NASA's Constellation rockets Ares I crew launch vehicle and the cargo carrying Ares V could be modified for future commercial use if proposals were made to the agency.

The US space agency's administrator Michael Griffin raised the prospect of Ares boosters being used for commercial purposes when answering an audience member’s question at the 2008 Experimental Aircraft Association's AirVenture air show held in Oshkosh, Wisconsin.

The question referred to the late US president Ronald Reagan’s policy that the Space Shuttle’s external tank (ET) could be used for commercial purposes once it separated from the orbiter and asked if that would be applied to the new Ares rockets.

Griffin replied: "The question was can modifications be put in early [for the Ares rockets] to enable re-qualification [for commercial purposes]. In principle yes but only if some one comes forward with a plan."

Watch Griffin answer the question in full in this video clip.

The development plan for the Ares boosters calls for the first test-flight of an Ares I representative rocket, Ares I-X, next year. Neither of Ares I’s stages reach orbit though, its upper stage separates from its Orion crew exploration vehicle (CEV) payload while the CEV is still on a suborbital trajectory. Orion’s own rocket motor then propels it into low Earth orbit.

The first Ares V cargo launch vehicle test flight V-Y will not take place till 2018 but its upper stage can reach orbit. It will initially be used as an Earth departure stage for manned Moon missions. Speaking at AirVenture on 29 July, NASA's 50th birthday, Griffin answered questions for over an hour about NASA's work on exploration, science and aeronautics.