GRAHAM WARWICK / WASHINGTON DC
Requirement issued for vehicle to provide ISS rescue capability no later than 2010
NASA has released the top-level requirements for the Orbital Space Plane (OSP), which is planned to be launched on an expendable vehicle to provide crew rescue and crew transfer capability for the International Space Station (ISS). The OSP fleet would assure access to the ISS and offload the three surviving Space Shuttle orbiters, which would be used for heavylift cargo missions.
The "Level I" OSP requirements are for a vehicle able to carry at least four ISS crew members and provide a rescue capability beginning no later than 2010, and a transport capability to and from the station by 2012 at the latest. Studies have been conducted into vehicles able to carry up to seven crew.
The OSP will be launched initially on a Boeing Delta IV or Lockheed Martin Atlas V evolved expendable launch vehicle (EELV), but could be carried eventually on any next-generation reusable launch vehicle that may emerge from NASA's recently restructured Space Launch Initiative (SLI).
The requirements include a risk of crew loss lower than the Russian Soyuz emergency egress vehicle on the rescue mission, and lower than the Shuttle on the transport mission. Compared with the Shuttle, NASA wants the vehicle to take less time to prepare and launch, and be more manoeuvrable in space.
An autonomous orbital technology demonstration is planned for 2006 using Boeing's X-37, and Lockheed Martin is under contract to build a launchpad abort demonstrator. An escape system will be needed to reduce the risk of crew loss, as the EELVs are not man-rated.
Although Boeing, Lockheed Martin and Orbital Sciences teamed with Northrop Grumman have focused on a mini-shuttle, NASA's requirements do not rule out other approaches, including a Soyuz-type capsule or a development of the cancelled X-38 lifting-body lifeboat.
Source: Flight International
