Vanguard satellite development. Vanguard was a Navy-led space program that had a series of high-profile launch failures and incidents. Eventually, in March 1958, Vanguard 1 became the second US satellite after Explorer 1 a month earlier, to be successfully launched into orbit. The Vanguard satellites, still orbiting 50 years after launch, were used as radio beacons for several years until their power failed. Their positions have subsequently been monitored to study atmospheric drag on satellites. Photographed in 1957.