Challenger's Agony and Ecstasy

By Natalie Angier

It was what old NASA hands affectionately call an Eddie Air Force Base kind of day: blue sky, visibility of 45 miles, perfect for a landing. And as the space shuttle Challenger touched down last week on the runway at Edwards Air Force Base, Calif., in 95DEG heat, kicking up petticoats of dust, a flight that had begun in near disaster ended in triumph. Declared Mission Manager Roy Lester: "Even with a rough start, we achieved excellent science."

The first big glitch occurred on July 12, when a computer detected contamination in Challenger's hydrogen fuel and aborted the launch 3 sec. before takeoff. The 112-ton spacecraft blasted off 17 days later, but 5 min. 15 sec. into the flight, a monitoring device reported that one of the three main engines seemed to be heating up to a dangerous 1,950 DEGF. That sensor alerted the onboard computer, and for the first time in the 24-year history of the U.S. manned space, an engine was shut down in flight. But as the craft hobbled bravely heavenward, mission control decided that the seven crew members should proceed with the flight at a stunted orbit of 197 miles above earth (the planned orbit was 242 miles). Challenger carried a $73 million array of sophisticated astronomical and scientific instruments, and researchers hoped that a series of 14 experiments, some painstakingly calculated for the higher orbit, would still work.

Their optimism was soon dashed. On the first day of flight, the astronauts tried to deploy a new instrument-pointing system (IPS), designed in West Germany, that aimed three of the onboard telescopes at celestial objects. The precision of the IPS is equivalent to focusing on a dime two miles away. The $60 million device, however, had bugs in its computer software and would not track properly. There was a brief moment when Astronomer-Astronaut Karl Henize shouted, "Hallelujah, it looks like it's working!" only to watch it wobble off target. Conceded Henize: "That hallelujah was a bit too quick, wasn't it?" Later the astronauts jerry-rigged an arrangement to aim the three solar telescopes toward the sun in time to photograph a spectacular cascade of flares and nuclear eruptions. Four days into the mission, the crew and ground control had the IPS working as well.

To make up for lost time, the crew crammed even more work into their already difficult round-the-clock schedule. An X-ray telescope zoomed in on the distant stellar clusters of Virgo and Centaurus, recording the precise contours of their massive radiation fields. Toward the other end of the electromagnetic spectrum, another telescope, an infrared instrument, mapped the invisible heat of the Milky Way. A small satellite called the plasma diagnostics package was suspended from the ship's giant remote arm to measure "ripples," or the wake that the shuttle causes in the earth's ionosphere. At several points, the shuttle fired its thrusters to poke temporary "holes" in the ionosphere, allowing radio astronomers based around the world to aim their telescopes through the gaps. Indeed, the experiments hummed along so well that NASA decided to extend the mission an extra day.

NASA officials, with their normal tumble of superlatives, deemed the mission a "great success." Said the chief mission scientist, Eugene Urban: "Scientists will be busy for years working with these data." Yet a few gremlins still lurk. Three times in the past year, the launch procedures have resulted in near disaster. And though Discovery waits eagerly on deck, ready for a late August launch, NASA remains way behind schedule. --By Natalie Angier. Reported by Jerry Hannifin/Kennedy Space Center

With reporting by Reported by Jerry Hannifin/Kennedy Space Center