A mouse that was part of an elite team that spent two weeks in microgravity on board China\u2019s Shenzhou-21 spaceship and Tiangong space station has proven there is no conflict between career and motherhood for space-traveling rodents. She gave birth to nine pups and although three of them died soon after, this is considered a normal mortality rate among a species that thrives on large litters. The result is particularly impressive after the mice experienced an unintended interruption to food supplies.<\/p>\n
We\u2019ve been sending animals into space<\/a> since before we went ourselves, since prior to the launch of street dog Laika<\/a>, no one knew if there was some threat beyond the atmosphere that would equal instant death. Even after astronauts had clocked up many months in low-Earth orbit, an ark\u2019s worth of small animals were sent into orbit for research purposes.\u00a0<\/p>\n One of the big remaining questions that needs to be answered before colonizing the Moon or Mars is whether there is any risk to reproduction. As part of the effort to answer that question, the Chinese Academy of Sciences (CAS) sent four mice into space and tried to get them to breed soon after.<\/p>\n “This mission showed that short-term space travel did not impair the reproductive capability of the mouse,” said Professor Wang Hongmei of the CAS in a statement<\/a>. “It also provides invaluable samples for the investigation of how the space environment influences early developmental stages in mammals.”<\/p>\n The moustronauts were launched on October 31 and returned to Earth on November 14. Mice have a gestation period of around 19-21 days, and the pups were born on December 10; those that survived to Christmas were deemed healthy and to be nursing normally.<\/p>\n Just as space agencies carefully screen their astronauts, the CAS put the mice through fitness and balance tests, as well as measuring their susceptibility to motion sickness and persistence in the face of obstacles, before including them on the mission.<\/p>\n Previously, the CAS had released video of the mice in their cage noting<\/a>, \u201cThe mice can be seen taking turns resting in shelter nests inside the facilities and occasionally climbing actively along the cage walls \u2013 appearing lively and well-adapted.\u201d To address the problem of mouse hair and droppings floating unhygienically around the enclosure the cage had an airflow directed towards a sticky surface on its \u201cbottom\u201d.<\/p>\n Observations of the health of both mother and pups will continue, in the hope of identifying any lasting effects from the journey. The short mouse life cycle means that their two-week trip is equivalent to more than a year in space for\u00a0humans<\/a>.\u00a0<\/p>\n Nevertheless, it might be argued that the study doesn\u2019t address the biggest concerns about the effects of space travel on female fertility. Not only did the mouse in question not conceive in microgravity, let alone give birth there, she didn\u2019t fly through or beyond the Van Allen belts, and therefore remained shielded from the highest radiation exposure.\u00a0<\/p>\n Unexpected extra stress was created when impacts from space junk<\/a> delayed the mice\u2019s planned return aboard Shenzhou-20, leaving them with insufficient food supply. Soy milk intended for the human taikonauts was deemed the most suitable supplement<\/a> to their dwindling stocks.<\/p>\n \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/p>\n We have known since 1964, when Valentina Tereshkova and Andriyan Nikolayever \u2013 respectively the first woman and fifth man in space \u2013 had a child, that that spaceflight is not fatal for fertility. Tereshkova gave birth less than a year after her mission, but those short early hops were not necessarily indicative of the effects of longer missions.<\/p>\n Mice were sent into suborbital flights as far back as 1950 and five even orbited the Moon<\/a> in 1972 on the Apollo 17 mission. However, the four survivors of that trip were euthanized on return before they could try to reproduce. In an experiment with parallels to the famous study<\/a> on identical twin astronauts Scott and Mark Kelly, 20 mice were sent to the ISS in 2018 and their health compared<\/a> to twins back home.<\/p>\n The four mice on this mission have been given names that translate as<\/a> “gaze at the sky,” “reach for the Moon,” “chase the clouds” and “follow the dream,\u201d but as far as we can tell the mother\u2019s anonymity has been preserved.<\/p>\n