The tragic loss of Space Shuttle Columbia threw the future of Hubble Space Telescope (HST) in doubt. The Columbia Accident Investigation Board report led NASA to the realization that astronauts must have someplace to go on orbit if the Shuttle is damaged, a requirement that cannot be met for a manned HST mission. Yet missions to HST are required, since HST was designed to be serviced periodically.
To address this problem, NASA is developing a robotic servicing mission to Hubble. On-orbit rendezvous and docking under tele-robotic or fully autonomous control involves a number of challenges that have not been fully resolved. One key challenge is how to bring two craft together in precise alignment to each other without an experienced astronaut on board. For this to be possible, sensors are needed to report relative distance, bearing, and orientation.
At Advanced Optical Systems (AOS), we have applied our ULTOR digital correlation system to the Hubble repair mission. The ULTOR system operates at approximately 10 Hertz and can accurately determine the relative distance, bearing, and orientation needed for semi- or fully-autonomous docking to HST. The system can operate using the HST berthing target or other features, including the HST itself. It is small and light enough to be placed on the servicing craft, thus avoiding orbit-to-ground communication latency issues. We will discuss the results of our testing with computer-generated imagery of the HST and with any hardware-in-the-loop simulations.