Scientists prove that a frozen mouse sperm, flying around the ISS for nine months, can make babies. The frozen sperm had temperatures of -139° Fahrenheit (-95° Celsius).

At an altitude of 250 miles, radiation is more than 100 times stronger than on Earth. So, because of this reason, scientists from the University of Yamanashi wanted to find out if a protracted exposure would affect fertility or health of any progeny. They want to know if humans that will spend years in space habitats can use frozen sperm and eggs up there.

If humans ever want to live permanently in space, they will need to make sure they and any farm of animals they bring with them can reproduce, said study senior author Teruhiko Wakayama, a reproductive biologist at the University of Yamanashi in Kofu, Japan, and his colleagues.

The space pups grew into healthy adult mice. Credit: National Academy of Sciences.

Was the sperm damaged?

However, researchers found evidence that the space-preserved sperm did experience slightly more DNA damage than Earth-preserved samples.

The average daily dose of 0.5mSv from the cosmic rays is enough to damage the DNA code inside living cells, including sperm.

Microgravity also does strange things to sperm. But fertilization and birth rates were similar to healthy “ground control” mice.

In 1988, a similar experiment occurred, as German researchers sent a sample of bull semen into orbit on a rocket and discovered that sperm was able to swim much faster in low gravity, although it was not clear whether this gave a fertility advantage.

Other experiments are underway on the International Space Station. NASA is primarily interested in the health of the astronauts. The absence of gravity loses the strength of bones and squashes the eyes, thus affecting vision. Previous research on the station has helped prove that good exercise hugely slows the loss of bone. However, the eyeball mystery is still not well understood.