A mouse-astronaut candidate poses atop a model solar panel. Courtesy of NASA.

A crew of intrepid white mice arrived on board the International Space Station (ISS) this week. The all-female group of twenty rodents is on an important scientific mission. They’ll be involved in rigorous physical endurance testing to better understand the ways in which muscle strength deteriorates in microgravity. This mouse research will help NASA better care for astronauts while in space and when they return to earth. And this won’t be the first important contribution mice have made to space travel.

In fact, animals of all kinds have been essential partners in spaceflight since the U.S. and other countries began launching rockets in the 1940s. The very first species to leave Earth’s gravity was a group of Drosophila fruit flies on board a V-2 rocket from New Mexico. Their well-understood genomes made them the perfect choice to study the mutagenic effects of high-altitude radiation on DNA. Soon afterwards, monkeys, dogs, mice and rabbits, all took rocket rides to pave the way for future human space exploration.

Since no one had ever experienced the severe G-forces of launch and re-entry, nor had floated in microgravity, we understood very little about how human physiology would respond to the effects of spaceflight. The animals that visited space in the 1950s and 1960s were equipped with various types of monitors to measure vital signs to better understand what would happen to blood pressure, respiration, and heart rate once gravity disappeared. They helped make human space exploration a reality.


NASA astronaut Nicole Stott works with the Mice Drawer System (MDS) in the Kibo laboratory of the ISS. Courtesy of NASA.

Mice are excellent partners in space research as they provide a complete picture of interacting physiological systems. Their physiology and genetics are well characterized. Their relatively short life spans mean a mouse spending six months on the ISS is equivalent to a human spending a decade or more there. Using a mouse model, it’s possible to extrapolate long-term exposure in humans via experiments that take only months instead of years. They’re also light and small, which means they don’t take up much valuable payload space. In fact, NASA considers rodent research so important to their overall mission they’ve designed a specialized “Mice Drawer System” to transport and house them on the ISS. The habitat even has a visible-light and infrared camera so that scientists and veterinarians back on Earth can keep a close eye on the rodent teams.

Animal research in space also leads to breakthroughs for people on earth including insights into gravity’s effects on bone destiny loss and the immune system, which has implications for a myriad of diseases including cancer. Mouse research in space has also helped to further our understanding of what microgravity does to the endocrine, vestibular and sensory systems.

Everything scientists will learn from the ‘mousetronauts’ on the current ISS mission is still unknown, but the possibilities are ‘astro’nomical both for future explorers to other planets and for the rest of us earthlings. And we have hundreds of little white mice to thank for that.


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