Kranz says that it was under Holloway - who was the chief of flight directors before he became program manager - that Dittemore learned the leadership skills needed to be promoted in 1992 into the shuttle program administration. In 1999, Dittemore was appointed to lead the program when Holloway left to lead the space station effort.

"You have to have an incredibly solid technical background, you have to be a team builder at the same time as a team member, you have to have superior judgment," said Kranz. "And you need integrity. The team won't follow you unless you're a whole person, knowing the difference between right and wrong, and selecting a path."

Colleagues say Dittemore's strengths as program director have carried into his public briefings, where he's been forthright and even blunt without sounding defensive. At times, the briefings have resembled college seminars, with Dittemore acting the patient professor, speaking to reporters with a high level of detail, refusing to condescend.

Even as Dittemore has endured scrutiny, some of his employees chafe at the suggestion that he and other supervisors might have overlooked a fatal flaw in the shuttle, such as the thermal tiles that may have been damaged by a chunk of insulation that broke off from the spacecraft's external tank during launch.

"The managers who deal with safety are responsible people. They don't just shrug something off for whatever reason. They make decisions based on good data and judgment," said Gorman Prince Jr., who monitors safety in the main propulsion system.

Added engineer William Arsenaux, "I've always known Ron to do the right thing, the right way. He's exceptional at that, and making other people feel it's important to do the right thing."

In demeanor, Dittemore melds well with the low-key ethic of the space center campus, where engineers in short-sleeve shirts and nondesigner ties carry blueprints along tree-lined paths, looking as if they might have stepped from the 1950s. He's serious, Prince said, "but a little humor comes through - he's not stone-faced."

But even his mentor, Holloway, knows little of Dittemore's life outside work. Dittemore's two children are in college and graduate school. His son, who called his father immediately after the disaster, is studying to become a flight director.

Professional as he may be, NASA leaders say it shouldn't come as a surprise to see Dittemore betraying his feelings in the briefings. For many at NASA, they say, emotion lies just below the surface, because all are constantly aware of the personal stakes of space exploration and prepared at any moment to suffer disaster.

Kranz recalled what it felt like to be at the space center at the time of the first space disaster, the capsule fire aboard Apollo 1 that killed three astronauts in 1967. Those involved, he said, relied on "the inner strength that comes from our deep conviction in this work" and wrote up a proclamation for themselves, to "recognize that what matters is not trying and failing, but that in trying, we gave our best effort."

Dittemore said yesterday that he's been trying to do just that, seeking solace by reading e-mail late at night from all around the country, realizing that he has the support of its people.

"A wise person told me a long time ago that true character is revealed when you come face to face with reality and adversity," Dittemore said. "Certainly, the last few days have been a real challenge to us personally."