It has been seven weeks since Barbara Morgan, the alternate for Christa McAuliffe, NASA's teacher in space, watched the shuttle Challenger explode in the Florida sky.

Now, 34-year-old Morgan, the understudy, is on:

"I'm very determined to fly, and I think the opportunity will come," she said yesterday at a press conference at L'Enfant Plaza Hotel. "I think the commission will find the problem, and NASA will fix it."

Morgan, a second grade teacher from McCall, Idaho, and a Phi Beta Kappa graduate of Stanford University, had begun her public duties as the ranking teacher in space. She stepped not onto the shuttle -- last month NASA promised to put a teacher in space when the shuttle program resumes -- but into a whirl of publicity.

And yesterday, with about a dozen other teachers, she announced the formation of the Teacher in Space Education Foundation, a nonprofit organization set up to foster the use of space in teaching, encourage awareness of mathematics and science in the educational community and recognize innovative teachers.

McAuliffe had become accustomed to handling questions about being an ordinary person on an extraordinary journey. Now, Morgan is faced with questions about being an ordinary person on an extraordinarily dangerous journey.

"We definitely knew the risks," she said. "We were told over and over again. Commander [Francis] Scobee [commander of shuttle mission 51L] told us about the risks. He said there will be an accident one day, and it will be catastrophic."

Persistently, she was asked if she and McAuliffe, the nonscientists, were told specifically about risks? "I would say we heard about it at least once a week," she said. "And it wasn't in little flippant remarks. It was straightforward."

The questions continued in the same vein, and Morgan continued firmly in the same vein:

"I know there's still a lot of risk involved," she said. "I'm no fool."

In the midst of criticism from the presidentially appointed commission investigating the shuttle accident as well as from NASA astronauts, Barbara Morgan professes complete confidence in NASA and fervent desire to ride the shuttle. She is a brilliant public relations representative for NASA -- and she knows that's what everyone thinks.

"I don't feel I'm being used at all," she says. "I'm very excited to be participating in this."

There were 112 semifinalists in NASA's Teacher in Space Project, and if they're like Morgan, they are well spoken, intelligent and relentlessly optimistic about the future of NASA and space travel. All are appointed as "space ambassadors," to put out the good word about the future of space to academic and civic groups around the country.

"On the road with Barbara Morgan," she laughs about her role. She also wants to keep up her flight training with reading. "It's like learning a language. You have to keep practicing." She returns to her teaching job in September.

All the "space ambassadors" will be involved in the Teacher in Space Education Foundation.

Since the accident, she has been back to Idaho to see her own students and has coped with her own grief. "It was very, very hard," she says. "But I'm fine. And I miss my friends very much."

Asked if the accident brought her more into the astronaut fraternity, she says firmly, "I felt a part of it the moment I stepped into Johnson Space Center."

She will admit to a wisp of fear on her own part -- "I'll probably be more scared stepping on the shuttle but it won't stop me . . . I've been scared floating down the Amazon River in a dug-out canoe."

But she will confess to no fears about NASA. "Christa was going on the shuttle for education," she says. "I'm going for education. I have complete trust that when NASA is ready to fly I will be ready to fly."

And she won't really respond to criticisms and fears about NASA expressed recently by members of the astronaut corps. "I know those people spent many hours interviewing, and I'll bet more positive things came out than were in the media," she says.

She talks excitedly about students she has met across the country who share her excitement about space. "I wish I could show you the piles of letters -- 'Reach for the stars.' 'Go for it,' " says Morgan. Letters have numbered about 150 a week for the past several weeks, she says.

Morgan echoes McAuliffe in saying that a teacher in space not only demonstrates that space is open to ordinary people but raises the recognition level of teachers. "In all of our training, Christa and I -- I can't tell you how many people came up to me and said, 'My brother's a teacher,' 'My sister's a teacher,' 'My neighbor down the street is a teacher -- you wouldn't believe what he's doing in his classroom.' People are so proud."

If the teacher "space ambassadors" are undaunted by the shuttle disaster, the students appear even more so, according to some teachers.

David Zahren, a teacher-semifinalist from Greenbelt says, "I find young people -- elementary school students -- aren't cognizant of their own mortality. They see the accident a' la 'Star Wars.' It doesn't hit them like adults."

It hit Zahren. He was standing in front of the Orlando Hilton, on his way to the airport after a week in Florida for the 112 teachers, when the Challenger was launched. He -- and the rest of the International Drive traffic -- paused to gaze up contentedly at the shuttle's ascent when everything went wrong.

"It's just an image that keeps coming back," he says. "I see that fireball, I see those contrails . . . You read in books about your heart freezing. It's true. You feel that chill." Stunned, he continued on to the airport. As his plane took off, he remembers, the smoke from the explosion still hung in the air.

A few days later, he was back in the schools, again the ambassador of the good word about space.

"If you're funereal, despondent or hesitant with young people, they become suspicious," Zahren, 36, says. "They have to see that drive. I am a cheerleader of sorts. I don't minimize the risks, but I tell them, 'Someday you're going to walk into BWI or National and buy a ticket to the shuttle, to go to the moon, and you're going to poke your neighbor and say, 'Remember when there was all that excitement about a teacher in space?' "

Says Zahren, who once wanted to join the space program but settled instead on the Peace Corps, "I want to go so badly, I can't wait."