This undated artist's rendering released by NASA shows the Ares I crew launch vehicle during launch and the Ares V cargo launch vehicle on the launch pad. Officially, the space agency is still on track with a 4-year-old plan to spend $35 billion to build new rockets and return astronauts to the moon in several years. However, a top NASA manager is floating a cut-rate alternative that costs around $6.6 billion. (AP Photo/NASA)