If we are talking about using existing designs, then it makes even more sense to use either the Delta IV Heavy or the Atlas V Heavy of ULA (of course, the Atlas V is probably out of contention here as it uses Russian engines) than redesigning the existing four segment SRB's at a design cost of over $3 billion dollars. <br /><br />At its current capabilities the Delta IV Heavy (and as the Atlas V uses Russian Engines, I don't think congress would allow that) can place up to some 53,000 lbs into LEO (which is all that NASA needs from a first stage anyway). It would be relatively simple for ULA to redesign the Delta IV Heavy with two more attach points for a five Common Booster Core launch system, which would place as much as some 90,000 lbs into LEO, and totally eliminate NASA's weight problem with almost ANY capsule it desired! <br /><br />The EELV program was designed by the Air Force to be far cheaper than either the shuttle or the Titan IV to place very heavy military satellites into GEO. Just as an example, an SSME currently costs about $60 million each, and the shuttle requires three of them, on the other hand the RS68 of the Delta IV costs about $10 million each, and the Delta IV Heavy also requires three such engines. Of course the reuseablility of the SSME brings the over all costs down somewhat in itself, but not enough to overcome the cost difference of the RS68. <br /><br />This is because when the SSME was being designed and built by Rocketdyne, performance and weight were the prime considerations and cost was a secondary consideration, but when the RS68 was being designed and built, cost was the primary consideration and performance and weight (which is still very good for the RS68) were a secondary consideration.<br /><br />Also, the Common Booster Cores used for the Delta IV and the Atlas V are built in a far more assembly minded plant that the earlier rockets were. The only thing stopping these excellent (and already established) rockets from being as