On July 20, 1969, while millions of Americans thrilled to the televised sight of Neil Armstrong and Buzz Aldrin walking on the moon, Caltech Professor of Geology Lee Silver, watching TV at home with his family, had his eyes trained on the dust the two men were kicking up.

"I was a Caltech professor getting ready to analyze lunar samples," Silver says. "I wanted to see where the samples were taken." But Armstrong broke protocol and stepped outside the range of the stationary video camera. For 10 extraordinary minutes, Apollo 11’s commander disappeared from Mission Control’s view, gathering 80 kilograms of rocks to initiate what Apollo 15 commander Dave Scott would later call "the meat part" of the Apollo series–the scientific sampling of rocks from the moon’s surface. The 842 pounds of rocks taken by the 12 Apollo astronauts during six lunar landings from 1969 to 1972 would eventually transform planetary science, and questions raised by the lunar samples still roil scientific theory today.

Last November, as part of a presentation for the Caltech Associates, Silver, now the W. M. Keck Foundation Professor for Resource Geology, Emeritus, showed slides from his personal collection and reminisced about his involvement in the Apollo series as geology field instructor to the astronauts of Apollo 13, 15, 16, and 17. That same night, Silver screened an installment of From the Earth to the Moon, HBO’s 1998 12-part dramatic series on the Apollo missions. The hour-long episode showed skeptical Apollo 15 astronauts falling under a crotchety but masterful field geologist’s spell, then going on to triumph during their "final exam"–gathering samples from the lunar surface.

In the following comments, taken from his talk to the Associates and a conversation this summer in his basement office in North Mudd Laboratory of Geology and Geochemistry, Silver touches on Hollywood romanticism versus reality, "the cream" of a lifetime of talented students, and his role in an epochal adventure that began 30 years ago this year.

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[Left] In his basement office in North Mudd, Professor Lee Silver poses with a distant and much younger relative of the "genesis" rock found on the moonÜa mineral specimen from Labrador made up of the major component of anorthosite.

The HBO film depicts Silver as a reluctant curmudgeon, initially annoyed at being tapped by former student Harrison (Jack) Schmitt ’57 to teach a bunch of bored prima donnas. In fact, the professor approached his new students eagerly, having been impressed by Neil Armstrong’s enthusiastic geology work.

I have to say that the actor [David Clennon in the HBO film] did a very fine and romantic rendition of me, but it wasn’t quite the way it happened. When Jack Schmitt first came to me, he’d had a prior discussion with Eugene Shoemaker [chairman of what was then Caltech’s Division of Geological Sciences, who died in an automobile accident in 1997], who asked if I was interested in teaching the astronauts. Then I went to Houston as a lunar sample investigator, and Schmitt arranged a meeting with Jim Lovell [commander of the ill-fated Apollo 13 mission]. After we discussed a possible training effort, Jim said to me, "Well, I’ll give you a week, but if it doesn’t work, we’ll do something else."

The performance of Apollo 12 in November 1969 confirmed the missions’ improved orbital mechanics and pinpoint landing capability, setting the stage for some serious scientific work. Meanwhile, in late September 1969, Silver had had his week with the Apollo 13 landing crew, Jim Lovell and Fred Haise, and their backups, John Young and Charlie Duke, who would later fly on Apollo 16. Jack Schmitt and a field assistant completed the party. Silver’s goal was to convince the astronauts that doing geology fieldwork was worth precious training time.

During the ’60s, these guys were introduced to field geology but tended to be snowed with geological terms. I said, we don’t need any special jargon, we need to use exactly the same language you’d use as a test pilot. We were looking for documentation, interesting samples, an overview of the environment, in clear and simple language, ordered and organized. I was gently trying to show them that they were such acute observers, and such well-educated men, that if they bent their intention to this purpose they would produce useful results that would enhance their missions. These guys would have been the generals and the admirals of the military services, the top test pilots. They were all just absolutely the cream.

For the astronauts’ first outing, Silver loaded up one Caltech vehicle with equipment and another with his charges and drove to the Orocopia Mountains in the Southern California desert, where he had often trained Caltech students. He then let the beauty of the setting and the astronauts’ natural curiosity work their magic.

We didn’t have any tents, we had cots, and everybody brought their own sleeping bags. At the beginning of each day, I laid out the day’s exercises. At the end of the day, the "professor" would review with the troops just what they had done that day, go through the rocks they had collected, make comments. At the very end of each day, I had to cook dinner. They did the dishes.

In the field, we used a tree as our landing module [the spacecraft that during the mission would disengage from the larger command module, which would remain in orbit, and land on the lunar surface]. In the film they were sitting in the shade. I never allowed anybody to sit in the shade.

Due to an explosion en route, Apollo 13 never made it to the moon, but did return to Earth safely with its crew. It was Silver’s later, 15-month training period with the Apollo 15 astronauts, and that crew’s brilliant geological performance on the lunar plain between the Apennine Mountains and Hadley Rille, a sinuous gorge, that, in Silver’s words, "hit a home run." By then, Silver had learned a few things himself.

This time I was a little smarter, a little older. I had learned from Apollo 13 how much these guys had to do. I had to worry about all their constraints, to look at the expectations with equipment, with time, with the suits, the durations of the EVAs [extra-vehicular activity, or excursions outside the landing module], etc. I had to learn what science was being done by hundreds of investigators, which would in turn influence the planning for what we did next. The whole lunar exploration was a growth phenomenon. As the missions became more complex (e.g., utilizing the lunar rover), NASA was extending the launch schedule, so that the training became more and more extended, and that was very helpful.

As the training period expanded, the Apollo 15 geology field trips crisscrossed the country, evolving from exercises into simulations with dozens of scientists and NASA personnel participating. The entire staff of the geology "back room" at Mission Control (the room where the scientists would be monitoring the astronauts’ actions during the actual mission) normally came along for the ride. And, for the first time, the astronauts trained with the four-wheeled vehicle they would ride in on the moon to cover more territory and collect a wider variety of geological samples. It was a time of intense activity for Silver.

I was like a person going into battle. For 15 months, I was running exercises in different parts of the country, training the astronauts in different aspects. I was still doing my samples for my lunar analyses, and I taught all my Caltech courses. I was in one mad whirl, trying to meet all the challenges. The crews were telling me what they could do and what they couldn’t do. I had to learn from them and still manage to push what they could do on the surface. There were an infinite number of things I couldn’t get to, because there wasn’t enough time, but you did what you had to do. Do soldiers go into battle perfectly trained? No, they don’t–the battlefield is the final training ground.

Earlier lunar landing sites had been selected in part for their flat, straightforward topography that lessened the chances of landing mishaps. But the growing confidence in the astronauts’ navigating skills and their landing modules’ maneuverability enabled Apollo 15’s planners to choose a landing site at the base of the moon’s Apennine Mountains, which rise more than 15,000 feet above the Hadley Plain. The site was more than just visually spectacular; the moon’s peaks were presumed to consist of older geologic material than its flat areas, and some scientists thought that rocks gathered from the mountains’ periphery might date from close to the time of the moon’s origin. Prior to Apollo 15, components of a rock called anorthosite, found on Earth, had been detected in previously collected lunar samples, but no complete specimen had turned up. Apollo 15 astronauts Dave Scott and Jim Irwin had learned to identify anorthosite while on a field trip with Silver in the San Gabriel Mountains, in Caltech’s own backyard. Now, at the Hadley Delta, at 10 a.m. on Sunday, August 1, 1971, Scott and Irwin would find the "genesis" rock, a chunk of anorthosite that had apparently originated in the moon’s primordial crust, leading scientists to propose a now widely held theory that billions of years ago, a Mars-sized body collided with Earth, giving rise to the moon. Estimated to be 4.5 billion years old, the fist-sized rock remains the most primitive (i.e., least evolved) sample yet taken from the lunar surface. Although lionized by the media, the find was only one instance in a brilliant interval of field geologizing that Silver would subsequently characterize as "hitting a home run." Two days later, en route back to Earth, the two astronauts made the unprecedented request to speak directly with their professor, who was in the back room at Mission Control. It was 4 a.m. Houston time, but Silver was up, "doing geology." "We’ll have to get you up here," Scott said to Silver, who in turn congratulated Scott and Irwin on their outstanding field work.

It was the only time that anyone in the back room other than the capsule communicator [who spoke on behalf of Mission Control to the astronauts] had ever spoken directly to the command ship. That was very rewarding. I had a sense of being honored by them, in that moment. Did I break down and cry? Hell, no. I was so glad to hear them. They were on the way home. They were close, and I was so glad.

In a highly romanticized flashback, HBO’s aging Professor Silver muses longingly about how it might have been to wander the moon’s surface for 25 years, sample bag and coffee thermos in hand. The real Silver did not have script approval.

Those weren’t my words. I’m a field geologist, but I also ran–it’s closed down now–a sophisticated isotope chemistry lab, and I was interested in the samples and what one could get from doing analytical work in the laboratory. I would have been happy to have been up there, but not for 25 years. I would have wanted to come back and analyze my samples, and to bring back samples for other people to work on. The wonderful thing about the Apollo missions was the fantastic array of talent. The crew made an enormous variety of measurements, and we understood the samples we analyzed in a way we’ve never ever done with terrestrial samples, because we’ve never invested that much money in supporting investigations of that kind here on Earth.

After Apollo 15, Silver handed over the major responsibility for astronaut-training duties to other geologists, including Caltech alumnus Bill Muehlberger ’49, PhD ’54. In December 1971, Silver’s former Caltech geology student, Jack Schmitt became the first professional scientist to visit the moon, as lunar module pilot on Apollo 17, the final flight in the series. Silver’s close association with the astronauts of Apollo 13, 15, 16, and 17 remains an unforgettable highlight in a long and distinguished career.

You know that Captain Cook was a great 18th century explorer. [Apollo 15 Commander Dave Scott named his command module Endeavour after Captain Cook’s maiden ship.] On his first expedition Cook took along a very wealthy English aristocrat by the name of Joseph Banks, who had an interest in things scientific. Banks wrote a book about the voyage that made a valuable contribution to our knowledge about the flora and fauna of the part of the Pacific that they explored. He later became president of the Royal Society because of the reputation he obtained riding along with Captain Cook. Well, I was a sort of poor man’s Joseph Banks, along with about two or three hundred others. I had an opportunity to participate in a great expedition.

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For further information, Hollywood-style, about Lee Silver and lunar geology, check out HBO’s video From the Earth to the Moon (Part 10: Galileo Was Right). Also entertaining but less romanticized is Andrew Chaikin’s book about the Apollo series, A Man on the Moon, published in 1994 by Viking Press.

By Marcy Drexler