Achieving orbit will be unlikely, but it must not be made impossible by design. This is not an 'orbit or bust' program, but going to orbit with or without payload should be the goal. It must be designed to allow retrofit of the RL-35 engines now under development. We conclude that a properly designed ship retrofitted with the RL-35 engines should achieve orbit. The design should take into account that this ship can fly incremental missions and modifications can be made after well designed flight test programs.
Early flights can incorporate safety equipment and structural reinforcements.
Experience will indicate possible modifications to increase capability. Payload considerations should play no part in the ship design. This is a flight test X vehicle, not a prototype for a new operational ship. These should be designed for incorporation into SSX-1. Note that this engine development program would be a supplement to SSX-1 and conducted in parallel.