Mars Mice

Each mouse's wastes will be collected in a compartment beneath its habitat; the compartment will contain a urinalysis system checking for biomarkers that indicate bone loss.

Each habitat will also be equipped with a body mass sensor, which will take frequent readings. This will also allow the researchers to track how the weight of the mice changes over the course of the five weeks.

Each mouse will also have toys to keep it busy. "We may give them a wooden block to chew on," says Wooster. That'll keep them happy, and will also prevent them from chewing on the habitat. They might have a small tube to run through.

No wheels, though, says Wooster, because NASA has learned that exercise can counteract some of the effects of low-gravity on astronauts. A mouse with a wheel in its cage can actually run several miles a day. "We don't want to give the mice a countermeasure in terms of exercise."

The students will be using only female mice, says Wooster. That's partly because female mice eat slightly less than male mice, decreasing the mass that must leave Earth. But more importantly, some studies suggest that females are affected more strongly by lowered gravity than the males.

Those studies, though, weren't conducted in true partial gravity. Rather, they were done by suspending the hind legs of the animals, so that the mice are only able to feel part of their weight on the ground. The simulated Mars gravity inside the Biosatellite will be much more realistic.

Credit: MarsGravity.org Much of the Mars Gravity Biosatellite is still on the drawing board. Shown here is a cutaway design diagram of a mouse habitat for the spacecraft.

Through the three participating universities, more than 250 students have been involved in the Biosatellite project. The project is being led and coordinated by MIT, which is also managing the animal habitats and life support systems. The University of Washington is in charge of providing electrical power, propulsion, attitude control, thermal control, and all the communications to the ground. The University of Queensland is in charge of the entry, descent, and landing systems, including the heat shields and parachutes.

"I think that one of the big contributions of the Biosatellite," says Wooster, "is the educational benefit for the students involved." So many people, he says, have been inspired by this project, and have learned from it. "Plus we're going to be getting back information that nobody's ever had before, data that have been missing in the planning of human missions to Mars."

How might humans respond to gravity on Mars?

With the successful landing of NASA's rover Opportunity, that question seems closer and closer to one we'll need to solve.