Stephanie Moore, who had watched her father on television for two days, said she felt better today after talking to him.

Her dad is Jesse W. Moore, the National Aeronautics and Space Administration's associate administrator for space flight.

Stephanie, 18, had watched her father tell the world Tuesday that there was no evidence that the crew of the Challenger space shuttle had survived the worst disaster in the agency's history.

Moore was the model professional performing in a difficult situation -- concerned, controlled, his emotions solidly in check.

"I could tell he was holding back," his daughter said, adding how relieved she was when she finally spoke with him this afternoon on the phone for the first time since the mishap.

"He broke down and started to cry on the phone," she said. "He said everything seemed perfect before the launch. If anybody hadn't thought everything was perfect, they wouldn't have gone ahead."

Moore said she appreciated his brief show of emotion.

"His work is everything to him," she said by telephone from the family home in Vienna, Va. "The shuttle has been a part of our family life. It's been like a brother or sister to us. When it blew up, it was like a member of the family had died."

Moore, 46, is a well-regarded professional engineer who worked his way through NASA ranks to attain his present position 18 months ago.

He is compact, with thinning light brown hair and a contained manner. He is respected for his technical knowledge of spacecraft and his ability to communicate with the bureaucracy.

"He is a very temperate, measured person who asks very sharp and pointed questions," said Charles Redmond, a longtime NASA associate.

A transitional figure in the space agency, Moore is a native of Columbia, S.C., who earned bachelor's and master's degrees in engineering at the University of South Carolina.

He went to work at NASA's Jet Propulsion Laboratory in Pasadena, Calif., in 1966, a time when the names of astronauts were household words and even the names of some NASA executives were prominent.

Those days are long gone, and the names of those aboard Challenger were unknown to most Americans when Moore ordered liftoff Tuesday.

"All of the people involved in this program, to my knowledge, felt the Challenger was quite ready to go," he said yesterday. "And I made the decision, along with the recommendations from the teams supporting me, that we launch."

Four hours after liftoff, it fell to Moore to deliver the agency's official announcement that six astronauts and a schoolteacher passenger were presumed dead.

"At 11:40 a.m. this morning, the space program experienced a national tragedy with the explosion of the space shuttle Challenger, approximately a minute and a half after launch from here at the Kennedy Space Center," he said solemnly.

"I regret that I have to report, that based on very preliminary searches of the ocean where the Challenger impacted this morning . . . have not revealed any evidence that the crew of Challenger survived."

Moore has been involved in meetings almost continuously since then. He has named an interim board, composed chiefly of NASA executives, to investigate what happen. Today, he said several teams are examining every aspect of the flight.

"Our objective is to precisely find out what happened . . . everybody has a high degree of confidence that we will be able to find it," he added