What Rocket Am I?: Quiz 7

Clue 1: I launched the first American orbital communications satellite, SCORE.
Clue 2: I am the first American ICBM adapted for space launches.
Clue 3: I achieved first orbital launch in 1958.
Clue 4: I use a stage-and-a-half design.
Clue 5: I carried Mercury astronauts into orbit.
Clue 6: My modern versions can lift over 20,000 kg to LEO.
Clue 7: I was developed by Convair for the United States Air Force.

Yes, I am Atlas.

My balloon tank design, where the structure is pressurized to maintain shape, was a revolutionary innovation in rocketry.