Mr Jim wrote:
Does Project Score count? That was a specially-prepared Atlas B launched in
December of 1958 which put the booster (less the so-called stage zero
booster engines, of course) in orbit, with a radio transmitter/tape player
package that broadcast a recorded "message of peace" from President
Eisenhower. "Atlas - the ultimate weapon" has a chapter on it, with excerpts
from a BIPS article ("the talking satellite") about the mission.

The fact that it dropped the two outer engines probably disqualifies it
from the SSTO category.
With the later Atlas versions it might have been possible to get the
whole works in orbit, but with no real payload, so there was no reason
to do it.
I still remember Eisenhower's stirring Christmas message from orbit:
"This is the President of the United States speaking. Through the
marvels of scientific advance, my voice is coming to you from a
satellite traveling in outer space.
My message is a simple one: Through this unique means I convey to you
and all mankind, America's wish for peace on Earth and goodwill toward
men everywhere."
Only recently has the alternative version of the message come to light
in the voluminous archives of the Eisenhower presidential library:
"This is the Vice President of the United States speaking. Through the
marvels of scientific advance, my voice is coming to you from a
satellite traveling in outer space, launched by a rocket that could put
a hydrogen bomb in Red Square inside of one hour from the word "go".
My message is a simple one: Through this unique means I convey to you
and all mankind, America's wish for peace on Earth and goodwill toward
men everywhere.
Or else.
And that goes for you big eastern college-boy beatnik liberals also. No
good will for you, you pinkos.
The only peace you deserve is eternal peace. If Checkers ever laid eyes
on you, he'd bite you right on your big red ass." ;-)

Pat