In certain fields, small is always beautiful. One such field is that of artificial satellites. The smaller a satellite is, less fuel it spends to get up in orbit or to navigate. Also it is harder to detect, and can perform intricate moves much more easily that its larger cousins.
With this in mind, NASA's Johnson Space Center has built a volley-ball sized satellite, called Miniature Autonomous Extravehicular Robotic Camera (Mini AERCam). Weighing about 10 pounds, the craft will be used for remote viewing and inspection on future human spaceflight missions.

AERCam (Courtesy: ScienceDaily)The vehicle is designed with a central ring that houses the power and propulsion system. Batteries are lithium-ion with six hours of operational time. The propulsion system is designed for cold-gas xenon, which packs more densely than nitrogen, but is compatible with low-cost nitrogen in the current ground test configuration. Attitude and position control are achieved with the use of twelve thrusters, distributed across four thruster pods around the central ring. The batteries are rechargeable and a port is provided for refueling:).
Early development is funded by the Space Shuttle Program Office, which is considering using Mini AERCam to inspect the Shuttle's heat shield in space. The nanosatellite will not be used on the Return to Flight mission (STS-114), but holds long-term promise for future space operations.
The craft could be deployed and retrieved many times during a single space mission, with the use of a hangar-based docking system located on the exterior of the vehicle. Other features include custom avionics based on the PowerPC 740/750 microprocessor, "camera-on-a-chip" imagers with video compression, micro electromechanical system gyroscopes, precise relative GPS navigation, digital radio frequency communications, micro-patch antennas, digital instrumentation networking and compact mechanical packaging.
Hopefully, in-space inspection by such satellites will prevent tragedies such as the Columbia disaster.