Orbiter Boom Sensor System

The Orbiter Boom Sensor System (OBSS) was a 50-foot (15.24 m) boom carried on board NASA's Space Shuttles. The boom was grappled by the Canadarm and served as an extension of the arm, doubling its length to a combined total of 100 feet (30 m).^[1] At the far end of the boom was an instrumentation package of cameras and lasers used to scan the leading edges of the wings, the nose cap, and the crew compartment after each lift-off and before each landing. If flight engineers suspected potential damage to other areas, as evidenced in imagery captured during lift-off or the rendezvous pitch maneuver, then additional regions could be scanned.

The OBSS was introduced to the shuttle fleet with STS-114, the "Return to Flight" mission executed by Discovery, and was flown on every mission after that until the retirement of the Space Shuttle fleet in 2011. It was used to inspect the shuttle for damage to the heat shield, officially called the Thermal Protection System (TPS), that could jeopardize the shuttle during re-entry. The decision to perform focused inspections of the TPS was prompted by the Space Shuttle Columbia disaster, in which Columbia was destroyed due to damage inflicted to its TPS during launch. The OBSS was central to focused inspections of the TPS, not only because it carried all the instruments necessary for detailed measurements and observations, but also because without it, the Canadarm was too short to reach to all the areas that needed to be surveyed.