NASA’s Orbital Space Plane (OSP) program is one step
closer to becoming the nation’s next space vehicle with the
successful completion of its Systems Requirements Review.
The review evaluated the vehicle’s concept design for
providing crew rescue and transfer for the International
Space Station.

The NASA-led review evaluated contractor designs based on
the primary design criteria, or Level 1 requirements, set by
the agency in February. The contractor teams designing the
OSP, The Boeing Company, Seal Beach, Calif.; Lockheed
Martin, Denver; and a team including Orbital Sciences Corp.,
Dulles, Va., and Northrop Grumman, El Segundo, Calif., have
been working to develop system specifications, including
systems analysis, trade studies, and concept feasibility in
preparation for the review.

The System Requirements Review includes analysis of
requirements and supporting technical documentation to
ensure the system is safe, reliable, maintainable and
affordable. It is one in a series of reviews that occurs
before the Orbital Space Plane system is built.

In addition, the review set Level 2 requirements, guidelines
that further narrow the scope and add a level of detail to
the system design. The Level 2 requirements address
guidelines for safety, launch, emergency-return and crew-
transfer missions, mission frequency, on-orbit mission
duration, contingency cargo requirements, and docking and
interfacing with the Space Station. The requirements also
include limits on the gravitational loads on the crew,
health monitoring of the crew, communications with the Space
Station and mission control on Earth, reliability, system
lifetime, and logistics. Each level of requirements provides
a narrower parameter for the design of the vehicle system.

“This review is a critical step in making the Orbital Space
Plane a reality,” said Dennis Smith, Orbital Space Plane
program manager. “These requirements are the instruction
manual for designing the entire system that will provide
safe, reliable access to and from the International Space
Station,” he said.

The Level 2 requirements are contained in a package of
technical documents and plans, which include the Orbital
Space Plane Systems Requirements Document, the International
Space Station Interface Requirements Document, the Orbital
Space Plane to Expendable Launch Vehicle Interface
Definition Document, and the Orbital Space Plane Human
Rating Plan, along with other reference and guidance
documentation. An executive summary of the Level 2
requirements is on the OSP Web site. Following review of the
documentation for export-control and security issues, the
Level 2 documentation also will be available online.

A System Definition Review is scheduled for November 2003.
It will include a further, more focused evaluation of the
concept design including risk reduction and breakdown of the
functional elements of the system based on the Level 2
requirements. The review also will set Level 3 requirements
for the Orbital Space Plane system based on evaluation of
the program objectives and contractor feedback.

The program is scheduled to issue a request for proposal to
the three contractor teams in November 2003. A decision to
develop a full-scale vehicle system is expected in 2004.

For the executive summary and other information about the
Orbital Space Plane, visit:

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