Skip to Main Content

Geological & Planetary Sciences: Caltech and the Apollo Program

Caltech and the Apollo Program

As Apollo 11 launched from Cape Kennedy on July 16, 1969 on its way to landing the first men on the moon, among the spectators was novelist Herman Wouk—who was inspired to send a postcard to his brother, Caltech alumnus Victor Wouk (MS ’40, PhD ’42), noting that “nothing can trivialize this awesome thing.”

Herman Wouk postcard to Victor Wouk (Victor Wouk Papers, folder 67.1)


Four days later, Neil Armstrong and Buzz Aldrin landed on the moon. They completed their mission on July 24 when they returned to earth. On July 25, Caltech’s President Harold Brown sent a congratulatory letter to NASA administrator Thomas O. Paine, commenting:


"I am sure that [Apollo 11] will be followed by many other feats, both in terms of adventure and in terms of the understanding of the universe around us. But the first manned lunar landing will always remain the largest single milestone in the exploration of the solar system."

 (Harold Brown Papers, folder 17.1)

But landing a man on the moon was only part of the mission. The astronauts were to collect and return with lunar materials.

Neil Armstrong, from glass plate photograph collection in Gerald Wasserburg Papers (folder 165.1)


Over a two-year period, approximately 140 scientists from around the world were selected by NASA to receive lunar samples. Among them were six from Caltech:

Gerald J. Wasserburg, geology and geophysics
(Principal Investigator, lunar sample program)

Leon T. Silver, geology
(Principal Investigator, lunar sample program)

Samuel Epstein, geochemistry
(Principal Investigator, lunar sample program)

Clair C. Patterson, geochemistry

Donald S. Burnett, nuclear geochemistry

Hugh P. Taylor, Jr., geology

Silver (PhD ’55) and Patterson were to measure amounts of the radioactive elements uranium and thorium, which decay at known rates into forms of lead, thereby determining the age of the rocks as well as possibly dating any volcanic activity and any heat produced from the decay.

Epstein and Taylor (BS ’54, PhD ’59) were to search for isotopes of oxygen, hydrogen, carbon, and other elements to determine the temperatures at which moon minerals were formed, as well as any possible interactions between the rocks and water that might exist on the moon.

Wasserburg and Burnett would, in Wasserburg’s words, “watch the abundances of certain elements in the lunar material with regard to implications about the origin of the moon, the earth and meteorites.” Their analyses would include looking for traces of such chemical elements as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, gadolinium, and rare gases such as helium, neon, argon, krypton, and xenon.

A seventh Caltech scientist, Geology Division chair Eugene M. Shoemaker (BS ’48, MS ’49), was Principal Investigator of the field geology program. That summer, immediately following the astronauts’ return, Shoemaker and Wasserburg left for Houston to be advisers at the Manned Spaceflight Center’s Lunar Receiving Laboratory (LRL), where the samples were quarantined and underwent preliminary examination. Earlier, Shoemaker and Silver had trained the astronauts to perform field geology.

(Leon Silver discusses Shoemaker, the Apollo program, and astronaut and Caltech alumnus Harrision H. “Jack” Schmitt (BS ’57) in his oral history interview , pages 42–53, available online. For more on preparing astronauts as geologists, see “ Geology on the Moon ” in the November 1971 issue of Engineering and Science .)

Leon Silver with Apollo 15 astronauts in the San Juan Mountains of Colorado, 1971


On the Caltech campus, five new laboratories were constructed in the North Mudd and Arms buildings to receive the lunar samples in an antiseptic environment, free of dust and lead. Wasserburg and his graduate student Dimitri Papanastassiou (BS ’65, PhD ’70) developed what came to be known as “Lunatic I,” the first fully digital mass spectrometer, enabling them to measure isotope ratios with 30 times the precision of earlier instruments. Wasserburg’s lab on the second floor of Arms would become known as the “Lunatic Asylum.”

Lunatic I in Wasserburg’s lab, 1978


On September 8, 1969, NASA administrator Thomas O. Paine wrote President Brown to discuss the future delivery of the lunar samples to Caltech and their proper handling, adding that “loss due to carelessness or for any reason, including theft, would be inexcusable.”

Thomas O. Paine to Harold Brown (Harold Brown Papers, folder 7.3)


Once the materials were received at all participating institutions, a deadline was set for January 1970, when the 140 scientists would arrive in Houston and report their preliminary studies. A summary of Caltech’s findings by Wasserburg, Epstein, and Silver was reported as “ Research Notes ” in the January 1970 issue of Engineering and Science .

Moon rocks, from glass plate photograph collection in Gerald Wasserburg Papers (folder 165.1)


With Caltech’s participation in the Apollo lunar sample program, as well as previous work in space sciences—beginning as early as 1961 with then research fellow Bruce Murray (and future JPL director, 1976 to 1982)—in December 1970 the Division of Geology decided to change its name to Division of Geological and Planetary Sciences.

Caltech would continue its involvement with the Apollo program through December 1972, when Harrison “Jack” Schmitt (Caltech BS ’57), who NASA had selected as its first scientist-astronaut in 1965, served in the last manned Apollo mission, Apollo 17, with Eugene Cernan.

In a June 28, 1972 letter sent to Schmitt, Wasserburg wished Schmitt well, and wrote, “we look forward to your having a very exciting and valuable trip and will have the wine all ready, if you will be willing to swap it for rocks.… I look forward to a successful mission for the last of the Apollo generation.” (Gerald Wasserburg Papers, folder 27.28)  LK, July 2019