Rand Simberg wrote:
The old Atlas could have come pretty close. With a small enough
payload, it might have been able to.


That would be fun to figure out; the weight of the aft skirt and its
engines versus that of the LEO payload.
The Atlas H 1/2 stage weighed 8,038 lb according to Encyclopedia
Astronautica; payload to LEO is 8,000 pounds, so with a lightweight
aerodynamic nosecone, who knows?
You'd be able to strip some weight off of the 1/2 stage because it
wouldn't have to separate, so the plumbing could be simpler.
It'd be a mighty low orbit, but you might be able to do it.

Pat