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Mapping the Moon: A Brief History of Lunar Cartography from Galileo to the Lunar Reconnaissance Orbiter

Project Ranger

NASA’s Ranger program, operated by the Jet Propulsion Laboratory at the California Institute of Technology, was a series of unmanned missions to the Moon during the mid-1960s. The objective of the program was to obtain high-resolution photographs of the lunar surface in advance of Surveyor and Apollo lunar landing missions.

Built to Crash

Ranger spacecraft were sent on a collision course to the Moon. They were designed to transmit close-up photographs of the lunar surface a few minutes before they crashed. The first six Ranger flights failed to reach the Moon. The final three flights successfully impacted the lunar surface, transmitting thousands of detailed images back to Earth.

Image of Ranger flight profile on approach to the Moon.

Ranger flight profile on approach to the Moon. Rangers were launched aboard Atlas-Agena rockets from Cape Canaveral, Florida. The probe was about 12 feet in height with two, five-foot solar panels that provided electrical power to the spacecraft. Image source: Gatland, Kenneth W. Robot Explorers. London, Blandford Press, 1972. View Source

Cameras

Each Ranger spacecraft contained six vidicon television cameras manufactured by RCA. The cameras had varying exposure times and fields of view. Three of the six cameras used 25-mm lenses; the other three had 76-mm lenses.

Image of a camera arrangement inside of a Ranger spacecraft.

Camera arrangement inside a Ranger spacecraft. Image source: Hall, R. Cargill. Project Ranger: A Chronology. Jet Propulsion Laboratory, 1971. View Source

Success with Ranger VII

After six failures, Ranger VII, launched July 28, 1964, and impacted the moon three days later in Mare Cognitum (the Sea That Has Become Known). The spacecraft transmitted over 4,300 images during the final 17 minutes of its flight. These were the first close-up images of the lunar surface. They revealed a landscape dotted with impact craters, even in areas that looked relatively smooth from Earth-based observations.

The first image of the Moon taken by a U.S. spacecraft.

The first image of the Moon taken by a U.S. spacecraft. Ranger VII took this photograph about 17 minutes before impact at a range of approximately 1,500 miles. The trio of large craters on the right are, top to bottom: Ptolemaeus, Alphonsus, and Arzachel. To the left of the craters is Mare Nubium (the Sea of Clouds). Image source: Jet Propulsion Laboratory. Ranger VII Photographs of the Moon Part II: Camera “B” Series. NASA, 1965. View Source

Rangers VIII & IX

In February 1965, Ranger VIII crashed in Mare Tranquillitatis (the Sea of Tranquility) approximately 43 miles from where Apollo 11 would land in July 1969. The probe sent back over 7,000 photographs. Ranger IX, the final mission, impacted the Moon near Alphonsus Crater in March 1965. The spacecraft transmitted over 5,800 images.

Ranger VIII photograph of Mare Tranquillitatis 5 seconds before impact. The image area is one mile across.

Ranger VIII photograph of Mare Tranquillitatis that was taken about five seconds before impact. The image area is approximately one mile across. Image source: Jet Propulsion Laboratory. Ranger VIII Photographs of the Moon. NASA, 1966. View Source