A photo of a newspaper headline suddenly went viral on Twitter, stating that "Mars Missions May Be All Female To Avoid Astronauts Having Sex During 1.5-Year Mission." The implication was for readers to laugh at the headline, as it's obviously possible that female astronauts could have sex with one another without any men around during such a long mission.
The headline was posted to Twitter on Wednesday by British singer/songwriter Grace Petrie, and by the end of the day had been retweeted over 10,000 times and liked nearly 49,000 times. A counter within the image on the tweet shows that the story itself had been shared 32,000 times.
This isn't quite fake news, as a story with that headline is real, and from an actual newspaper. It ran in the Express Tribune, an English-language newspaper in Pakistan, albeit on September 29, 2017, more than a year before the tweet spread. The attached photo is of four female American astronauts, although none of them have been announced as part of an all-female crew headed to Mars.
That headline, though, is both misleading and based on an extremely thin premise. The article, which lists "News Desk" as a byline, attributes the all-female crew notion to a NASA "secret report," which was mentioned in a speech at a science conference in London by Helen Sharman, an astronaut who in 1991 became the first British person in space.
However, according to the Express Tribune, Sharman said in that speech that the report was filed "some years ago," was never released, and that she herself has never actually seen it. Even if the report exists, if it was filed a long time ago there's no indication that such an idea is still part of NASA's thinking. And besides, the article is a Pakistani newspaper quoting a British astronaut about the long-ago gender integration policies of the American space program. (The Daily Mail appears to have reported first on Sharman's speech, with other outlets picking up the story back in 2017.)Furthermore, the newspaper story at first states that the reason for all-female crews would be that "women work better as a team, and are less likely than men to fight over who is the leader." Only lower down are there any references to pregnancy, or "impure thoughts."
Science writer Mary Roach's 2010 book Packing for Mars: The Curious Science of Life in the Void, devoted an entire chapter to the subject of sex in space, as well as the sexual ethics of space missions. Roach was unable to confirm any historical instances of astronauts having copulated aboard space shuttles or stations.
At any rate, as of 2015, NASA's plans didn't include a manned mission to Mars until sometime in the 2030s, so the space agency will have plenty of time until then to figure out the gender makeup of the crew. But since NASA has been sending mixed-gender crews to space since the early 1980s, it's extremely unlikely that the "all-female crew" notion is still in play.