The roller-coaster saga of the Astro-1 space shuttle mission took another stomach-churning plunge early yesterday with the shutdown of an essential computer terminal the astronauts had used with great success to point the instruments at celestial targets Wednesday night.
But the National Aeronautics and Space Administration, after a frenzied day of trouble-shooting, was successful yesterday evening in restoring the $150 million observatory to limited operation through a complex combination of ground controls from Marshall Space Flight Center and manual fine-pointing by the astronauts.
"One thing I've learned from this mission is, if you don't like your mood right now, just wait 10 minutes and it will change," said astronomer William Blair, a member of the Johns Hopkins University science team that built and directs the Hopkins Ultraviolet Telescope.
Astro's three ultraviolet telescopes were idled at 7 a.m. yesterday when the seven astronauts -- including Hopkins astronomer Samuel T. Durrance -- smelled a hot odor coming from one of the two "data display units," or DDUs, in Columbia's aft flight deck area.
Those units link the separate on board computers controlling the three telescopes and the automatic pointing platform on which they are mounted. The other terminal broke down soon after launch Sunday from a similar heating problem.
The astronauts had been using the remaining terminal to compensate for a continuing problem with the automated Instrument Pointing System by grossly pointing the telescopes through computer commands, then manually holding them on target with a joystick control.
That was the method Dr. Durrance successfully employed Wednesday evening to obtain an unprecedented 30-minute observation with HUT of the brightest quasar in the sky, 3C273, a billion light years away in the constellation Virgo.
"It gave us an indication of the incredible potential of HUT and showed it's working flawlessly," said Hopkins astronomer Arthur F. Davidsen, lead scientist for the telescope since its inception 13 years ago. "It's frustrating that we can't fully capitalize on that."
The other ultraviolet telescopes -- the Wisconsin Ultraviolet Photopolarimeter Experiment and the Ultraviolet Imaging Telescope -- also made observations, as did the Broad Band X-Ray Telescope, mounted separately and pointed by commands from Goddard Space Flight Center in Greenbelt.
NASA officials were uncertain yesterday if the two DDUs could be fixed, although they have in the Astro crew a veteran astronaut and astronomer, Robert Parker, who earned the nickname "Mr. Goodwrench" for his prowess at repairing broken equipment during another shuttle flight.
The unit that went down Sunday was found to have lint blocking air intakes in its cooling system, and the crew vacuumed it away. But an attempt to restart the computer terminal yesterday afternoon resulted in the same overheating.
"We probably won't continue to look at that unit, and we're still thinking about the other one," said flight director Al Pennington. "We're prepared to do this whole thing by ground command if we have to."
Despite the problems with Astro-1, NASA plans to proceed this morning with a special "Space Classroom: Assignment the Stars," a science lesson taught from space by the astronomers aboard the shuttle.
Thirty science students from Howard and Prince George's counties will be visiting Goddard for the lesson, as will 15 Alabama students at Marshall Space Flight Center. After the lesson, the students will also participate in a live question-and-answer session with the astronauts.