Ranger Block I Design (Rangers 1 and 2)

Artist's concept for the first generation Ranger spacecraft.

Ranger was originally designed, beginning in 1959, in three distinct phases, called “blocks.” Each block had different mission objectives and progressively more advanced system design.

Block 1, consisting of two spacecraft launched into Earth orbit in 1961, was intended to test the Atlas/Agena launch vehicle and spacecraft equipment without attempting to reach the Moon.

Problems with the early version of the launch vehicle left Ranger 1 and Ranger 2 in short-lived, low-Earth orbits in which the spacecraft could not stabilize themselves, collect solar power or survive for long.