NASA’s Project Constellation program has been overhauled to include a slightly smaller Crew Exploration Vehicle (CEV) and a new human-rated booster with an Apollo-era upper stage engine.

Project Constellation is the name NASA has given for the effort to develop hardware necessary to replace the space shuttle and return astronauts to the Moon late next decade.

NASA still intends to make use of the solid-rocket booster technology that has helped lift the space shuttle off the pad for a quarter century. But the agency recently approved CEV launcher plans calling for development of a new five-segment solid-rocket booster instead of the four-segment motor currently in production.