Those Balky Computers Again

By Frederic Golden

After a splendid voyage, Columbia returns tardily to earth

Only seconds after the space shuttle touched down on the California desert last week, a playful voice crackled from the radio at Mission Control in Houston. "Columbia," it said, "we've got some good news and bad news for you. The good news is, we've had lots of beer waiting for you. The bad news is, we drank it eight hours ago."

NASA, of course, does not permit alcohol aboard its spacecraft or on its facilities, but last week, after Columbia's harrowing, computer-plagued final day in orbit, the space agency had good reason to splash everyone with champagne. Sweeping out of the skies in the fading glow of a setting sun, the space shuttle settled gently onto Edwards Air Force Base's Runway 17 in the California desert with the "right on the numbers" precision only a master pilot like John Young, 53, America's premier astronaut, can muster. For seven hours and 50 minutes before that landing, however, flight controllers worked frantically hi Houston to get Young, his five crewmates and their prize scientific cargo, the European-built $1 billion Spacelab, safely back to earth. During the unscheduled extension of the 166-orbit flight, the shuttle's longest, some California radio stations had even begun speculating ominously that the ship might become marooned in space.

The electronic glitches that led to those fears began on Columbia 's ninth day in orbit as it circled 155 miles above the earth. The flight had already been lengthened by 24 hours to give ground scientists more experiment time. This was made possible by the shuttle's unexpectedly low use of its "consumables" (oxygen, fuel, electric power). But when Columbia, in preparation for its descent, fired the small maneuvering rockets, or thrusters, hi its nose, the jolt rocked the ship. The usually laconic Young said that it sounded like a "howitzer blast going off in your backyard."

At that instant, the spacecraft's No. 1 computer, responsible for directing the orbiter's navigational and guidance systems, as well as general housekeeping duties, "crashed," or shut down. To the relief of Houston controllers, the No. 2 computer promptly took over. Indeed, under NASA's suspenders-and-belt philosophy, the orbiter is equipped with four electronically linked computers, plus an independently operating backup. Any one of these machines can take charge of the shuttle. About four minutes later, however, after the thrusters fired again to slow the ship, the second computer also stopped.

For three or four minutes, there was no computer at all steering the orbiter. The failure was an echo of earlier difficulties with the IBM-built machines, including a breakdown that caused a last-minute postponement of the first shuttle flight in 1981.

Aware of the machines' fickle past, the controllers promptly shut down the No. 3 computer on Columbia in order to keep it as a fail-safe reserve and relegated No. 4 to managing the vehicle's environmental systems. The fifth computer was on standby. Later, when he was safely on the ground, Young confessed: "When the first one went, my knees shook. When the second went, I turned to jelly." Eventually, Mission Control was able to command No. 2 back into action, although its performance was erratic. No. 1 remained dead for the rest of the flight.

The situation was never life-threatening, since a computer was always available to take charge of the ship. Still, the controllers decided to wave off a landing for several orbits while hundreds of engineers in Houston pored over data in an effort to discover the cause of the failures. The controllers were afraid that the difficulty, whatever it was, would spread through the system and bring down all the ship's computers. Without a computer, even a John Young probably would not have been able to take Columbia safely out of orbit because of the complex sequence of rocket firings needed to control the craft's fiery plunge through the atmosphere.

At one point during the crisis, Young, who had been at the helm for 8 1/2 hours without a break, retired for a nap. As the shuttle program boss, Air Force Lieut. General James Abrahamson, later explained, "There's an old rule among test pilots: when there is a problem, then just slow down and back out."

While Young's copilot, Air Force Major Brewster Shaw, took charge, one of three inertial measuring units, which sense any changes in the spacecraft's speed or direction, mysteriously broke down. In addition, the laws of celestial mechanics added a political problem. Each extra swing around the earth changed Columbia's path. As a result, when the ship swooped out of its last orbit, instead of coming in south of Australia and over the western Pacific, it passed only 80 miles above eastern Siberia in the militarily sensitive area of the Sakhalin Peninsula where Soviet aircraft shot down a South Korean jet last September. Never before had a manned American spacecraft flown so low over Soviet territory; happily for NASA, there were no grumbles from the Kremlin.

The final electronic indignity came at the end of Young's textbook landing. As the orbiter's nose thudded to rest on its front landing gear, the No. 2 computer shut down again. The following day NASA announced it would not sanction the next shuttle flight, scheduled for Jan. 30, until the computer difficulties are resolved.

These new headaches demonstrated once again that the shuttle is still very much an experimental vehicle. Even so, NASA could take pride in the debut of Spacelab and the new breed of payload specialists--scientists from outside the regular astronaut corps, including one West German researcher--who managed its heavy load of 72 experiments. The space agency noted that more than 90% of the studies had been completed. If the scientific data transmitted from orbit in just a single burst were lined up as small, text-size electronic symbols, one official calculated, they would extend from the earth to the moon. After preliminary analysis, Space-lab's international team of scientists, from Europe, the U.S., Canada and Japan, were able to point to a number of important findings, including new insights into the body's reaction to weightlessness, a greater knowledge of the composition of the earth's atmosphere and invaluable experience in growing high-quality silicon crystals in microgravity.

The scientists had high praise for the ingenuity shown by the men in orbit, like Mission Specialist Robert Parker, whose deft use of a sleeping bag provided a cover of darkness while he reloaded a jammed spool of film. Said one Houston observer, University of Naples Physicist Luigi Napolitano: "You know, without those guys, the mission would have been a failure on the first day." The astronauts also found time to clown for the TV cameras and take telephone calls from President Reagan and West German Chancellor Helmut Kohl. But some problems simply had to be endured, like the accumulation of hydrogen gas in their water supply, which caused annoying flatulence. Joked Young: "As long as nobody lights any cigarettes, we're all right."

Young and Shaw left for Houston after Columbia's landing to rejoin their families, but the flight was not over for the other four crewmen. They were driven off to NASA's Dryden Flight Research Facility at Edwards for a continuation of the rigorous biomedical tests, including highspeed whirls in a centrifuge, which had begun on the ground and continued in orbit. These are designed not only to discover ways of coping with space sickness but also to learn whether any significant physiological changes occurred after ten days of weightlessness. Until these examinations are finished this Thursday, the guinea pig quartet must remain in isolation. They can take comfort in the thought that their dedication is bringing the day closer when ordinary mortals will follow the current space voyagers on the way to the stars. Assuming, of course, that NASA gets those balky computers to behave themselves. --By Frederic Golden. Reported by Benjamin W. Cate/Edwards Air Force Base and Jerry Hannifin/Houston

With reporting by Benjamin W. Cate, Jerry Hannifin This file is automatically generated by a robot program, so viewer discretion is required.