Apollo 17 Astronaut Harrison Schmitt (BS ’57) Returns to Campus

Harrison Schmitt (BS ’57) gave a lecture on lunar geology at Caltech on August 4, 2026. Credit: Caltech Astro

One of the last humans to walk on the moon, and the only geologist to do so, delivers a talk on what moon dust can tell us.

By Lori Dajose (BS '15)

Scientist-astronaut Harrison Schmitt is photographed standing next to a large split lunar boulder during the third Apollo 17 Extravehicular Activity (EVA-3) at the Taurus-Littrow landing site. Credit: NASA

Schmitt visits the Division of Geological and Planetary Sciences and poses with a statue of himself modeled after his moonwalk on the Apollo 17 mission. Credit: Cameron Hummels

In 1972, Caltech alumnus and former astronaut Harrison Schmitt (BS '57), the Apollo 17 mission’s lunar module pilot, became the only geologist to walk on the Moon. On August 4, 2026, Schmitt visited campus to give a talk entitled "Apollo 17's History in the Dust." In introducing Schmitt, Caltech planetary scientist Mike Brown described the Apollo 17 mission as “the most epic field geology that’s ever been accomplished.”

Schmitt, who served as a US Senator representing New Mexico from 1977 to 1983 (after 10 years  as a NASA astronaut), outlined how billions of years of lunar history can be understood through the Moon’s isotopic signatures. Studying the chemical composition of the ancient dust in the Taurus-Littrow valley, where the Apollo 17 crew landed, gave clues to how the early moon's magma ocean solidified and differentiated, with heavier minerals sinking into the crust.

During the lecture, Schmitt praised Caltech as a “great field geology institution” and expressed his hope for more field geology training for astronauts in NASA’s Artemis moon exploration program, citing how the benefits of his own such training applied to lunar sample collection. Schmitt also emphasized the importance of combining autonomous robotics with human capabilities, saying that only humans can handle the “unknown unknowns”—surprises on a space mission that can’t be predicted.