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Sharp, Robert Phillip

Sharp, Robert Phillip

(b. 24 June 1911 in Oxnard, California; d. 25 May 2004 in Santa Barbara, California), geologist, geochemist, and geomorphologist known for his interest in the exploration of planetary surfaces as well as for his work in other fields of geology.

Sharp was the oldest son of two fruit growers, Julian Hebner Sharp and Alice (Darling) Sharp. He graduated from Oxnard Union High School and the California Institute of Technology (Caltech), where he earned a BS in 1934 and an MS in 1935, both in geology. He then completed his PhD at Harvard University in 1938. While an undergraduate at Caltech, Sharp excelled in athletics as the quarterback of the university’s football team. He married Jean Prescott Todd in 1938. The couple had two children, both adopted.

Sharp became an assistant professor in the geology department of the University of Illinois at Urbana after he finished his PhD. He taught at Illinois from 1938 until 1943, when he was called to wartime service in the U. S. Army Air Forces (USAAF). He rose to the rank of captain while he was assigned to USAAF’s Arctic, Desert, and Tropic Information Center, where he worked until 1945. After the end of the war Sharp returned to academia as a full professor in the University of Minnesota’s geology department from 1945 to 1947. He left Minnesota for Caltech in 1947. Sharp completed his career at his alma mater as a professor of geomorphology, serving as the chair of the division of geological sciences from 1952 to 1968 and eventually retiring in 1979. Even in retirement Sharp continued to keep up a busy schedule of field trips and other activities with students and others in the Caltech community interested in geology.

Always concerned with field geology, Sharp led or participated in field trips large and small throughout his lifetime. In 1937 he accompanied a research expedition through the Grand Canyon at a time when the effects of erosion on the geology of the canyon were still little understood. In 1941 Sharp participated in an expedition to study the glaciers of the Saint Elias Mountains on the border between Canada and Alaska. This expedition and others in Alaska provided Sharp with expertise that he drew on during his wartime service to write survival manuals for pilots forced to land in the region. In addition to these large-scale expeditions of his early career, Sharp organized and led expeditions in the Midwest during his time at the University of Illinois and later in the desert regions of California during his long tenure at Caltech.

Sharp’s considerable contributions to science included a variety of studies of terrestrial formations as well as analyses of the surface composition of other planets. His studies of the movement of sand dunes and wind ripples laid the groundwork for further advances in understanding the geomorphology of arid regions. He also published several monographs on the subject of glaciers and glaciation as well as numerous geology field guides. Several of these guides were not written for other scientists but rather for general readers interested in the landforms of the American West.

In terms of Sharp’s contributions to planetary science, he was part of the team assigned to analyze the images sent by Mariner spacecraft from Mars in the 1960s. In fact, the decision to deploy cameras on these early missions to study Martian geology was largely based on recommendations by Sharp and his colleagues. One conclusion that the team drew from its analysis of the photographs produced by various Mariner flights was that Mars probably had had water flowing on its surface at an earlier point in its history. After the final Mariner mission ended in 1972, Sharp published three seminal papers in the Journal of Geophysical Research in 1973 on the sand dunes and other surface features of Mars.

In addition to his direct contributions to science, Sharp was equally important for his administrative and leadership qualities. According to coworkers Clarence Allen and David Stevenson, Sharp’s leadership resulted in two major developments at Caltech. The first was Sharp’s guidance of the program toward an emphasis on geochemistry at a time when more traditional geologists resisted such a change. The second was the choice to pursue research in planetary science, a decision influenced by the existence of the Jet Propulsion Laboratory on the Caltech campus. As chair of the geological sciences division at Caltech, Sharp molded the division into a modern multi-disciplinary research group with varied interests, especially in new applications of the various disciplines to planetary exploration. Researchers at Caltech played an important role in analyzing the samples of rocks and soil brought back from the moon by the Apollo 15 astronauts in 1971.

Sharp was a member of the Geological Society of America, the American Geophysical Union, and an honorary fellow of the International Glaciological Society. He received numerous honors for his lifetime of service to science. In 1950—only three years after returning to teach at Caltech—he was named by Life magazine as one of the ten outstanding college teachers in the United States for that year. In 1978 Caltech honored Sharp by creating an endowed professorship in geology named after him. His other awards include the Kirk Bryan Award for research excellence in Quaternary geology and geomorphology from the Geological Society of America (1964); the Exceptional Scientific Achievement Medal from the National Aeronautics and Space Administration (NASA) (1971); the Penrose Medal, the highest award given by the Geological Society of America (1977); the National Medal of Science, the highest honor given to American scientists in all fields (1989); and the Charles P. Daly Medal from the American Geographical Society (1991). Sharp was elected to the National Academy of Sciences in 1973. In 1978 he was awarded the Distinguished Eagle Scout Award by the Boy Scouts of America.

A memorial tribute to Sharp appeared in Engineering and Science 67, no. 2 (2004). Obituaries are in the Los Angeles Times (28 May 2004) and the New York Times (14 June 2004). Interviews with Sharp were recorded by Graham Berry for Caltech’s Oral History Project in 1979 and 1980 and by Ronald Doel for the American Institute of Physics in 1990.

Todd Timmons

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