ASTROGEOLOGY

Richard J. Pike

Photo of Branch of Astrogeology

Eugene Shoemaker, the pioneering astrogeologist who first worked out the formational mechanics of Meteor Crater during investigations on Arizona's Colorado Plateau in the late 1950s, believed that astronauts in the fledgling program to put man on the Moon would benefit from training in geology. In 1957, Gene prepared a preliminary map of the Moon's Copernicus Crater. From photographs and telescopic measurements, he unraveled the sequence in which layers of lunar materials were deposited. This pathbreaking map and Gene's infectious enthusiasm convinced NASA officials to sponsor a lunar geology program to be directed by the USGS. On the Stanford campus in 1960, Shoemaker ran into Henry Moore, whom he had first met when both were working for the USGS in Colorado. He convinced Moore to rejoin the USGS and become part of the Branch of Astrogeologic Studies that the ebullient Shoemaker had persuaded the USGS to create. Others soon followed.

Within a year, Shoemaker's dream was officially a going concern in the since-demolished Building 4 on the Menlo Park campus, with Gene serving as its first Chief Scientist. During the early 1960s, Shoemaker introduced crater counting as a method to date the lunar surface, led USGS teams that investigated the Moon's structure and history, and developed methods of remote geologic mapping from telescopic images of the Moon. Several boots-and-hammer geologists from other branches joined the effort. At the Lick Observatory on Mt. Hamilton, Shoemaker, Moore, Mike Carr, Don Wilhelms, Hal Masursky, Dan Milton, Newell Trask, Dick Eggleton, and others made the visual Observations needed to compile 1:1,000,000-scale photogeologic quadrangles of the lunar frontside.

Early in 1963 Shoemaker decided to move the branch headquarters to Flagstaff, Arizona. Some of the original branch members opted to remain in Menlo Park; others moved to Flagstaff. Future growth would be mostly in Flagstaff.

Branch geologists from both Menlo Park and Flagstaff participated actively in the successful spacecraft missions leading up to Apollo: Ranger, Surveyor, and Lunar Orbiter. USGS astrogeologists served as advisors to NASA, aiding in the choice of Apollo landing sites and helping train the Apollo astronauts in field geology in preparation for the lunar landings of the late 1960s. When the astronauts returned samples from the Moon's surface, Henry Moore and Howard Wilshire were among the scientists who described and analyzed those rocks. They and other Menlo Park astrogeologists, including Keith Howard, Carroll Ann Hodges, and Dick Pike, studied landforms on photographs of the Moon's surface taken from lunar orbit on the later Apollo missions.

With the early demise of Project Apollo in 1972, the ranks of the Menlo Park group thinned as its orientation gradually shifted from lunar objectives. Through the 1970s, the remaining Branch members conducted photogeologic studies of Mars from results of the 1971 Mariner 9 Mission and of Mercury from the 1973 Mariner 10 Mission. Spurred by early indications that the planet Mars had once hosted abundant water, Carr and Moore became increasingly involved with mission planning, site selection, and science operations for exploring Mars, culminating in the successful 1976 Viking landers and orbiters, the 1997 Pathfinder/Sojourner rover mission, and the still spectacularly productive 1999 Mars Global Surveyor. Between Martian missions, Carr and the handful of remaining Menlo Park people participated in the 1977 Voyager Mission to the outer planets and satellites and the 1989 Galileo Mission to Jupiter and its moons. Menlo Park's participation in the exploration of Mars continues today in Carr's major role in the Mars Exploration twin-Rover Mission that recently drilled into Martian sedimentary bedrock rock and at last identified unequivocal evidence for the presence of water on the Red Planet.

Upon Mike Carr's retirement in June 2004, the four-decade-plus history of planetary investigations in Menlo Park draws to a close.

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