Slice of History: Ranger Impact Limiter
Each month in “Slice of History” we feature a historical photo from the JPL Archives. See more historical photos and explore the JPL Archives at https://beacon.jpl.nasa.gov/.
This photo was taken in November 1960 to show the lightweight balsa wood impact limiter that was to be used in the NASA Jet Propulsion Laboratory’s Ranger Block II spacecraft design (Rangers 3, 4, and 5). The woman holding the sphere is Systems Design secretary Pat McKibben. The sphere was 65 cm in diameter, and it surrounded a transmitter and a seismometer instrument that was designed by the Caltech Seismological Laboratory. The sphere would separate from the spacecraft shortly before impact and survive the rough landing on the moon. The capsule was also vacuum-filled with a protective fluid to reduce movement during impact. After landing, the instrument was to float to an upright position, then the fluid would be drained out so it could settle and switch on.
Due to a series of malfunctions in 1962, these three Ranger spacecraft either crashed without returning data or missed the moon. In July 1964, the first successful Ranger spacecraft, Ranger 7, reached the moon and transmitted more than 4,000 images to Earth.