Frozen sperm samples would remain viable during a space flight, paving the way for a space-based sperm bank, according to Spanish scientists.

The study, presented at the European Society of Human Reproduction and Embryology in Vienna, exposed human sperm samples to microgravity, and analyzed its concentration, motility, vitality, morphology and DNA fragmentation.

Scientists chose to use frozen sperm because radiation can affect the quality and viability of fresh sperm.

After transporting the samples on a small aerobatic training aircraft, researchers found that there was almost no difference between the control sperm on Earth, and the one which had been exposed to microgravity.

"If the number of space missions increases in the coming years, and are of longer duration, it is important to study the effects of long-term human exposure to space in order to face them. It's not unreasonable to start thinking about the possibility of reproduction beyond the Earth,” Dr. Montserrat Boada, from Dexeus Women's Health in Barcelona, said.

The team will now move on to larger sperm samples, longer periods of microgravity, and using fresh rather than frozen sperm, she said.