Although scientists gave assurances that experimental animal-astronauts would return home to Earth alive, more than half of the 45 mice (and all of the eight Mongolian gerbils) died during a space mission that launched in April. The 15 newts are doing fine.

Scientists are blaming the low survival rate on equipment failure and "the stresses of space." Launched in separate containers, the animals were allowed to mingle during the flight.

Yet it turns out their deaths had been intended all along.

Lost in Space

Scientists expected the mice, gerbils, geckos, and other creatures to survive the plunge through the Earth's atmosphere; but in order to run tests and get the data they need, researchers had been planning to "humanely euthanize" the animals, Nicole Rayl, project manager for NASA's portion of the mission, told SPACE.com.

The surviving animals (which also included "snails, some plants, and microflora") have been moved from the landing area in Orenburg to Moscow for further testing. "This is the first time that animals have flown in space for so long on their own," noted Vladimir Sychov, deputy director of the Institute of Medical and Biological Problems, the agency conducting the experiment.

The animals orbited for a month at an altitude of about 357 miles, which is much higher than the International Space Station's orbit of 250 miles. Most organisms, including humans, undergo physical changes in prolonged microgravity. Astronauts and cosmonauts undergoing multi-month missions on the International Space Station follow a rigorous exercise schedule intended to stave off microgravity-induced health problems.

Intended to study the biological effects of long-term weightlessness, the modified Bion-M life sciences satellite was equipped with internal cameras so that scientists could monitor the animals during flight. In addition, sensors tracked the heart rates and blood pressure of the mostly furry crew. Scientists monitored a variety of health metrics for the animals while the spacecraft beamed down information about the health of the animals and the conditions inside the capsule. The low survival rate among rodents "was to be expected," according to Sychov.

Ethics!

Although the US and the Soviet Union (later Russia) have launched long-duration manned space flights and amassed data on the subject since as far back as the early 1960s, detailed experimentation on humans exposed to prolonged microgravity is ethically sticky. The biological deficits incurred through long exposure to microgravity-including skeletal and muscular deterioration-might be irreversible.

One of the NASA experiments focused on how microgravity and radiation affect sperm motility in mice. If humans are going to visit other planets on long flights, Rayl said, it's important to understand if people will be able to procreate from sex in space. Some missions could take decades, so space-based reproduction might be a necessity.

Although one of the NASA scientists was examining the mice for sperm motility, reproduction while in the spacecraft had not been permitted. Only male mice had been selected for the journey, Rayl said.

"We often have very targeted scientific experiments where we have one investigator looking at, say, 'cardiovascular system function.' This [Bion-M1] is different because we have nine investigators [in] total looking at a whole organism approach to spaceflight," he said. "That's a very exciting development for us, that we're able to bring so many investigators to the table to really maximize the scientific return from this mission."

Bion-M1 is Russia's first mission dedicated to launching animals into space in 17 years. The last Bion mission carried rhesus monkeys, geckos, and amphibians into orbit for 15 days in 1996. The Bion-M1 mission is the longest flight of its kind in the Russian science program's 40-year history. It is important to note that the U.S. was the first country ever to launch a primate, sending a rhesus monkey named Albert to a sub-space altitude of 39 miles aboard a V2 rocket in June 1948.