What Rocket Am I?: Quiz 8

Clue 1: I launched Vanguard 1, the oldest satellite still in orbit.
Clue 2: My payload to LEO is about 9 kg.
Clue 3: My project was part of the International Geophysical Year.
Clue 4: I am a three-stage rocket designed for civilian space launches.
Clue 5: I was first successfully launched in 1958.
Clue 6: I stand 23 meters tall.
Clue 7: I was developed by the Naval Research Laboratory in the United States.

Yes, I am Vanguard.

Vanguard 1's solar cells were the first used in space, proving long-term power supply for satellites.