NASA and its Orion crew exploration vehicle (CEV) prime contractor Lockheed Martin are restructuring the design, development, test and evaluation contract, awarded in August 2006, following new CEV requirements that emerged from project reviews last November and December.

Lockheed expects the restructured seven-year deal to be agreed by May this year with increased costs in the short term but overall no change to the total contract award of $3.9 billion.

Requirements for the Orion that have already been dropped are two-failure tolerant specifications for some of its subsystems while others, such as the ability of the capsule to cope with Atlantic or Pacific sea-states for up to 36h before the crew can be recovered, are in negotiation.

Before the restructuring is agreed Lockheed expects Orion subsystem preliminary design reviews to start in the second quarter of this year and to continue through a final PDR for the entire CEV in the third quarter. The outcome of the requirements renegotiation and PDR reviews may also see a reduced level of reusability for Orion.

Lockheed Martin Space System's human spaceflight vice-president and general manager John Karas told Flight at NASA's third space exploration conference, in Denver, Colorado, on 26 February: "If you can reuse 50% of the vehicles 50% of the time, you can meet the life cycle costs."

Only the CEV's crew module is reusable, its service module is expendable. But landing in water could mean the crew module is not fully reusable unless the capsule is recovered with the crew still in it.

Orion is being designed to go to the Moon and Karas explained that while the service module's reduced propellant needs for an International Space Station mission would allow the capsule to use the very heavy heat shield needed for the skip re-entry necessary for a land landing, CEV lunar flight mass limitations preclude the heavy shield.

In an off-nominal land landing a Moon-capable Orion could save its crew but, Karas added, it would need a mix of a crushable zone and crew seat shock absorbers and the capsule would not be reusable. NASA has a study under way on the water- or land-landing baseline and a decision could be taken in March or April.

April may also see the PDR for the crew module's heat shield, developed by NASA Ames Research Center and Boeing. If successful this phenolic impregnated carbon ablator will then be handed over to Lockheed for integration into CEV.