— Ch. 1 · Origins And Objectives —
Ranger program.
~4 min read · Ch. 1 of 6
The Ranger program began in 1959 as a series of uncrewed space missions by the United States. Its goal was to obtain the first close-up images of the lunar surface through direct impact. Engineers designed spacecraft that would transmit images to Earth until they were destroyed upon hitting the Moon. Congress launched an investigation into management problems at NASA Headquarters and the Jet Propulsion Laboratory after early failures. The total research, development, launch, and support costs for Rangers one through nine reached approximately $170 million. JPL mission designers planned multiple launches in each block to maximize engineering experience and scientific value. They aimed to assure at least one successful flight despite the risks involved.
Early Block Failures
Ranger one launched on the 23rd of August 1961 but suffered a launch failure. It remained in a short-lived low-Earth orbit where it could not stabilize itself or collect solar power. Ranger two followed on the 18th of November 1961 with similar results. These early attempts left the spacecraft unable to survive long enough to reach the Moon. Problems with the Atlas-Agena launch vehicle kept both probes from their intended path. In 1962, engineers utilized the design for the failed Mariner one probe to Venus. A type of diode used in previous missions produced problematic gold-plate flaking in space conditions. This issue may have been responsible for some of the early failures. No significant science information was gleaned from these initial missions.Technical Architecture
Each Block three Ranger spacecraft carried six cameras on board. The camera system divided into two channels called P and F. Each channel had separate power supplies, timers, and transmitters. The F-channel included a wide-angle A-camera and a narrow angle B-camera. The P-channel held four cameras: P1 and P2 were narrow angle while P3 and P4 were wide angle. Leonard R Malling led the design and construction of these specialized systems. Camera preamplifiers used nuvistor valves to transmit high-resolution data before impact. The final F-channel image occurred between 2.5 and 5 seconds before impact at an altitude of about 10 kilometers. The last P-channel image arrived just 0.2 to 0.4 seconds before impact. These images provided better resolution than Earth-based views by a factor of 1000.