On normal mornings, the man responsible for NASA's space shuttle program rises early enough to run five miles before arriving at his desk at the Johnson Space Center by 6:30.

Now, as he carries the weight of disaster, Ron Dittemore's work ethic is his salvation. "The best therapy in this business is to get on with your job," the manager of the shuttle program said.

Appearing at daily news briefings, Dittemore has become the public face of NASA's tragedy, mixing technical phrases -- "debris assessment" and "incident angle" -- with an awe of space and the "amazing machine" that was the Columbia. Hours after the shuttle disintegrated with seven astronauts aboard Saturday morning, Dittemore expressed a vulnerability not commonly associated with managers of vast bureaucracies.

"My thoughts are on seven families, children, spouses, extended family," said the 25-year NASA veteran. "My thoughts are on their grief. My thoughts are on what we missed, what I missed, to allow this to happen."

As investigators turn their attention toward the Columbia's launch and a piece of foam insulation that shredded off the fuel tank, Dittemore's leadership will come under scrutiny. His team reviewed the launch films the day after takeoff and noted the debris, which looked as if it hit the orbiter on the left wing. In their analysis, it was inconsequential.

"He is obviously under a tremendous amount of pressure and stress," said Mark McDaniel, a member of the NASA Advisory Council. "I'm just glad he's been able to hold up these last few days. The space program is his life."

As three inquiries into the disaster have been launched, Dittemore's friends and co-workers said he would rely on his methodical approach to detail and his spiritual side. He is trying to stay busy; at a news briefing yesterday he fought his emotions when he said his hardest times are when he is alone. He lives in a Houston suburb with his wife; their two children attend Brigham Young University.

Dittemore was working in the shuttle program when the Challenger exploded in 1986. "There was a little finger-pointing at NASA, but he didn't want finger-pointing, he wanted facts and resolution," said Dittemore's brother, David, a retired aeronautics engineer in Phoenix.

Dittemore grew up in Spokane, Wash., the son of a master sergeant based at Fairchild Air Force Base. In childhood, he and his brother would race on their bicycles to the fenced-off runways, watching B-52s take off. At Medical Lake High School, Dittemore was captain of the wrestling team and a quarterback. Money was never plentiful; while studying for his degree in aeronautical engineering at the University of Washington, Dittemore lived in a 16-foot trailer behind a gas station two miles from campus.

After receiving a master's degree at Washington, Dittemore worked for an engineering company in Arizona, developing turboprops and turbofans. He was 25 when he joined NASA in 1977 as a space shuttle propulsion systems engineer. During early shuttle flights, he was a propulsion systems flight controller in Mission Control. In 1999, he was named director of the space shuttle program.

Spokane would reappear in his job. One of the astronauts on the Columbia was Michael P. Anderson, who also grew up on Fairchild Air Force Base.

"This is red-hot work," Dittemore exuberantly told a group of college students two years ago. The square-jawed scientist pointed out the miracles that NASA was accomplishing on less than 1 percent of the national budget, with less than a quarter of this 1 percent going to the shuttle program. This, Dittemore noted, was less than worldwide sales of Domino's Pizza.

Staff writer Lois Romano contributed to this report from Houston.

An emotional Ron Dittemore, NASA's space shuttle program director, has become the public face of the Columbia tragedy.