Space Integrated GPS/INS

Space Integrated GPS/INS (SIGI) is a strapdown Inertial Navigation Unit (INU) developed and built by Honeywell International to control and stabilize spacecraft during flight.

SIGI has integrated global positioning and inertial navigation technology to provide three navigation solutions : Pure inertial, GPS-only and blended GPS/INS.

Current and Future Usage
SIGI have been employed on the International Space Station, the Japanese H-II Transfer Vehicle (HTV) the Boeing X-37, CST-100 Starliner and X-40.

SIGI is also proposed as the primary navigation system for Orion, which is scheduled to replace the Space Shuttle.