The International Space Station can sometimes seem like a menagerie, housing (on different occasions) everything from frogs to worms, crickets, mollusks, butterflies, and even quail. This past summer, 36 animals hitched a ride back on the final flight of the space shuttle - if you don't count the millions of microbes or the swarm of fruit flies, and do count the four humans strapped into the orbiter seats. Even the Iranian Space Agency is dabbling in the zoological, recently revealing that a few months ago they tried to send a live monkey into space and return him to Earth. Sadly, the mission failed.
NASA's animal research policies have come a long way since its days of shooting monkeys into space on brand new, failure-prone launch vehicles. Back then the agency mostly relied on federal law, such as the 1966 Federal Animal Welfare Act, to govern its animal care, until it started to develop more specialized policies in the 1980s. Finally in 1996, it codified a formal rule called the NASA Principles for Ethical Care and Use of Animals. Even more recently, Alex Dunlap, NASA's chief veterinarian, and others drew up an agreement for use on the station; the International Animal Welfare Agreement for Space Borne Research establishes "a base line level of animal care and use in space that all countries could agree on."
With the shuttle retired, American research animals will now be delivered to the space station on European, Russian or Japanese launch vehicles, or perhaps by one of the commercial vehicles under development. And once they arrive, they "could be in the [Japanese Experiment Module] with a Russian crew member, with an American payload. How do you determine whose laws and which country's regulations to use?" says Dunlap, "We basically compiled all the animal welfare laws of all the countries. Some of them are more restrictive, some less restrictive. A lot of it was based on U.S. law."
NASA's use of animal astronauts has changed along with the culture, according to Dunlap. "We've become more compassionate with time, more aware of seeing and making sure that animals get humanely treated." The agency is unlikely ever to return to the days of flying monkeys and chimpanzees. Other than humans, mice are the highest-order animal currently being sent into space. They provide the best balance of sample size (more tissue and bone structure to study) and cage logistics: their small cages are easier to store in a cramped cabin and to provide with ample air circulation.
The mice brought back this summer on Atlantis were part of a medical study by pharmaceutical company Amgen that uses weightlessness to look at bone loss, which is worsened by the absence of gravitational stress on the skeleton. Most animal research in space is geared toward using analogous animal physiology to extrapolate the effects of microgravity on astronaut health. Amgen also hopes to use the mouse study to improve its osteoporosis drugs used on Earth.
Animals can spend months living in space before returning to Earth for analysis. Most are tucked away in experiment racks that are stowed like drawers. The crew only has to check on the animals once a day to make sure they're healthy. But if the animals become sick in orbit, there's little the crew members can do. "We have looked into trying to fly veterinary kits to treat animals," says Dunlap. "But it just becomes problematic, because if you have syringes and needles that you would use to treat an animal, then the safety folks get concerned. They don't want a crew member getting stuck or bitten."
That's why most of the veterinary work Dunlap and his colleagues do is on the ground. Like human crewmembers, space-bound animals are selected for their youth and health, and their ability to tolerate the rigors of spaceflight. They're also carefully screened pre-flight for pathogens that could harm them or the people onboard.
Not all space animals are used for research. Some, like the two spiders that also came back on the last shuttle flight, were launched into orbit as part of an educational program for students. Gladys and Esmerelda, both golden orb spiders, were videotaped building webs and catching flies in microgravity, and the footage was beamed down to elementary school classrooms all over the United States. The students then compared the spiders' actual behavior to pre-flight hypotheses about how they might act, based on how spiders behave on Earth.
Only Gladys survived the return trip on Atlantis, after which the spider was discovered to be male, not female, and renamed Gladstone by his school chums. Some animals, like Gladstone, are cared for and observed after their return home. But for the most part, returning animal test subjects are immediately dissected so that researchers can study in detail how spaceflight has affected their bodies.
"The mice that came back, nothing was wasted," says the space station's Deputy Program Scientist Tara Ruttley of a similar months-long mouse study. "Every single component was used for gaining knowledge, gaining understanding of what happens on long-duration space flight." Their sacrifice will contribute to an understanding of how bone loss works and what can be done to prevent it. And in their brief lives as astro-mice, they experienced a journey few earthbound creatures ever will.