Drugs that are sent into space don’t act any differently than drugs on Earth — that’s the conclusion of a surprising new paper that indicates that radiation and gravity don’t have much have an effect on them.

Scientists tested a number of different medications aboard the International Space Station for a period of 550 days, running the gamut between sleep aids, painkillers, antihistamines, and antidiarrheal drugs, to name a few, and they found there didn’t seem to be any change in the shelf life of the products, according to a UPI report.

While drugs degrade over time, exposure to certain things can accelerate that decline. In space, it was thought that exposure to microgravity and radiation might accelerate their degradation, but scientists at the Center for Space Medicine and Department of Pharmacology at Baylor College of Medicine and Texas found that this was not the case.

Most of the drugs that arrived home from the ISS were expired, but the tests indicated that four of the nine drugs still met U.S. standards, which require that they be viable nine months after they expire.

More research will be needed to see if these medicines are actually safe for a long trip in space — say, a trip to Mars — but it’s an encouraging finding that could have implications for future missions.

The researchers cautioned in a statement that the findings shouldn’t be used to measure the safety or effectiveness of other medicines, as only a small range of medications were tested in this experiment.

The findings were published in the AAPS Journal.