Fourteen years ago, a rookie shuttle pilot named Michael J. McCulley guided Atlantis to a flawless landing, becoming one of America's astronaut heroes. Ronald D. Dittemore was the flight manager, the behind-the-scenes coordinator who was crucial to the mission's success.

The Columbia disaster brought the two men together again -- but their roles as two of the top officials overseeing the mission are somewhat reversed.

This time it is Dittemore, now NASA's manager of the space shuttle program, who is in the public eye, calmly fielding question after question from the press at many of the agency's daily briefings. McCulley, meanwhile, plays a less visible but no less involved role as chief operating officer of United Space Alliance, a joint venture of Lockheed Martin Corp. and Boeing Co. that is responsible for managing the day-to-day operations of the shuttle fleet.

It is the venture's 10,000 employees, not the government, who take the shuttles and get them ready to fly, replacing damaged heat-resistant tiles on the surface of the aircraft and otherwise servicing them. The contractor also mates the fuel tank and solid rocket boosters with the shuttle. And it conducts the final inspection of the ships before they climb into space.

The past few days, McCulley said, have been a blur of technical briefings and discussions over sticky business issues, such as how the company should bill for overtime for the contractors who have pulled extra duty the past few days. He's also taken on the responsibility for the emotional well-being of his employees, bringing in grief counselors and personally trying to have a meaningful "How are you doing?" conversation with everyone he runs into. But it's not the busy times that bother him. It's when things get quiet.

"Sometimes when you find yourself able to sit down, you think, 'We killed seven people, and you're not supposed to do that.' All of us in the program regardless of where we are and what we are doing feel responsible at one level or another," he said.

McCulley reports to United Space president and chief executive Russell D. Turner, who in turn reports to executives at Lockheed Martin and Boeing. McCulley is the hands-on guy, walking the floors of the processing facilities in Florida or at Mission Control here, while Turner concentrates more on financials and strategic planning.

McCulley, 59, knew all the astronauts but was especially close to Kalpana Chawla, whom he calls "K.C." They met a few years ago, when she was still waiting for her turn in space. At the time, she was working at the astronaut office managing the flight crew equipment, and McCulley was deploying new staff there. He has been so distraught since the tragedy that earlier this week he left his truck lights on and the battery went dead.

"I haven't done that my whole life," said McCulley, who like many astronauts is known for being almost obsessively meticulous.

Yesterday, during one of those quiet times, McCulley went back in his files and pulled out a statement he made before Congress in September 2001. He warned lawmakers that cuts in NASA's budget could lead to safety problems: "I am more pessimistic today than I have been in the 17 years I have been doing this. . . . The ice is getting thinner under our feet as we move towards the middle of this lake."

He said in an interview this week that he still stands by those statements but that he strongly believes that NASA's budget woes did not contribute to Columbia's fate -- that despite being several decades old, the shuttle was in excellent condition after being retrofitted with a number of enhancements from 1999 to 2000. He declined to comment more specifically on the investigation into what went wrong aboard Columbia.

"Something happened we didn't anticipate," McCulley said.

McCulley was born in San Diego but grew up on his grandparents' farm in Livingston, Tex. His mother moved the family there shortly after her husband died, when McCulley was 9. Upon graduation from high school, he enlisted in the U.S. Navy and served stints aboard three submarines. He entered Purdue University in 1965 and left with bachelor's and master's degrees in metallurgical engineering. It was there that he was inspired to fly by stories about astronaut Neil Armstrong, another Purdue alumnus.

He rejoined the Navy, serving first as a pilot and then as a test pilot, and was selected to go to NASA in May 1984, serving in a variety of technical jobs -- as the weather coordinator for the astronaut office, as the leader of the astronaut support team -- before being called on to fly Atlantis.

"The thing that excites me the most is to think about looking out and being able to see a round horizon . . . being able to see much of the world," McCulley said a few days before he was to go up in Atlantis in 1989.

He said he still vividly remembers the sights, such as a volcano erupting in Japan, a rice field burning in Louisiana and ships' wakes all across the oceans of the world. All the world's cities, he said, looked similar, and they were "all gray." McCulley had the opportunity to film what he saw with a camera the crew had brought on board especially for the Imax movie "The Blue Planet."

The Atlantis mission McCulley flew was characterized at the time as the most sophisticated yet. The crew was charged with carrying and deploying a $1.4 billion probe called Galileo. It had atomic power cells, which made environmentalists nervous about what might happen if something should go wrong.

And all throughout the mission it seemed as if something might.

The initial launch date was delayed because of a faulty engine-control unit. Then it was delayed again because of rain. The day the shuttle was supposed to land was windy -- so windy, with gusts up to 23 mph on the Mojave Desert, that Dittemore initially considered asking the astronauts to stay up one more day. Instead, the team got a brief reprieve from the weather that allowed them to land three hours ahead of their originally scheduled time.

In the end, the mission went off nearly perfectly -- one of the best NASA had ever run.

McCulley retired from the agency shortly thereafter, becoming part of an army of NASA employees who go back and forth between public service and private industry.

He was hired by Lockheed Martin Space Operations in 1990 and served as the deputy launch site director for the Kennedy Space Center, where he was made director in 1995. When United Space was formed in 1996, he was asked to lead efforts to merge the NASA and private contracting teams responsible for processing and maintaining the shuttles. He was named chief operating officer in November 1999.

Just a few weeks ago, McCulley remembers, he was joking to some NASA officials about how challenging being in management had become and whether he could go back to doing something simpler -- like being a shuttle pilot. McCulley, still a muscular man who jogs several miles each morning, says there's no question he'd be thrilled to go up in the space shuttle again despite what happened Saturday.

He says he knew and accepted -- just as the Columbia crew knew and accepted -- that there was no escape pod, no Plan B, should something go wrong. He remembers that day 14 years ago when he sat down with his two eldest daughters (he has two more daughters and a son) before his flight and told them there was a possibility he might not come back.

"If this thing doesn't go right, I will go away doing what I was happy doing," he said.

It is something, McCulley said, he tries to remind himself of when he thinks about his colleagues aboard Columbia.

Michael J. McCulley, United Space Alliance executive and former shuttle pilot, after a practice run of T-38 fighter jets in 1989.Commander Donald E. Williams and the crew of the space shuttle Atlantis speak to the press after training flights for the launch of the shuttle in 1989. The crew, from left: Shannon W. Lucid, Ellen S. Baker, Michael J. McCulley and Costa Rican-born Franklin R. Chang-Diaz. MICHAEL J. MCCULLEY