Despite receiving more than $1 billion of development, NASA's Ares I crew launch vehicle (CLV) may not take part in Moon missions if the space agency concludes it can "human rate" its Ares V cargo launch vehicle (CaLV).

With a 2015 in-service date, the CLV would only take crew to the International Space Station for the station's final five years of operation, but then not operate in tandem with CaLV for Moon missions from 2020, as conceived. With the CLV as the half in NASA's "1.5 launch architecture" concept, NASA has claimed the duo would be safer than the Apollo programme's single-rocket method. In another possible change, NASA is interested in enhanced Ares V solid rocket boosters, when the CLV boosters were baselined for CaLV.

Ares V integration manager Stephen Creech says that guidance from NASA's Lunar Capability Concept Review is to study alternative booster options "in the event that [we] wanted more performance", until the level two lunar systems requirement review is published in June 2010. The Ares V development phase one contracts are expected by May 2009. The core and Earth departure stages' human rating study is part of phase one.

Another phase one aspect is a study of electromechanical actuators for the stages' thrust vector control. Work has already begun to evaluate electromechanical actuators as an alternative to the CLV solid rocket boosters' hydraulic actuators.

Source: Flight International