The Space Systems Laboratory (SSL) is part of the Aerospace Engineering Department and A. James Clark School of Engineering at the University of Maryland in College Park, Maryland. The Space Systems Laboratory is centered on the Neutral Buoyancy Research Facility, a 50-foot-diameter (15 m), 25-foot-deep (7.6 m) water tank that is used to simulate the microgravity environment of space. The only such facility housed at a university, Maryland's neutral buoyancy tank is used for undergraduate and graduate research at the Space Systems Lab. Research in Space Systems emphasizes space robotics, human factors, applications of artificial intelligence and the underlying fundamentals of space simulation. There are currently five robots being tested, including Ranger, a four-armed satellite repair robot, and SCAMP, a six-degree of freedom free-flying underwater camera platform. Ranger was funded by NASA starting in 1992, and was to be a technological demonstration of orbital satellite servicing. NASA was never able to manifest it for launch and the program was defunded circa 2006. For example, Ranger development work at the SSL continues, albeit at a slower pace; Ranger was used to demonstrate robotic servicing techniques for NASA's proposed robotic Hubble Servicing Mission.