posted 09-04-2026 07:19 PM               

Don Wilhelms, a pioneering planetary scientist known for producing some of the earliest geologic maps of the moon, passed away this morning in Palo Alto at the age of 96. During his time at the USGS, Don worked closely with Gene Shoemaker and, among many notable achievements, helped train the Apollo astronauts. Details of a memorial service will be announced at a later date.

Above: Don Wilhelms (at left) with a group of Apollo astronauts in the control room of the McMath-Pierce Solar Telescope (MMP) at Kitt Peak National Observatory (KPNO) in 1964. Left to right: Donn Eiseie, Wilhems, Spencer Titley (University of Arizona), Ray Zedekar (NASA), Theodore Freeman, Frank Borman, Gene Cernan and Harold Masursky (USGS). (United States Geological Survey)

Excerpt from a biography prepared by Mary G. Chapman for the USGS in 2002:

In 1962, the space program was really getting started. A friend told him that someone - Gene Shoemaker - was over at Caltech interviewing people for jobs in lunar geology with the USGS. Don got an interview with Gene.

During the interview, Gene and Don discovered mutual interests in astronomy, Quaternary geology, geologic processes, and non-uniformitarianism, but Don did not receive a follow-up letter. This job, combining his old love of astronomy with his new immersion in geology was the only thing in life that Don really knew for certain that he wanted. He wrote Gene, restating his interest. Gene started the paperwork to hire Don in 1962.

When Don was hired by the USGS, he was still writing his dissertation. Friday, Nov. 30, he turned in his dissertation, and drove to Menlo Park to begin work on Monday, Dec. 3, 1962. He was awarded his Ph.D. degree from UCLA in 1963.

After six months mapping the moon using the telescope at Lick Observatory, Shoemaker sent Don to Paris to study polarization as a technique for interpreting lunar geology with Audouin Dollfus. Polarization was supposed to show the structure of the lunar surface soil, but proved little except that it correlates with surface albedo (relative brightness). ...

Don went on to live in Houston for a year to participate in astronaut instruction. He returned to Menlo Park and became deeply involved in the Lunar Orbiter and Apollo Programs, notably landing-site selection. His career evolved to include studies of Mars, Mercury, and Ganymede. He retired from the USGS in 1986.

In retirement, he has been occupied with completing maps of Ganymede, studies of the martian highlands, and writing the book "To a Rocky Moon." Of his many scientific accomplishments, Don feels the high points of his career were providing the overviews of the history and findings of lunar exploration in "To a Rocky Moon" and "The Geologic History of the Moon."