Ask most Americans to name their country's pioneering female astronaut, and they'll probably say Sally Ride, who was the first woman to fly on a space shuttle. But before Sally Ride came the "Mercury 13" - a group of American women who passed the rigorous tests needed to become astronauts, but never made it into space. Mount Holyoke College professor Martha Ackmann explains why in a book called The Mercury 13: The Untold Story of Thirteen American Women and the Dream of Space Flight.

Martha Ackmann got interested in the Mercury 13 back in the late 1990s, after reading that one of America's first male astronauts, John Glenn, was planning a second trip into space.

"And way down in about paragraph eight it said, and 'Jerrie Cobb is a little concerned about this because she never got her first chance to go into space,'" she recalled. "And like everyone else I said, 'Who's Jerrie Cobb? When was she tested? What is this story?' I became very interested and started research then."

Jerrie Cobb set numerous world flight records, and was named 1959 Pilot of the Year by the National Pilots Association. She was one of 19 American women pilots who were secretly tested for astronaut training in 1961. The project was launched by Doctor W. Randolph Lovelace, chairman of the Life Sciences Committee for the National Aeronautics and Space Administration (NASA).

"After he tested John Glenn, Alan Shephard, Wally Schirra, all the Project Mercury astronauts, he asked himself what would happen if we gave these same medical and physical tests to women pilots," she said "He was always a man who was pushing the limits of scientific inquiry. He was also a man who didn't assume as many in the scientific and medical community did, that women were weaker, more fearful, nervous and somehow incompetent intellectually to handle the demands of space flight. He simply didn't buy that."

In fact, Martha Ackmann believes the women who were tested were a daring and adventurous group of pilots, flight instructors and aviation racers.

"They were inspired by the WASPS, the women air force services patrol of World War II," she added. "They often were active in the Civil Air Patrol. And they were just women who were curious about the unknown, that were confident about their abilities. And there were many women like that in 1960 and [19]61."

The oldest was 40-year-old Janey Hart, one of America's early helicopter pilots, a mother of eight, and the wife of Michigan Senator Phil Hart. The youngest was a 22-year-old flight instructor named Wally Funk. Sarah Gorelick, now Sarah Gorelick Ratley, was an electrical engineer from Kansas City, who'd been flying planes since high school. When she heard she was among those to be tested, she jumped at the chance.

"When you're young everything's exciting and a new adventure," she said. "I felt I was going to make it through it, and I wanted to go badly enough I didn't care what they threw at me. I was going to do it."

The women underwent some 75 physical and psychological tests at the Lovelace Medical Foundation in New Mexico.

"One test was pedaling a stationery bike while they were hooked up to all sorts of machines to record their metabolic rates," recalled Ms. Gorelick. "And they had to pedal the bike faster and faster to a metronome while technicians made it seem they were going uphill. And Wally Funk said she asked the technician how long has anyone stayed on this bike, and the technician thought about the one she had just tested and said, '10 minutes,' and Wally gritted her teeth and pedaled and pedaled and hit 11. That just shows you how much she wanted to do well on these tests."

Thirteen of the 19 women who were tested passed, with scores equivalent to the male applicants. But they never made it into the next testing phase, which involved space flight simulation at a U.S. Navy facility in Pensacola, Florida. The Navy refused to allow the test to go forward without NASA's permission, and NASA said it had no interest in pursuing the Lovelace project. The women took their case all the way to then Vice President Lyndon Johnson and to the U.S. Congress, but they got little support.

"Speaking on behalf of NASA were John Glenn and Scott Carpenter," she said. "They had just come back from their extraordinary orbits of the earth. John Glenn, when he was asked, should women be astronauts, said, 'Men go off and fight the wars and fly the planes, and women stay at home. It's a fact of our social order.' Glenn, when I interviewed him, says he was simply describing the way things were in 1962."

Sarah Gorelick had quit her engineering job to take part in the testing. She was bitterly disappointed by the outcome.

"At one point we even felt like we had been defeated in the press, because every time a woman was mentioned, like Jerrie Cobb, they'd give her dimensions," she recalled. "It was very demeaning. I felt we should be recognized not because we were women, but because of what we ourselves could do as individuals or what we could bring to the program."

In 1963, a Russian factory worker named Valentina Tereshkova became the world's first woman in space. Mission specialist Sally Ride was the first American woman in space in 1983. In 1995, Eileen Collins became the first female to pilot a U.S. space shuttle. Martha Ackmann believes the impact of women's rights activists and female military pilots helped change attitudes at NASA. But she says the Mercury 13 also paved the way, and Eileen Collins invited them to attend her launch.

"Watching that shuttle lift off the launch pad and thinking about the dreams they had 40 years before, it was a bittersweet moment," she added. "In fact, Jerrie Cobb got down on the ground as the countdown neared the end and sort of spread her hands around the wet grass. She wanted to feel the ground rumble as the shuttle took off."

Sarah Gorelick was also there, and remembers feeling very proud. "We felt like what we'd done had not been done in vain," she said. "We had laid a base where some woman could climb on our shoulders and go forward. It was a wonderful, exhilarating thing, as though we had been redeemed."

The Mercury 13 have moved on to other accomplishments as aviators, businesswomen and social activists. But Martha Ackmann believes that for all they've done later in life, they haven't been honored enough for what they never got a chance to do.

"I think that's like saying that this little meeting women held in 1848 out at Seneca Falls to discuss the vote, that because the vote didn't happen for women overnight that it wasn't very important," Ms. Ackmann said. "We know that's not true. We know change sometimes takes a long time. So they have simply been forgotten, I hope we remember them now."

One person who does remember is NASA shuttle pilot Eileen Collins. Before blasting off into space in 1995, she said of the Mercury 13, "They gave us a history."