Since NASA's early days, periods in space have been a strange and mysterious topic for engineers.

Countless things go into planning a launch and until Sally Ride became the first American woman in space in 1983, tampons and sanitary napkins were never part of that process. 

After wanting to send an overly generous supply (100 tampons for a one week mission) to space for Ride's first mission, it was clear the engineers didn't have a clue. And they weren't the only ones.

NASA's medical staff weren't sure how microgravity would affect menstruation - what exactly would happen if you had your period in space? Would the blood flow like it should, or would it flow back up into the uterus and ultimately cause health problems?

Turns out menstruating in space is not much different than it is on Earth. Women have been living and working in space for decades now, and with no issues.

But here's the problem: all available data on periods in space pertain to short-duration missions.

Researchers are now wondering what's going to happen when astronauts embark on longer missions, like those to Mars and beyond. 

Waste disposal systems onboard the ISS are not all designed to handle menstrual blood, as the toilet system is connected to the water reclamation system (which recycles urine into drinking water).

Personal hygiene is less than ideal in space due to limited shower facilities and water supplies, so menstruating during spaceflight is not as practical as it in on Earth.

As a result, more and more astronauts are turning to oral contraceptives to skip their periods altogether during both spaceflight and training, a new paper in the journal Microgravity reports.

The most common form of suppression is an oral progesterone pill (or simply, 'the pill').

The second most popular option is an IUD (intrauterine device), which is inserted into the uterus by a doctor and can safely last for three to five years. But the ability to suppress a woman's period greatly depends on the type of IUD used. There are two types of IUDs: copper and hormonal, with the latter being more effective. 

Subdermal implants are another option, and are safe to use for up to three years.

Finally, we come to injections: specifically the depo shot. Depo-Provera is a hormone injection similar to progesterone. It must be administered once every 12 weeks, and can be safely used for two to three years.   

We spoke with Kristin Jackson, a Florida-based physician specialising in obstetrics and gynecology about the current options for suppressing menstruation. According to Jackson, the best methods for suppression were either the pill or the IUD. 

"It's completely safe for women to skip their periods," she said.

"A lot of women have difficult periods, and there's no medical reason why a woman has to menstruate every month."

She went on to say that some methods were better than others.

"It's important to note than none of these methods are guaranteed to suppress all periods," she explained.

"Every woman is different, but some methods are more reliable than others."

The most reliable methods aren't always the safest as she points out with the depo shot.

"We closely monitor patients who are on the shot, as one of the side effects is bone loss," she said.

"When you're living in a microgravity environment, bone loss is already an issue, so the shot would not be beneficial for astronauts."

Author of the new paper, Varsha Jain, from the Centre of Human and Aerospace Physiological Sciences (CHAPS) at King's College London, agrees.

"Studies of women in the military have shown that many would like to suppress their menstrual flow during deployment, so it's not a stretch to assume astronauts want to do the same," she explains in a press release.

Jain and her team point out another concern: cargo space. Hauling a three-year supply of birth control pills into space isn't exactly practical.  

"A three-year exploration class mission is predicted to require approximately 1,100 pills, whose packaging would add mass and disposal requirements for the flight," they point out.

But there are reports of bone loss even with the pill, so opting for an IUD or an implant might be an astronaut's best bet.

They would remove the upmass issue, could be implanted prior to the mission, and would not have to be replaced until after the astronaut returned to Earth. 

Further study is needed to better understand the effects of hormones and bone loss in microgravity. But one thing's for sure, we'd better figure it out before we colonise a whole new planet.