Here’s an interview with Danny Davis, manager of the ARES I upper stage at Marshall. I wish that Ross had asked about roll control, though.

I find this fascinating, albeit confusing:

NASA selected a Shuttle-derived launch architecture after a thorough apples-to-apples study last Summer – the Exploration Systems Architecture Study. NASA carefully weighed a wide variety of launch options for both crew and cargo – a Shuttle derived architecture was the clear winner when considering total cost, schedule and safety/reliability to achieve an exploration-capable system. NASA did not do this in a vacuum – in fact, we received inputs from industry, including studies funded by the agency, in the year prior to ESAS. The ESAS results were independently reviewed and concurred-in by experts outside the agency.

Last Winter and Spring, after a series of trade studies, NASA elected to alter the launch architecture to a 5 segment RSRM-derived 1st stage and a J-2X upperstage for Ares I and an Ares V core stage powered by an RS-68 (still boosted with a 5 segment RSRM and a J-2X earth departure stage).

So, are they saying that they originally were Shuttle derived, but have backed off from that ( with the abandonment of the SSME, there’s nothing left of the Shuttle derivation other than RSRMs), or that they recognize that the initial choice was mistaken? Are they still claiming that it’s significantly Shuttle derived?