When Sally Ride, the first American woman to go to space, was preparing for her history-making mission in 1983, NASA engineers were trying to gather the supplies she’d need to take with her. They thought to include tampons, but they had no idea how many women actually use. The mission only lasted a week, and Ride recounts in an oral history that they asked her, “Is 100 the right number?”

“No. That would not be the right number,” she replied.

“They said, ‘Well, we want to be safe.’”

“I said, ‘Well, you can cut that in half with no problem at all.’”

(Also as part of this discussion the engineers, “in their infinite wisdom,” Ride said, designed a makeup kit for the women astronauts.)

Even this silly, bumbling male ignorance of how women’s bodies work was a step up from earlier attitudes about menstruation in space. A 1964 report published by the Woman in Space Program, which gave women aviators the same tests as the Mercury astronauts, emphasized “the potential for the menstrual cycle to alter performance during space flight,” as a review paper notes. There was no reason to believe this—13 of the 19 women tested passed with “no medical reservations,” a 68 percent success rate compared to the men’s 56 percent success rate. Indeed, this suggestion smells more like old-fashioned sexism than actual medical concern; the report goes on to say that “the intricacies of matching a temperamental psychophysiologic human and the complicated machine are many.”

On the actual medical side was the concern about retrograde menstruation—that the lack of gravity in space would cause the blood to flow inward instead of outward. This is a thing that happens sometimes on Earth. Menstrual blood can end up in the abdomen, and this is thought to be the likely cause of endometriosis, a condition that can cause pain and fertility problems. But there’s no evidence that this happens any more in space than it does on the ground.

So menstruating in space is not dangerous. But it can be inconvenient, and some women astronauts prefer just not to bother with it. A new paper published in Microgravity reviews the possible options for period suppression in space, and while training to go to space.

One of the paper’s authors, Varsha Jain, is a visiting researcher at King’s College London and a practicing gynecologist. In November 2015, she gave a training session about menstrual suppression for female astronauts at NASA. For the most part, she said, “The women that I spoke to, for short duration flights, when they went up on shuttle missions, they chose either to suppress or they chose to time their cycles, so they didn’t have to deal with their menstruation in space.”

If they suppressed their periods (which is a totally medically safe thing to do, by the way), they did so using oral contraceptive pills—just skipping the placebo pills typically included to allow a woman to bleed and “mimic a natural cycle,” as the paper puts it.

Jain suggests that long-acting reversible contraception (LARCs), like intrauterine devices and implants could be a better way of doing this (as well as just being the new gold standard of birth control for everyone, anyway). These vary in their ability to suppress menstruation (about 41 percent of women stop having periods after three years with an implant, while a hormonal IUD stops menstruation for 80 percent of women after a year), but they’re long-lasting and require no extra attention after insertion.

“If you think about going into space, pretty much everything that you need you have to take with you,” she says. “Now, if you think about a three-year Mars mission, so we're looking to the future, for three years, you can approximate a daily pill, every single day, it's about 1100 pills. That’s a huge amount of weight, and packaging you have to then dispose of. With the LARC, before you go into space, you know what your bleeding pattern is going to be like, it's inside the human being, so you don't have any additional mass or trash that you have to deal with, and they don’t have to remember the daily pill. Once it's in, it's in.”

LARCs would also be helpful during intense pre-mission training, when astronauts are going on long-haul flights through multiple time zones, and might not want to deal with remembering to take a pill at the same time each day while doing so.

This would require some advance planning, though. “It takes six to nine months for that bleeding pattern to settle down and for the woman to understand what her body is going to be doing,” Jain says. “I would recommend that actually they would have that IUD inserted, or whatever LARC they wanted to use, at least two years beforehand.”

Some astronauts Jain has spoken to told her they have menstruated in space and during training without difficulty. “They felt that their periods were something they didn't want to give up on, and actually they didn’t feel like it impeded their training.”

“Full amenities are available should astronauts choose to menstruate,” the study reads. (Although apparently the United States’ waste-disposal system on the International Space Station is not designed to deal with menstrual blood, so urine containing blood can’t be recycled as it usually would be. Yet another example of NASA not planning for women’s bodily functions.)

As we look forward to possible future years-long missions, and even commercial spaceships, knowing how to care for people’s health will be critical. “I think a lot more research is needed with regards to women’s health in spaceflight,” Jain says. But for now, “the female astronauts need to know what options they have available for them based on the environment in which they're working. I think it comes down to giving optimal clinical care really.”