Earth has been the birthplace for every human in history, but that may change if our civilization expands further into the solar system.
To assess the possibility of future space-born babies, scientists exposed frozen human sperm samples to microgravity conditions to see if a space-like environment negatively impacted their viability.
Montserrat Boada, an embryologist at Dexeus Women's Health in Barcelona who led the study, envisions the experiment potentially leading to space-based sperm banks that could enable human procreation beyond our home world.
“In the future, having gametes and embryos stored in a bank outside the Earth will be very important, not only to make human reproduction possible but also to guarantee diversity which is very important for maintaining the species,” Boada told Motherboard in an email.
Boada presented the results of her team’s research on Sunday at the annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Vienna, Austria.
Sperm cells are extremely sensitive to radiation, which is why some studies predict that male astronauts may experience lower sperm production and motility due to higher radiation doses in the space environment. But there’s uncertainty about the effect of the microgravity environment itself on male fertility.
To help inform that question, Boada and her colleagues collected frozen sperm samples from 10 donors and flew them on a special aerobatic aircraft that can simulate microgravity in short bursts. The plane completed 20 maneuvers, each of which exposed the samples to about eight seconds of space-like conditions.
When the researchers compared the flight samples to controls that remained on the ground, they observed no significant difference between sperm concentration, motility, or DNA fragmentation rate. Tests involving five samples of unfrozen fresh sperm offered similar results, suggesting that microgravity does not pose a major threat to male fertility over short periods.
The findings may be encouraging for anyone eager to start popping out extraterrestrial infants, but Boada cautions that it is a “preliminary study.”
“We know that the best option will be to perform the experiment on the Space Station or using real spaceflights, but access is highly limited,” Boada explained. “This is only the first step of a big project and more research is required.”
To that point, she hopes to follow up the research with longer experiments that take place in orbit, similar to NASA’s Micro-11 project, a study involving human and bull sperm that is currently being conducted on the International Space Station.
“Different platforms are being taken into consideration to try to find longer periods of microgravity for a better evaluation of the possible effects of microgravity on human gametes,” she said. “We are also thinking of going further and evaluating the effects of microgravity not only on human sperm samples, but also on oocytes and embryos.”