Columbia's astronauts today lost their only working computer terminal for operating their $148 million Astro observatory, shutting down their star-gazing efforts.
The flight deck computer shut down automatically after the crew smelled something burning early this morning. The same thing happened Sunday, when a duplicate terminal overheated and turned off.
No smoke was reported in the cabin either time. There was no danger to the crew, but this time their observing was brought to a halt.
During the 12-hour shutdown, mission scientist Ted Gull said, technicians will be devising a complex plan for controlling Astro's three ultraviolet telescopes from the ground. If it works, the automatic pointing system will be operated from the Johnson Space Center in Houston, while scientists at the Marshall Space Flight Center in Huntsville, Ala., operate the three ultraviolet telescopes and monitor their performance.
Because of time lags in the remote operations, however, the shuttle astronauts will use manual controls and television monitors, which are still working, to help find target stars and keep them from drifting out of view.
"We know it's going to be difficult, but we're going to give it a try to see if we can do science for the remainder of the mission," said Gull. Columbia is to land Tuesday.
"I'm not trying to be 100 percent positive, because, believe me, we are moving into ground at this point that we have not simulated. But we are not panicked. We see a solution," Gull said.
The computer failures do not directly affect Astro's Broad Band X-ray Telescope, which was always under ground control. But it, too, was shut down as a precaution. Gull said its operations would resume as soon as possible.
Gull said technicians were still trying to determine whether the failed computer terminals could be salvaged. If they can't, the cumbersome nature of efforts to control the telescopes from the ground will greatly slow the pace of observations, which had been accelerating as scientists overcame problems with the telescope pointing system.
This latest disappointment left astronomers frustrated. It came just as the Astro Observatory was completing its most successful 12-hour shift yet, having completed 64 percent of the planned observations, up from 35 percent yesterday.
"There's no end to it, is there?" said Arthur F. Davidsen, lead astronomer of the Hopkins Ultraviolet Telescope team.
Davidsen learned of the failure at breakfast today, just 12 hours after successfully completing his most critical observation of the mission.
At 6:40 p.m. yesterday, astronauts aboard Columbia locked their instrument onto 3C273, a brilliant quasar in the constellation Virgo.
More than a billion light-years beyond the outer edge of our Milky Way galaxy, it shines with the luminosity of 100 million suns.
Davidsen first observed 3C273 in 1977, using a telescope mounted on an unmanned rocket. He thus became the first astronomer on the planet to observe a quasar -- or anything else outside our galaxy -- in the ultraviolet.
He glimpsed the quasar for only four minutes before the rocket fell back to Earth. But the feat won him the Helen B. Warner Prize in 1979, astronomy's equivalent of the Nobel Prize.
Last night, he got his long-awaited second look at the object. The 30-minute observation may provide the first confirmation of the theory that such quasars are fueled by the destruction of stars being are drawn into super-massive black holes at the cores of giant galaxies.