Mapping the moon
“Make precision maps of the moon.” This was the daunting 1957 assignment given to Charles F. Campen, a Croasdaile Village resident today who then was director of the Lunar and Planetary Exploration Branch, Geophysics Research Directorate of the U. S. Air Force.
The Air Force and, eventually NASA, needed to know exactly where our spacecraft should land and how astronauts would orient themselves as they would move about in this new, very unfriendly environment.
A new impetus had been given to this work when, with little warning, the Soviets successfully launched Sputnik I, the first low-orbit Earth satellite, Oct. 4, 1957. This was followed by Luna 3 which took the first pictures of the back side of the moon on Oct. 7, 1959. The “space race” was on full-bore.
Despite the 229,000 miles that separate Earth from its only natural satellite, human interest has been drawn to the moon for thousands of years. The Babylonians are thought to have made the first known maps of the moon circa 700 B.C. These included mythological, philosophical and spiritual interpretations. But would they, in their wildest imaginations, have believed humans would some day walk on this orb that so often dominated the evening sky? It’s doubtful.
There followed many naked-eye moon sketches and theories about the moon’s physical properties. But it was Galileo’s invention of the telescope in 1609 that brought the moon visually closer. This enabled a profusion of moon photographs validating some long-held theories and disproving others.
Early in 1958, Campen, a physicist, had to identify and recruit top scientists representing a variety of disciplines from all over the world. The first of these was Gerard Kuiper, who was at that time director of the Yerkes and MacDonald Observatories and thought to be the leading authority on the moon. Another key scientist was British astronomer Zdenek Kopal of the University of Manchester; he had new ideas on how best to photograph the moon. He suggested using the Pic du Midi Observatory in the French Pyrenees. Its 8,900-foot altitude is above most dust and turbulence which could have been problems with American observatories. But the relatively narrow 24-inch aperture of the Pic du Midi telescope was a limiting factor.
A bit of intrigue was introduced when the Air Force agreed to “loan” a 40-inch telescope to the University of Manchester with the tacit understanding it would soon be passed along to Pic du Midi. This caused ruffled feathers which were admirably smoothed by Kopal, and it literally gave the program a new perspective.
With enhanced moon pictures from Pic du Midi Observatory, Kopal and Kuiper were able to considerably improve estimates of the height and shape of lunar landmarks. They showed the depth and sides of moon craters and moon mountains, originally thought to be deep and precipitous, are relatively shallow and gradual. They did this with a series of time lapse photos of shadows cast by these features. Apollo astronauts would later verify and improve these findings with point-to-point measurements.
A consensus was needed about several issues before work on moon maps started. One of these was the mirror-image effect. Looking at the moon is like looking in a mirror; left and right, and east and west appear to be reversed. This wouldn’t do for astronauts. They wanted east and west to be in their usual places and this became the standard for moon maps.
A bigger problem was deciding where on the moon to locate the prime meridian from which to measure longitude. At first, few scientists agreed where this should be, but they ultimately chose the small crater Mösting near the center of a full moon as seen from Earth.
To decide on many of these and more complicated problems, Campen set up a conference of scientists from all over the world. Entitled “Problems of Lunar Topography,” it was held in France in April 1960 hosted by Jean Rösch, director of the Pic du Midi observatory. During and following this conference, Campen worked closely with Kopal and Kuiper and they formed new scientific working groups. Together, they developed prototype moon maps, but arranged to have The Aeronautical Chart and Information Center in St. Louis make final copies.
This organization had been preparing air-navigation charts for the Department of Defense for many years. The scale of their maps varied according to a number of variables, but 1 to 1,000, 000 was chosen for Moon maps that guided astronauts throughout the Apollo program.