A pioneer of Earth observation from space, the Vanguard 2 satellite launched Feb. 17, 1959. The satellite was the world’s first intended for meteorological observation, and followed on a series of test vehicles and failed satellite launches in the Vanguard program. The only previously successful Vanguard satellite, Vanguard 1, had launched a year earlier.
Vanguard 2 was intended to measure global cloud cover, and carried two photocells to scan Earth as it orbited the planet. Unfortunately, though the satellite achieved a successful orbit, residual propellant in the rocket caused a “wobble,” which made its data unusable. However, Vanguard 2’s successful sensor system and the valuable flight experience it provided laid the groundwork for future missions. It remains in orbit, and is expected to stay there for about 200 years.
