Having coaxed all the life they can out of an 8-year-old ultraviolet light-detecting space telescope, scientists will reluctantly turn it off later this month.
After that, NASA's Fuse observatory will be "just another piece of space junk," orbiting the earth every 100 minutes until it falls back to Earth in about 30 years, said Bill Blair, the Fuse operations chief and an astronomy professor at Johns Hopkins University.
Fuse, short for Far Ultraviolet Spectroscopic Explorer, has been tuned to the short ultraviolet wavelengths that the Hubble Space Telescope can't see. Fuse has complemented its more famous cousin, detecting a circle of hot gas that surrounds the Milky Way and finding evidence of molecular hydrogen in Mars' atmosphere.
The $108 million observatory has given more than expected when launched in 1999. NASA extended Fuse's mission three times.
Its scientific instruments still have years of life in them, but are no longer able to be pointed at objects of interest, leading to the decision to shut it down Oct. 18, Blair said.
"So that's the sad part, that it was still very scientifically capable," he said. "But I don't think any one of us could complain about the run we got out of this satellite."
Slowly, the telescope's four reaction wheels, which control its direction, had begun to fail.
"Once we lost that last wheel, basically we could hold it steady in a safe mode, but we couldn't do any science," Blair said.