Space Shuttle missions designated STS-3xx (officially called Launch On Need (LON) missions) were rescue missions which would have been mounted to rescue the crew of a Space Shuttle if their vehicle was damaged and deemed unable to make a successful reentry. Such a mission would have been flown if Mission Control determined that the heat shielding tiles and reinforced carbon-carbon panels of a currently flying orbiter were damaged beyond the repair capabilities of the available on-orbit repair methods. These missions were also referred to as Launch on Demand (LOD) and Contingency Shuttle Crew Support. The program was initiated following loss of Space Shuttle Columbia in 2003 during that Shuttle's investigation board. No mission of this type was launched before the Space Shuttle program ended in 2011.
Procedure The orbiter and four of the crew which were scheduled to fly the next planned mission would be retasked to the rescue mission. The planning and training processes for a rescue flight would have allowed NASA to launch the mission within a period of 40 days of its being called up. During that time, the damaged (or disabled) shuttle's crew would have to take refuge on the International Space Station (ISS). The ISS was able to support both crews for around 80 days, with oxygen supply being the limiting factor. Within NASA, this plan for maintaining the shuttle crew at the ISS was known as Contingency Shuttle Crew Support (CSCS) operations. Up to STS-121 all rescue missions were to be designated STS-300. In the case of an abort to orbit, where the shuttle could have been unable to reach the ISS orbit and the thermal protection system inspections suggested that the shuttle could not have returned to Earth safely, the ISS may have been capable of descending to meet the shuttle. Such a procedure was known as a joint underspeed recovery.
* – originally scheduled to be Endeavour, changed to Discovery for contamination issues. To save weight, and to allow the combined crews of both shuttles to return to Earth safely, many shortcuts would have had to be made, and the risks of launching another orbiter without resolving the failure which caused the previous orbiter to become disabled would have to have been faced.
Flight hardware A number of pieces of Launch on Need flight hardware were built in preparation for a rescue mission including:
An extra three recumbent seats to be located in the aft middeck (ditch area) Two handholds located on the starboard wall of the ditch area Individual Cooling Units mounting provisions Seat 5 modification to properly secure in a recumbent position Mounting provisions for four additional Sky Genie egress devices (see picture) Escape Pole mounting provisions for three additional lanyards
Remote Control Orbiter
The Remote Control Orbiter (RCO), also known as the Autonomous Orbiter Rapid Prototype (AORP), was a term used by NASA to describe a shuttle that could perform entry and landing without a human crew on board via remote control. NASA developed the RCO in-flight maintenance (IFM) cable to extend existing auto-land capabilities of the shuttle to allow remaining tasks to be completed from the ground. The purpose of the RCO IFM cable was to provide an electrical signal connection between the Ground Command Interface Logic (GCIL) and the flight deck panel switches. The cable is approximately 28 feet (8.5 m) long, weighs over 5 lb (2.3 kg), and has 16 connectors. With this system, signals could be sent from the Mission Control Center to the unmanned shuttle to control the following systems:
Auxiliary Power Unit (APU) start and run Air Data Probe (ADP) deployment Main Landing Gear (MLG) arming and deployment Drag chute arming and deployment Fuel cell reactant valve closure Pitot tube clearing check The RCO IFM cable first flew aboard STS-121 and was transferred to the ISS for storage during the mission. The cable remained aboard the ISS until the end of the Shuttle program. Prior to STS-121 the plan was for the damaged shuttle to be abandoned and allowed to burn up on reentry. The prime landing site for an RCO orbiter would be Vandenberg Air Force Base in California. Edwards Air Force Base, a site already used to support shuttle landings, was the prime RCO landing site for the first missions carrying the equipment; however Vandenberg was later selected as the prime site as it is nearer the coast, and the shuttle can be ditched in the Pacific should a problem develop that would make landing dangerous. White Sands Missile Range in New Mexico is a likely alternate site. A major consideration in determining the landing site would be the desire to perform a high-risk re-entry far away from populated areas. The flight resource book, and flight rules in force during STS-121 suggest that the damaged shuttle would reenter on a trajectory such that if it should break up, it would do so with debris landing in the South Pacific Ocean. The Soviet Buran shuttle was also remotely controlled during its entire maiden flight without a crew aboard. Landing was carried out by an onboard, automatic system. As of March 2011 the Boeing X-37 extended duration robotic spaceplane has demonstrated autonomous orbital flight, reentry and landing. The X-37 was originally intended for launch from the Shuttle payload bay, but following the Columbia disaster, it was launched in a shrouded configuration on an Atlas V.
Sample timeline Had a LON mission been required, a timeline would have been developed similar to the following:
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