Wednesday, March 11, 2015

50 Years Ago: Ranger Probes Explore the Moon

Ranger 8 launch from Cape Canaveral.

Fifty years ago on February 17, 1965, NASA launched the latest in its series of Ranger-class lunar probes. Ranger 8 blasted off from Cape Canaveral's LC-12 pad on an Atlas-Agena rocket, reaching Earth orbit at 185 kilometers altitude. The Agena second stage ignited and sent the Ranger 8 space probe on its way to the Moon on a course to reach the Lunar surface on February 20. The ranger series was designed to take as many pictures of the lunar surface as it could manage, and transmit them to the Earth before crashing into the surface.

Diagram of the Ranger block III spacecraft.

The Ranger probe was powered by twin solar panels throughout its journey. It made a mid-course correction using hydrazine thrusters. SIx cameras were carried on board, each with their own control system and transmitter for rapid transfer to Earth. Before it crashed, the cameras sent back 7,137 pictures before impact on the surface. The pictures were used by NASA to help plan future lunar landings for the Apollo program, including the first close-up pictures of the Apollo 11 landing site.

Picture of lunar surface from Ranger 8.

One more Ranger was planned in the program, for a launch a few weeks later in March.

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