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?

Looking to the paragraphs following the above quote adds context:

This move was not driven by technical concerns, instead, the approach selected allows us to make a significant 'downpayment' towards Ares V with Ares I - lowering the overall integrated program risk to a 1st lunar landing:

- Where we had 2 upperstage engine developments (altitude start SSME and J-2X), we now have one (J-2X).

- Where we had 2 Shuttle RSRM-derived 1st stages (4 and 5 segment), we now have one (5 segment).

- With the 5 segment, we will use the same propellant (PBAN), same cases and joints/seals, same igniter, same nozzle hardware in a majority of components, a Shuttle developed, environmentally-friendly insulator, same aft-skirt and same TVC system as has been proven on 230 RSRM flights on Shuttle. In addition, 5 segment changes are anchored in a proof-of-concept 5 segment firing in October, 2003.

- Where we had a 2 step approach to a low cost core stage engine which would only be used by NASA (expendable SSME), we now have one with the RS-68, which fly's today on the Delta IV.
In making these changes, we were able to reduce our planned expenditures in getting to the moon while maintaining system performance and safety/reliability projections. Such trades are a normal part of a rigorous systems engineering approach which NASA is employing in its exploration efforts - it's interesting to note that the Saturn program went through 8 configuration changes from 1959 - 1962 resulting in the Saturn V, which took us to the moon.

True, the final product is more of a blend of EELV and shuttle derived and clean sheet than pure shuttle derived -- RSRMs & RS-68s & J-2X -- but so what?

I think "shuttle derived" is coming to mean "subsidizes existing shuttle infrastructure, contractor base, and workforce".

It uses the SRB, which means that the $400M/year continues to flow to Thiokol. Pratt gets paid to build RS-68s rather than SSMEs. It launches from LC 39 and is put together in the VAB. It's being designed by MSFC. So it is shuttle-derived in some important ways, which may be politically useful. Or they may not, who knows.