The Constellation Program to develop a next-generation spacecraft for missions to the moon and Mars completed its half-year-long system requirements review, NASA announced.

Constellation will include the Orion crew exploration vehicle, a space capsule carrying space voyagers, and the Ares rocket system that will loft Orion into space. NASA last year chose Lockheed Martin Corp. [LMT] to develop Orion, and NASA later this year will choose the contractor to build Ares.

The Constellation system in the middle of the next decade will replace the aging space shuttle fleet that will retire in 2010, leaving the United States with a five-year gap