphere. The observatory catalogued more than 1,000 sources of extreme-ultraviolet radiation within the Milky Way and was the first to record these emissions from another galaxy.

Another ultraviolet observatory, NASA’s Far Ultraviolet Spectroscopic Explorer (FUSE), is now faring much better than it was. Last December, the spacecraft shut down after the failure of two of its four reaction wheels, which keep the craft steady enough to make observations (SN: 1/12/02, p. 21: Milky Way galaxy: Cloaked in a hot shroud?).

But engineers found a way to avoid blowing FUSE. Although the reaction wheels can’t be repaired, software radioed to the spacecraft in late January appears to have circumvented the problem, says project scientist George Sonneborn of NASA’s Goddard Space Flight Center in Greenbelt, Md. Tests show that FUSE can now make accurate observations within two regions directly north and south of its orbit.

By the end of February, further improvements should allow the craft to expand its vision to half the sky, he says.

Even so, FUSE isn’t expected to resume regular operations for several months and NASA must still approve the funds to continue repairing it, Sonneborn notes.

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