After nine months in space, mouse sperm has yielded healthy mice, Japanese scientists say. The freeze-dried sperm samples were launched in 2013 to the International Space Station and returned to Earth in 2014. The intense radiation of space caused slight DNA damage to the sperm. Yet, following in vitro fertilization on the ground, healthy offspring with normal fertility of their own resulted. The researchers say it's a step toward reproducing other mammals, even humans, using space-preserved sperm, the AP reports. They envision missions lasting years or even generations, during which assisted reproductive technology might be used. The findings were published in the Proceedings of the National Academy of Sciences.
Previous developmental studies in space have involved, among other things, fish and amphibians. Mammals are more difficult to maintain and handle in space, and so testing, by comparison, has been limited. More extensive testing on sperm preservation is needed in space, according to the researchers. Besides long-term space crews and societies, the researchers see other reasons for saving sperm in space, including in the event of disasters on Earth. The moon would be ideal for underground sperm storage, they noted, in particular lunar lava tubes because of "their very low temperatures, protection from space radiation by thick bedrock layers, and complete isolation from any disasters on Earth."