Orbiter Boom Sensor System

The Orbiter Boom Sensor System (OBSS) is a 50-foot boom carried on board NASA's Space Shuttles. The boom can be grappled by the Canadarm and serves as an extension of the arm, doubling its length to a combined total of 100 feet (30 m). At the far end of the boom is 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 suspect potential damage to other areas, as evidenced in imagery captured during lift-off or the rendezvous pitch maneuver, then additional regions may 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 since. It is used to inspect the shuttle for damage to the heatshield, officially called 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 a shuttle was destroyed due to damage inflicted to the heatshield during lift-off. The OBSS is central to focused inspections of the TPS, not only because it carries all the instruments necessary for detailed measurements and observations, but also because without it the Canadarm is too short to reach to all the areas that need to be surveyed.