changed by the addition of the ACC. If the STS is launched carrying less than the maximum mass, this leaves excess mass to orbit capability which may be exploited by mission planners using an ACC. This could be payload such as communications satellites that will generate additional revenue for that particular sortie. This would allow non-revenue generating sorties such as planetary missions, science missions, DOD missions. Spacelab missions, or Space Station vists to generate revenue that they would not be able to do otherwise. It also gives the mission planner and scheduler an option that can be used to recover from the impact of a mission cancellation. If a flight is cancelled, rather than impact the entire flow for years to come by bumping payloads from flight to flight, the planner could fly a few loaded ACCs on appropriate future missions to catch up. The ACC can be configured to carry almost everything that can be currently carried in the cargo bay within the limits of a length of 20 feet (26). If a payload is designated for an ACC mission which makes the ACC the primary cargo carrier, the volume remaining in the cargo bay can carry additional payload. The figure that follows shows a cross section of possible ACC payloads including Space Station modules, storm shelters, satellite modules, Centaur G booster, wide OTVs, cryogenics scavenging, large diameter mirrors and antennas, service modules, lifeboats, entry ports for ET based structures, and shuttle mission enhancements. A proposed ACC payload includes the servicing structure for the Space Telescope. A typical mission scenario would be to launch the Orbiter, deploy satellites from the payload bay, retrieve the service structure from the ACC with the RMS while the rendezvous with the Space Telescope is conducted, and conduct the necessary servicing of the telescope (45, 48). The ACC can also carry thrusters in the skirt which can be used to either boost the tank into a higher orbit or deorbit it to a cotrolled splashdown in the ocean. The ACC is designed for minimal impact in current STS operations. It can be constructed using available tooling within the Michoud facility. It has minimal impact on the tank itself and the interfaces between the ACC and ET are relatively simple. The largest impact on the orbiter will be adapting the flight software to an ACC mission. Total cost of the ACC is around $150 - 250 million (4, 48) and it can be flown within three years of the decision to buy. Like the rest of the ET based applications studied, this is a relatively simple, low cost enhancement which has a very high return and significant positive impact on the STS.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==