Forty years ago, Russian Valentina Tereshkova became the first woman in space.
But while it was a cause for great celebration in the former USSR, her achievement finally ended the hopes of a secret group of US women - known as Mercury 13 - aiming to claim the title.
Tereshkova (left) was awarded Woman Of The Century
It was to be another 20 years before an American woman, Sally Ride, would make it into space.
"They shut the programme down, and the women were stopped at the final stage of their testing," Martha Akman, author of a book about Mercury 13, told BBC World Service's Everywoman programme.
But the idea of the first woman in space coming from the US had run into trouble well before Valentina Tereshkova's mission in 1963.
The women began their testing in 1960 under Randy Lovelace, Nasa's head of life sciences, and they took the same tests as the Project Mercury men.
"As they were to begin the final phase of their testing, they needed to use special equipment that the US Navy had," Ms Akman explained.
"At that point, the Navy said: 'Before you can use this equipment, we need the official green light from Nasa.'
"It was at that point that Nasa took a look at the project and saw it as Randy Lovelace's independent experiment, and not something that Nasa wanted to officially sanction."
But Nasa's reluctance to endorse the project was but one of a number of obstacles to the mission's success that eventually proved insurmountable.
In part, Ms Akman said, they were restricted by prejudice both within Nasa and also other parts of the scientific community.
Gagarin's flight forced Nasa to rethink its mission plan
"The environment here really did suggest that women were thought of as weaker, as less intelligent, as not able to handle the complicated skill that would be required in spaceflight," she stressed.
"That was perhaps their largest hurdle."
Unlike their male counterparts - all of whom were test pilots flying with the full backing of the military - the Mercury 13 women were ordinary civilians.
This raised another problem - they had to get time off from their jobs.
"These women had to approach their bosses and say: 'I have to be away for a while - I can't exactly tell you why, I can't exactly tell you where I'm going,' and some of them lost their jobs," Ms Akman said.
One of the astronauts, Mary Sloane, even lost her marriage to her pilot husband after he became jealous of her involvement in the space project.
"He saw it as too grand, as something more appropriate for a man," Ms Akman said.
"When she returned from testing in New Mexico, she was met at the airport with divorce papers."
As time went on, circumstances conspired against them.
When Yuri Gagarin became the first man in space in 1961, it signalled a shift in priorities in space missions that severely crippled the hopes of the Mercury 13.
"After the United States lost, as it were, the space race to the Soviets when Yuri Gagarin was launched into orbit, President John Kennedy set his sights on landing a man on the Moon," Ms Akman said.
The Mercury 13 women took their appeal to Lyndon Johnson
"He thought that that was a bigger prize than the space race, and a way for the United States to assert Cold War supremacy.
"Women were viewed as complicating things and being unnecessary."
Finally, Valentina Tereshkova made her own piece of history - and Mercury 13 was doomed.
"While the US certainly wanted to launch the first dog into space, the first chimpanzee into space, and the first man into space, they saw launching a woman as not that important - and actually called the orbiting of Valentina Tereshkova as nothing more than a stunt."
Ironically, however, in physical tests the women had scored equal with men, while in psychological ones they actually outperformed them.
"After the testing was cancelled, the women protested, saying they hadn't been given a chance," Ms Akman said.
"They then shifted the focus from a medical one to a political question and appealed to the White House and eventually Vice-President Lyndon Johnson, who was head of the Space Council at the time."
But the protest cut no ice, and the Mercury 13 project was dead.
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Because the mission was so secret, only now are people finding out the details about the Mercury 13 story.
Ms Akman said that in modern times people struggled to believe the story was true, at least in part because the 1960s was generally a time of liberation for women.
"They're amazed at the depth of the resistance to women in space - it seems like some sort of curious historical footnote," she said.
"When we talk about it a little bit more, they're angered that it happened, and really quite mystified why this story hasn't been better known."