On the International Space Station, mouse sperm lives for over six years and produces healthy space newborns.

The report, which was published in the journal Science Advances on Friday, reveals a team of Japanese investigators’ space sperm tests, which were done to better understand the lengthy effects of cosmic radiation on mammalian sperm.

Radiation exposure had no effect on freeze-dried sperm that had been preserved on the station for nearly 2,000 days.

“There were no changes between space puppies and ground control puppies, and their next generation had no anomalies,” the team stated.