Space agency not yet sure of Pentagon's role as it ponders new-generation alternatives

Industry is hoping for guidance from NASA by mid-November on the future direction of the Space Launch Initiative (SLI), amid signs the US space agency could proceed first with an orbital spaceplane (OSP) and delay a next-generation reusable launch vehicle (RLV).

The OSP could be carried into orbit on an evolved expendable launch vehicle (EELV) as early as 2009 to meet NASA's need for an International Space Station (ISS) crew rescue and transfer vehicle. The mini-shuttle may also have to meet US Air Force requirements for a military spaceplane.

NASA has delayed the SLI system requirements review scheduled for November until the Department of Defense's role has been ascertained, the ISS requirements determined and the agency's future space transport needs firmed up. The three SLI prime contractors expect to receive 10-month extensions to the RLV architecture definition contracts, which are scheduled to end in May.

The space agency is looking at a range of options to meet its ISS requirements. These include: buying additional Soyuz flights from Russia; launching an Apollo-type crew capsule; resurrecting the cancelled X-38 "lifeboat"; and developing a two-way crew transfer and rescue vehicle for launch by EELV or RLV.

A study conducted by the SLI primes this year indicated a two-way vehicle would be only slightly more expensive to develop than a one-way lifeboat. Orbital Sciences, which is working on the OSP within Northrop Grumman's SLI team, estimates developing and building four vehicles would cost $5-6 billion. Developing a second-generation RLV would cost $20-30 billion.

Orbital's OSP is a 20,500kg (45,000lb) vehicle that could be launched by a Boeing Delta IV or Lockheed Martin Atlas V EELV to carry up to five crew to the ISS, where it would stay for 90-120 days before returning with up to seven crew. The vehicle would be able to fly autonomously both ways, but be capable of manual control.

EELV launches would require a crew escape system to meet safety requirements. Orbital has settled on a combined launch escape and orbital manoeuvring propulsion system with six liquid rocket motors, four of which could be ignited on the pad to boost the OSP to safety.

Orbital's OSP concept separates crew and cargo transport and requires additional launches of an unmanned reusable space platform and modular payload carriers for on-orbit servicing missions. SLI contractors Boeing and Lockheed Martin are looking at larger orbiters able to carry crew and cargo

Source: Flight International