She was the first American woman in space. Then, in her will, Sally Ride blazed another trail…

Astronaut comes out with message posted on her website after dying of pancreatic cancer aged 61

Sally Ride floats weightlessly on the flight deck of Challenger during its second mission in space (PA)

Friends, feminists and former colleagues are mourning Sally Ride, the first American woman to fly in space, who has died at the age of 61 after a 17-month battle with pancreatic cancer.

A pioneer in death as well as life, Dr Ride used her obituary to posthumously "come out" as a lesbian, instructing her family to publish a statement on her website announcing that she would be survived by Tam O'Shaughnessy, "her partner of 27 years".

It was a fitting gesture from a very private woman whose public battle against prejudice began in 1983, when she was first selected to fly on the space shuttle Challenger. Later in life, she ran an eponymous company which aimed, among other things, to help girls learn to about and enjoy science.

Ms Ride's sister, Bear, described Ms O'Shaughnessy as "a member of the family" but said the existence of their relationship was previously kept under wraps to prevent it becoming tabloid fodder during Sally's lifetime. "I hope it makes it easier for kids growing up gay that they know that another one of their heroes was like them," she told the Buzzfeed website.

Dr Ride had an uneasy relationship with fame from the moment she entered the limelight at the age of 32. She had to endure a barrage of highly misogynistic questions at her pre-launch press conference. "Would she be wearing make-up in space?" one reporter asked. "Did she worry about crying on the job if something went wrong?" pondered another.

When a journalist enquired as to whether the US space agency Nasa had issued a special brassiere, she replied tartly: "There's no sag in zero-G!"

Dr Ride, who had a PhD in astrophysics from Stanford University, pointed out that her famous flight was not exactly a world first: the Russian cosmonaut Valentina Tereshkova had became the first woman in space 20 years earlier.

Dr Ride was chosen for the mission solely on merit, and was upset to be considered a novelty. "It is important to me that people don't think I was picked for the flight because I am a woman and it is time for Nasa to send one," she said at the time. "It's too bad this is such a big deal. It's too bad our society isn't further along."

Nonetheless, newspapers devoted endless column inches to Dr Ride's journey and also delved into her relationship with a fellow astronaut, Steve Hawley. They had married in 1982, reputedly decorating their bedroom with a large photograph of astronauts on the Moon, but divorced five years later.

Mr Hawley recalled yesterday how Dr Ride found herself "a very public persona". He said: "It was a role in which she was never fully comfortable. While she never enjoyed being a celebrity, she recognised that it gave her the opportunity to encourage children, particularly young girls, to reach their full potential."

Dr Ride flew twice in Challenger, but her prospects of a third journey into orbit disappeared in 1986, when the shuttle exploded. After leaving Nasa in the late 1980s, she spent several years at Stanford before moving to San Diego and starting Sally Ride Science, a company which provided study materials aimed at helping teachers to "make science and engineering cool again".

"Sally Ride broke barriers with grace and professionalism," said a tribute from Nasa. "The nation has lost one of its finest leaders, teachers and explorers ... She will be missed, but her star will always shine brightly."