[CasearianDaoist]

No there have been Delta Four launches = NSA birds I think. I do not think that we need a bigger booster. Just need to man rate the Delta $

[Frank_Discussion]

So right you are. There still isn't a Delta 6, though.

Man-Rating is expensive, but that's what I expect for the CEV in the short run, some sort of Saturn variant in the medium run, Fully reusable in the long run.

[So Cal Rocket]

Delta IV Heavy:

First flight is this year. Can lift 50,000lbs to LEO - a real heavy lift capability. Manrating would be expensive, but cheaper than a new design.

Don't invest the money in developing new big dumb boosters... spend it on nuclear engines for the crew exploration vehicle.