President Bush hailed the ``superb job'' of Columbia's astronauts today as they headed for Friday's homecoming after taking control of their ship when a bad navigation signal from the ground sent it into a slow spin. In a radio-phone call from the White House, the president termed their rescue of a huge science satellite ``a very exciting grab,'' and he invited the five crew members to meet with him at the White House after the mission. Commander Dan Brandenstein said the retrieval of the satellite was a highlight among several important accomplishments of the space journey. ``Well done _ we're proud of you,''' Bush said. The president also mentioned the erratic spin imparted to Columbia by the faulty signal when he said, ``I'm calling to congratulate you and the crew _ after all those somersaults _ for doing this superb job up there.'' Brandenstein had been roused from sleep during the night to manually override the shuttle's navigation system. He stabilized the craft until Mission Control transmitted correct guidance signals. There was no danger to the five astronauts, but ``we had a little excitement tonight,'' said flight director Bob Castle. After analyzing data, controllers reported that Columbia had made four rotations in yaw (side-to-side), one rotation in pitch (up-and-down of the nose and tail) and three-fourths of a rotation in roll. At times, they said, all movements were taking place simultaneously. Each rotation took two minutes, too slow for the astronauts to sense while asleep. Another flight director, Lee Briscoe, said it appeared that ``a couple of words got dropped'' in the navigation program, ``so the vehicle thought it was around the center of the Earth'' instead of repeatedly passing back and forth across the equator at a 28-degree angle. The incident happened Wednesday night, about 2{ hours before their scheduled wakeup. A false fire alarm also got them out of their beds Wednesday. A third wakeup, at the planned time, was music to their ears: a rendition of Washington and Lee University's fight song. One of the astronauts, David Low, is a graduate of the school. ``Good morning, Columbia, after what must have been a restful, or restless, night,'' the control center radioed. Brandenstein and pilot Jim Wetherbee successfully tested Columbia's flight control systems to make sure they were in good shape for returning home. During the 10-day mission the astronauts have deployed a Navy communications satellite and retrieved an 11-ton science laboratory that had orbited for six years. Snow was falling this morning at the landing site at Edwards Air Force Base, Calif., and about an inch had covered the desert before dawn. Briscoe said forecasters were watching the weather closely, but ``it still looks good for tomorrow.'' The pre-dawn landing is scheduled at 2:54 a.m. PST. Recent heavy rains have closed the public viewing area, and the space agency discouraged citizens from driving to the base to watch the touchdown. While Brandenstein and Wetherbee checked the shuttle's systems, mission specialists Bonnie Dunbar, Marsha Ivins and Low completed a series of medical and science experiments and began stowing them away. Castle said Columbia began its slow spin after an errant navigation signal from the ground caused six small steering jets in the shuttle's nose to fire on and off, the longest for two minutes. That sent the shuttle into an unwanted spin of about 3 degrees a second, or about one rotation every two minutes, Castle said. He said the navigation data had suffered radio interference during the transmission, but that an operator on the ground failed to catch it. Castle said that if nothing had been done, Columbia would have continued to rotate at that rate, but there would be no threat to the astronauts. ``I'm concerned about what happened because we have to find out what happened and correct it,'' Castle said. ``But I'm not real concerned. It was an error on the ground. Columbia did exactly what Columbia should have done.'' NASA spokesman Jack Kroehnke said the astronauts would not have felt the spin imparted by the six thrusters, part of a system of 44 steering jets on the shuttle. ``If we had not awakened the crew, they'd eventually have awakened themselves, I'm sure, and looked out to see the Earth view changing in the windows,'' Kroehnke said.
