The 400-kilogram Mars Gravity Biosatellite will fly in a Low Earth Orbit (LEO) just 200 miles above the Earth's surface—roughly the altitude of the International Space Station — where it will sweep around the planet more than a dozen times each day. After 5 weeks, the re-entry capsule will separate from the primary spacecraft to return the mice safely to a landing zone in the Australian desert. If you are within ~30 degrees of the equator, you may be able to see it pass overhead many times during the course of the mission.

To generate "artificial gravity" for the animals on board, the satellite will spin rapidly, making roughly one rotation every two seconds (34 rpm). This inward acceleration will simulate the force of gravity on the Martian surface (roughly one-third that of Earth), as depicted in science fiction films like 2001: A Space Odyssey. Due to the rotating environment, the animals may initially experience mild dizzyness, like the feeling of stepping off a merry-go-round; however, humans have been shown to adapt quickly to the peculiar sensations of centrifugation.

To provide symmetry for both vehicle and payload, the cylindrical spacecraft will rotate about its central axis, providing artificial gravity outwards against a curved floor. This axis will be pointed towards the sun to provide maximum lighting to the solar panels deployed outward from the main body; these will provide power to the onboard flight computer, communications equipment, data monitoring devices, and life support systems. A solid rocket motor will provide de-orbiting capability, while small attitude control thrusters regulate spacecraft orientation and rotation rate. At the conclusion of the mission, the carrier spacecraft will jettison the small re-entry capsule, containing the payload and vital systems, which will penetrate the upper atmosphere and navigate a precise touchdown in the designated recovery area.

The Systems Engineering team, based at MIT, is responsible for determining the overall system architecture, keeping track of interfaces and interactions between the three main subsystems, and assessing options for launch vehicles and ground communication stations. Using advanced software and modeling techniques, team members are able to assess trade-offs between configuration options, which are then passed to subsystems for more detailed work. By allocating resources and constraints across the entire development process, they ensure that the spacecraft and its supporting infrastructure will come in under budget and within the tight mass and volume restrictions imposed by launch.