A video recording from the NASA archives starts like this: Apollo 16 astronauts Charles Duke and John Young are ambling across the moon. Young moves about in the background, while Duke takes two little hops toward a gray, lumpy rock near the rim of a crater.
“This one right here?,” Duke asks to Mission Control as he approaches the rock, carefully scooting closer and closer to the crater’s edge. “That’s it. You got it right there,” a voice from Mission Control confirms.
The rock is bulky and easily visible even on the grainy footage. And when Duke bends down to collect it, he audibly heaves as he hoists it up with his one free hand.
“If I fall in the Plum Crater getting this rock, Muehlberger has had it,” Duke says in a miffed tone as he walks off with the rock and the clip comes to a close. (You can watch the scene for yourself at: http://ow.ly/Vs1N50vLnh6)
The Muehlberger he’s referring to is UT geology Professor William Muehlberger, who served as the principal investigator for field geology for the Apollo 16 and 17 moon missions. He taught the astronaut crews how to conduct field work on the moon by practicing at sites here on Earth. And for his service — or perhaps insistence that the astronauts lug the rock back to Earth — the sample collected on the Plum Crater’s edge was named “Big Muley” in his honor. Weighing in at 26 pounds, it ended up being the heaviest rock brought back from the moon.
But Muehlberger wasn’t the only geoscientist from The University of Texas at Austin involved with historic moon missions. And the impact of UT geoscientists on training astronauts didn’t end with Apollo. As we honor this year’s 50-year milestone of Apollo 11, the first mission to land on the moon, get to know the UT geoscientists who were part of history then, and those who are making it now.
For nearly four decades, Jackson School of Geosciences Professor William Muehlberger took geology undergraduates from UT into the dry desert mountains of West Texas as part of the school’s annual summer field camp. The cragged formations were a testament to the power of tectonics, while the shifts in stratigraphic layers showed how the geology of different eras built the landscape of today.
In April 1964, Muehlberger taught similar lessons to a class of a different sort of students: Apollo astronauts. His charges included Buzz Aldrin and Neil Armstrong — the men who would make history as the first humans to walk on the moon.
After planting the American flag, the most important objective of astronauts on the moon was field geology. From the very beginning, astronauts were sent up with seismic sensors and came back laden with rock and soil samples. However, the astronauts of the Apollo program were test pilots, not rock hounds (the only exception being Harrison “Jack” Schmitt, a professional geologist and the only scientist to walk on the moon). To get the astronauts up to speed on the fundamentals of field geology, NASA depended on local experts who taught geology lessons that astronauts could learn on Earth and apply on the moon.
In the Marathon Basin of West Texas, NASA turned to Muehlberger to be that expert. It would be the start of a collaboration with NASA that would outlast the Apollo years and would position the Jackson School as a leader in teaching geology to astronauts.
Muehlberger was known for his work on tectonic processes at the regional and continental scales. In 1968, the year before the moon landing, he directed the production of the U.S. Geological Survey’s first edition of its Basement Rock Map of the United States. Although the astronauts were just neophytes when it came to that type of work, Muehlberger said that what the astronauts lacked in formal knowledge they more than made up for in enthusiasm.
“What I found is that teaching geology to astronauts is fun!” Muehlberger wrote in a 2005 article for Geotimes magazine. (now Earth). “They are smart and interesting people, and while most have little or no knowledge of geology, they all want to learn.”
Neil Armstrong, for one, considered the time in the field as time well spent.
“I enjoyed geology, and it was certainly appropriate to understanding what we were seeing on the surface of the moon,” he said in a 2002 interview with the Johnson Space Center (JSC) Oral History Project. “Had I been a better geologist, I might have seen some things that were important that I missed … but in the time that we had available, I think everyone did a credible job of being able to see things that were important and know which samples to pick up and be able to describe to people back on Earth what they were seeing.”
After the Marathon Basin field training, Muehlberger returned to UT, where he became chairman of the Department of Geological Sciences in 1966. But he never lost touch with NASA and the Apollo happenings. He got the latest news on lunar geology from fellow UT geology Professor Hoover Mackin, who worked withcNASA developing hand tools and sampling procedures, and who covered his office walls in hand-colored copies of geologic maps of the moon. Muehlberger also helped NASA make a moonscape of its own by arranging for a 16-ton dump truck to deliver granite from the Llano Uplift to the Kennedy Space Center in Florida. Then, six years after the Marathon Basin field exercise, Muehlberger found himself teaching astronauts again when NASA asked him in 1970 to serve as the principal investigator for field geology for Apollo 16-20, the final missions.
“Holy Toledo. I knew that the moon was up here on this wall, but that was about it,” Muehlberger said in the JSC Oral History Project, recounting his reaction to being offered the job and referring to Mackin’s moon maps. “And here I am suddenly the head man.”
The Apollo program ended up lasting only through Apollo 17, with Muehlberger serving as principal investigator for the final two missions, as well as for the Apollo 15 backup crew. In interviews and articles, Muehlberger calls these final three missions the “big science” missions. They involved exploring more complex terrain, using a moon rover to go longer distances, and deploying new sampling technology — such as a coring drill developed by UT alumnus Uel Clanton. Apollo 17 even brought a bona fide geologist, astronaut Jack Schmitt, to the lunar surface.
As principal investigator, it was Muehlberger’s job to plan the geological traverses that astronauts would take on the moon and prepare the crew to execute them. Doing that involved taking field trips to lunar analogs on Earth — the lava fields of Hawaii and Iceland and the craters and gorges of the southwestern United States, for instance — but interacting with the astronauts as if they were already on the moon.
Muehlberger and his team would stay out of sight, available only through radio contact, as the men ambled along their traverses carrying packs bulked up with Styrofoam and with tools placed as they would be on the real mission. A local geologist would shadow the crew on their mock missions, providing feedback to both the astronauts and the geology team once the traverse was over and everyone presumed to be back on their home planet.
By the time the astronauts on the “big science” missions went to the moon, Muehlberger estimated that they each had the equivalent of a master’s degree in geology. Their extensive training was put to the test when the crews of both Apollo 16 and Apollo 17 encountered geology that they were not expecting.
Instead of volcanic rocks, the Apollo 16 crew found that the Descartes Highlands were dominated by beaten-up breccias, the result of meteorites bombarding the moon earlier in its history. During this mission, the astronauts also found Big Muley — the biggest rock ever brought back from the moon, and named by the astronauts in Muehlberger’s honor. The geologists at Mission Control spotted the rock on a live-feed that the astronauts set up, and they had high hopes that it was a chunk of the lunar crust. But it was just another breccia.
From their geology training, the astronauts at least knew that the lack of volcanic rock wasn’t an oversight on their end. Although it took a minute to convince the geologists in Mission Control.
“We kept looking for ilmenite and all those little crystals in the basalts, but we didn’t see any basalts and no ilmenites, and everyone got mad at us,” said astronaut John Young in a 1995 interview cited in a NASA document on the history of the science training of the Apollo astronauts.
As for the crew of Apollo 17, they ended up finding some of the oldest rocks sampled on the moon in the place where the NASA geologists thought they would find the youngest. The geologists had interpreted the dark landscape as a sign of youth, the thought being that meteors had not had time yet to pound it into a lighter gray hue. But it turned out to be material forged billions of years ago in the moon’s mantle.
The moonscape being so different from what was expected only proved to Muehlberger the importance of conducting geological field work in the first place, he said in an interview with the JSC Oral History Project.
“That’s why you go and check. You can’t interpret these photographs 100 percent right all the time,” he said. “It would be nice if you could,” he added, but then quickly took it back. “No, it wouldn’t because it’s more fun going out and looking … That’s what geology’s all about, going to find out what you [were] really supposed to learn there.”
The value that Muehlberger put on from-the-ground interpretation is illustrated by how he oversaw field work on the final moon mission, Apollo 17. Instead of sticking to objectives planned 238,000 miles away on Earth, he deferred to Schmitt, the geologist on the moon. Muehlberger knew that NASA would not officially approve a flexible field work schedule, so he kept the official task list for show while the actual objectives were set by Schmitt in the moment.
“In effect, he was running the mission from the moon. I was the official one. But what the heck? I can’t see that stuff like he can,” Muehlberger said in the JSC Oral History. “All of those within the geological world certainly knew it, and I had a sneaking hunch that the top brass knew it too, but this is a practical way out, and they didn’t object.”
The return of the Apollo 17 crew ended the era of lunar geology field work by astronauts as NASA shifted its sights toward studying the Earth. Muehlberger’s expertise in large-scale tectonic processes made him an asset to astronauts who were now tasked with observing their home planet, first from the space station Skylab, which flew from 1973 to 1979, and then aboard the Soviet spacecraft Soyuz during the Apollo-Soyuz mission of 1975. For these missions, Muehlberger taught global tectonics using aerial photographs of rift valleys, faults and mountain ranges. However, it wasn’t long until he was again in the field with astronauts. Before the launch of the first space shuttle in 1981, he met with astronaut Sally Ride, who would become the first American woman in space, and they decided that the crew would benefit from a visit to the geological features that they would be observing from orbit.
That decision led to NASA rebooting field geology training for astronauts under Muehlberger’s leadership. He ended up leading most of the space shuttle crews on four-day field trips through the geology of northern New Mexico.
Spending all that time with astronauts may have inspired Muehlberger to see the Earth from orbit himself. In the JSC Oral History, near the closing of a long conversation, he revealed that he applied to be an astronaut during the space shuttle program but was not selected. Nevertheless, he frequently wore a memento of the shuttle’s first flight — a bolo tie of New Zealand jadeite that commander John Young brought along into orbit.
Muehlberger died in 2011, the same year the space shuttle program ended. But the training of NASA astronauts by members of the Jackson School continues. Researcher Patricia Dickerson and Distinguished Senior Lecturer Mark Helper have broadened the content and expanded upon the foundation first laid by Muehlberger. Both have guided astronauts in field training exercises and have taken part in organizing a network of geoscientists who are up to the challenge — and excitement — of teaching astronauts how to explore their world and others.
The zig zagging lines of data served as a signal for Yosio Nakamura, now a Jackson School Professor Emeritus, and the rest of the Apollo Passive Seismic Experiment team to gather at the Manned Spacecraft Center (now the Johnson Space Center). It was their job to learn about the moon’s interior by interpreting the seismic data.
“It was such an exciting time,” said Nakamura, who is also a researcher at the Institute for Geophysics (UTIG). Nakamura’s involvement with the seismic experiment started in 1967, when he took a one-year leave of absence from his job at General Dynamics in Fort Worth to conduct postdoctoral research with renowned geophysicist Maurice Ewing, the then-director of Columbia University’s Lamont-Doherty Geological Observatory. He wasn’t expecting to work with Ewing on lunar seismic research, but when Ewing was asked by NASA to take the lead on the project, Nakamura became part of the team, which was led by Ewing’s former graduate student Gary Latham.
By the time of the moon landing, Nakamura was back at General Dynamics. During the Apollo years he balanced his day job there with NASA lunar research.
The goal of the first seismometer was to listen to the background noise of the lunar surface, such as meteoroid impacts. This passive listening that gave the experiment its name went on for about 21 Earth days (1½ lunar days) until it shut down due to overheating. But that was just the start of seismic research on the moon.
New seismometers — now equipped with heat shields — were installed by astronauts with each following mission that made it to the moon. The seismic experiments became bolder, too. Astronauts set off charges and crashed lunar modules on the moon’s surface as they departed for Earth.
Nakamura and other scientists learned about the interior of the moon by studying how the seismic signals that originated on the lunar surface changed as they travelled through the moon’s subsurface. But no one expected to record signals coming from within the moon itself.
“Before we went there, just about everyone thought nothing was happening inside the moon,” Nakamura said. “But at least signals from meteors hitting the surface could maybe tell us something about the moon’s internal structure.”
The assumption of a geologically dead moon turned out to be wrong. The seismometers picked up moonquakes — seismic signals generated by rocks shifting and moving within the moon. However, the signals from these quakes were initially a mystery. It took until Apollo 15, in 1971, for the researchers to have enough seismometers on the lunar surface to confirm that the mystery signals were coming from deep inside the moon.
Once the geophysics team knew what to look for in a moonquake signal, they were able to pick them out on the earliest readings from the Apollo 11 seismometer and even distinguish between different types of quakes. They found deep events occurring just about half way to the center of the moon.
They also detected much larger events occurring close to the surface but far from the seismic stations.
“We called these high frequency teleseismic events, now called shallow moonquakes,” Nakamura said.
Still, today little is known about shallow moonquakes and why they occur, Nakamura said. An idea he developed with UTIG colleague Cliff Frohlich, a research scientist emeritus, was that they may be triggered by something coming from outside our solar system.
“They seemed to occur at certain times when the moon was facing a certain direction, not relative to the sun, but the stars,” Nakamura said. “This is only our guess, but maybe shallow moonquakes are caused by particles hitting the moon from some far away star.”
Deeper moonquakes have less mysterious origins. Scientists have linked them to changes in the gravitational pull on the moon as it orbits the Earth and sun.
During Apollo, all the data from scientific instruments on the moon was transmitted live to Earth and recorded on large, seven-track digital tape reels. Each reel stored about 800 bits per inch — about the same amount of data as a JPEG image file. NASA struggled for years to manage the thousands of reels generated by the lunar experiments until, in 1976, NASA eventually decided it had had enough. Officials reached out to researchers at the Galveston Geophysics Laboratory at the University of Texas Marine Sciences Institute, the precursor of UTIG and where Nakamura was now working, to see whether the university could serve as the scientific home for the last leg of incoming lunar data. For the final 19 months of lunar readings, Nakamura took part in receiving, processing and recording of not just the seismic data, but data from all scientific instruments making measurements on the moon.
Since then, Nakamura has become a lunar archivist who not only is analyzing seismic data, but saving it. Thanks to his efforts, UTIG maintains copies of the Apollo program’s seismic data, along with the final 19 months of lunar instrument readings. Nakamura has also led the charge in keeping the data accessible. In the early 1990s, Nakamura hired a team of undergraduate UT geosciences students to copy all 12,000 tapes onto just 80 cassette tapes — an effort that took about a year and a half. And he has since ensured that all the Apollo lunar data are safely stored in an online and public-access database so that a new generation of scientists — and a new generation of data-analysis technology — can continue to mine them for new discoveries.
The effort has already resulted in amazing new finds. For example, Nakamura and Texas Tech Associate Professor Seiichi Nagihara, who earned a Ph.D. from the Jackson School, uncovered and incorporated an additional 440 reels of scientific data covering a three-month period from April to June 1975. It took many years to find funding and equipment to extract the data from the reels, but finally, in 2018, Nagihara published a remarkable paper in the Journal of Geophysical Research: Planets showing that dark moon dust kicked up by astronauts walking on the moon had actually warmed the moon’s surface several degrees.
Nakamura said that he is hopeful that future generations will return to the moon and uncover more of its secrets using seismology.
“I think eventually an international team will go there and put seismometers on the moon again,” Nakamura said. “In this kind of thing, there is no boundary between countries.” In honor of his many lunar accomplishments, Nakamura was inducted into the Jackson School’s Hall of Distinction in 2013.
Additional reporting by:
In 1964, 29 Apollo astronauts — all vying for the chance to go to the moon — filled the room of their first geology course. According to a NASA history on Apollo astronaut training, they were asked this question: “Who has, at some time in their education, taken at least an introductory course in geology?”
Not a single person raised his hand. It was going to take some serious training to get the men ready for the geological field work they were expected to conduct on the moon. In the early days of the Apollo program, UT alumnus Uel Clanton played a primary role in determining what a moon-bound astronaut should know about geology on a world where no human had been before.
Clanton was still a graduate student at UT when he was hired by NASA to develop a geology training program for Apollo astronauts. He was recruited for the position by fellow UT geology graduate and NASA scientist Curtis Mason. But when Clanton arrived at NASA’s Manned Spacecraft Center (MSC, for short and now the Johnson Space Center) in Houston in 1963, he found that he and Mason were in the minority when it came to teaching astronauts to do geology — or really any scientific activities.
“There were only two or three people at MSC at the time who were really thinking or planning any sort of a science-type activity on the moon,” Clanton recounted in the NASA history. “I rather vividly recall one of the earlier conversations with people really high in the structure where the suggestion was made that one might want to pick up some rocks from the moon and return them. And the question was, ‘Why?’”
By the time the first class of Apollo astronauts was selected for training in 1964, Clanton and others had made a convincing case. General geology took up the bulk of training and consisted of six distinct sections. At 58 hours, the first geology section alone outnumbered all other scientific training in terms of time. (The 40 hours of flight mechanics took second place.) The training also included field geology excursions to observe geologic formations in their natural environment. The first of these was a two-day trip to the Grand Canyon.
Clanton had championed the Grand Canyon as the first field experience not because of its direct likeness to lunar geology — no one expected to find a river-eroded gorge on the surface of the moon — but because of the overarching lessons it taught about geology. According to Clanton, the trip was an eye-opening experience for the astronauts, many of whom couldn’t quite grasp why geology was taking up so much of their training time.
“After the first field trip their comment was, ‘well, we’ve listened to you for two weeks and not understood. And one field trip has shown us the importance and the reasons for all of the discussion,’” Clanton said in the NASA history.
In addition to classroom lectures, the Apollo missions also included mission-specific training. Due to time constraints, the crew of Apollo 11 — the first to land on the moon — had time for only a single trip: a rock-sampling excursion in the Quitman Mountains of West Texas. As with most of the other Apollo field trips, Clanton was there as a geology instructor. But on this trip, he also played enforcer against the news crews that were swarming the usually remote mountains for a chance to chat with the moon-bound astronauts. He stopped the reporters in their tracks by using an ax to draw a line in the ground and warning of serious consequences to anyone who crossed it.
The rock-sampling lessons proved successful, with the Apollo 11 crew bringing home just shy of 50 pounds of rocks. These rocks greatly informed lunar scientific training going forward. But in the years leading up to that mission, Clanton had to decide what the astronauts should know about mineralogy and petrology when no one had ever seen a single verified moon rock. (Meteorites that came from the moon were not positively identified until after the Apollo program.) Based on the moon’s reflectivity, scientists expected most moon rocks to be dark, a hypothesis that turned out to be true. But focusing on dark-colored samples could complicate the astronauts’ introductory lessons, as features would be difficult to see.
To avoid these issues, Clanton opted to train the astronauts in geology foundations, teaching basically the same mineralogy and petrology course that he had given to sophomore geology students as a teaching assistant while in graduate school at UT. He even repurposed the old lab manual and persuaded the UT geology department to donate a hand specimen tray used in the class to the Apollo program. This tray served as a reference for 100 more trays put together by NASA.
Clanton also saw to it that the collection represented the landscapes the astronauts were learning from, typically bringing back 30 to 40 pounds of rocks from each field excursion locale to have cracked into hand specimens for teaching.
“If a question came up during the classes about rock types from the localities that had been visited on field trips, one could go to the reference collection and pull out a specimen of whatever weird and wonderful rock that you wanted to talk about,” Clanton said in the NASA history.
With the success of Apollo 11 and subsequent missions, knowledge about lunar geology sprang forward. Astronauts no longer had to depend entirely on suspected Earth analogs for moon rocks when they could learn from the real things. This prompted NASA to reorient incoming astronauts’ geology training toward mission-specific information and skills. Classroom training was cut from about 225 hours to just 35, with astronauts spending more time in the field conducting dryruns of lunar traverses.
Clanton stayed involved with the astronaut training by taking part on mission field trips. He also continued to play an important role in the Apollo program by helping develop geologic tools that astronauts could properly wield while suited up on the lunar surface, including a coring drill, rake and scoop. Clanton would test the tools himself by donning a space suit and trying them out on the infamous “vomit comet” — the KC-135 Stratotanker airplane used to simulate low gravity environments. The tools eventually made their way to the moon on various Apollo missions, where astronauts put them to work collecting moon rocks to bring home.
Maurice Ewing — the founding director of the institutions that would become the University of Texas Institute for Geophysics (UTIG) and Columbia University’s Lamont-Doherty Earth Observatory — spent his career exploring the great unknown of Earth’s ocean geology. He was the first to conduct explosion seismology at sea; he invented the world’s first deep-sea camera (which collected photos of sand ripples and other formations that proved the existence of deep-sea currents); and he was the co-builder of the first mass-produced seismograph, aptly named the Press-Ewing after its two inventors. (Frank Press was a graduate student of Ewing’s at Lamont.)
So, it should come as no surprise that when NASA needed a seismometer that would work on the moon, they went to Ewing. The call came in 1965 when Ewing was director of Lamont Doherty.
Ewing accepted the challenge — but gave the role of principal investigator to graduate student Gary Latham. Postdoctoral researcher Yosio Nakamura also joined the research team.
The resulting instrument was about the size of a shoebox and designed for passive listening — recording the sounds of the natural lunar environment, such as meteoroid impacts. The device provided the first look into the moon’s internal structure through data beamed back to Mission Control in Houston. But the data were short lived: after 1½ lunar days (21 Earth days) the seismometer overheated and died.
However, that was far from the end of seismic research on the moon. In just a few short months after the Apollo 11 crew returned to Earth, Apollo 12 went to the moon and installed a new seismometer. Ewing served as the co-head of the second seismic experiment. Instead of just passively listening to the sounds of the moon, this experiment involved listening as the departing astronauts intentionally crashed the lunar module into the surface of the moon to create a controlled seismic blast. (The Apollo 12 crew was safely aboard the command-and- service module that would take them back to Earth.)
Nakamura said that the impact of the module created a seismic signal unlike any that he had ever seen. It lingered, reverberating within the interior of the moon. The unusual behavior prompted Ewing to make a statement at an Apollo 12 press conference on Nov. 20, 1969.
“It’s as though one had struck a bell, say, in the belfry of a church, a single blow, and found that the reverberation from it continued for 30 minutes,” Ewing said.
Except the signal lasted longer than that. The reverberations were ongoing as Ewing gave his statement and ended up lasting for another 25 minutes. The moon had rung for a full 55 minutes. Researchers later linked the ringing effect with the bone-dry geology of the moon, which helped the sound reverberate among the rocks.
In 1972, Ewing moved back to his home state of Texas to found the Earth and Planetary Sciences Division of the Marine Biomedical Institute at the University of Texas Medical Branch in Galveston — a precursor of what would become UTIG. He died just two years
later in 1974.
The legacy of training astronauts in field geology started by Professor William Muehlberger continues at the Jackson School thanks to the effort of researcher Patricia Dickerson and Distinguished Senior Lecturer Mark Helper.
Dickerson was one of the driving forces in forming the Field Exploration Analysis Team, a group dedicated to recruiting experienced field geologists who could help NASA prepare astronauts for future field work on the moon or Mars. She started the program with Muehlberger, who was her Ph.D. adviser, and astronaut geologist Harrison “Jack” Schmitt in 2006. Shortly after its formation, Helper joined as the program’s co-chair.
Dickerson personally saw the importance of field training. From 1996 to 2002, she worked at NASA’s Johnson Space Center, where part of her job involved co-leading astronaut training field trips with Muehlberger in New Mexico. In collaboration with Muehlberger and astronaut John Young, she initiated instruction in field geophysical methods, including seismic imaging. She recognized that the skill set could prove useful to astronauts who might one day be sent to Mars, a world where much of the bedrock geology is obscured by layers of shifting sand.
Today, Dickerson frequently teaches general audiences about geology on tours organized by the Smithsonian Institution. She said that she was reminded of the synergy between the Jackson School and the Apollo program when, on the week of the 50th anniversary of the first moon landing, she was able to tell a tour group that the Icelandic lava flows that they were visiting had counterparts on the moon, and that her information had come from quite a reliable source: Jack Schmitt, an astronaut who had trained on the very lava flows they were visiting and who had walked among the lunar flows.
Helper, in turn, is lead field geology instructor for NASA’s astronaut candidate program. Beginning with the 2009 astronaut class and continuing to the most recent class selected in 2017, he has designed and taught five-day field exercises involving geologic mapping and field data collection in northern and central New Mexico. He has also taken NASA engineers and scientists, particularly those involved in planning or directing lunar or Martian surface science, on similar trips so they can learn about the nature of geologic field work by doing it for themselves. In addition to wearing these field training hats, Helper has played the role of an astronaut on a simulated Mars geology mission as part of NASA’s Haughton Mars Project, a program that conducted mock Mars mission exercises on an impact crater in Canada’s remote and isolated Devon Island, an analog site for the Red Planet.
Helper said that his experience teaching astronauts has carried over into teaching Jackson School undergraduates in the field. For instance, he tasked students in the 2019 GEO 660 field geology course with the same Rio Grande Gorge field mapping exercise as the 2017 astronaut class. If that sounds intimidating, Helper said that the students did not know they were following in the footsteps of astronauts until later on in the field camp when teaching assistants let it leak. But Helper noted that it’s the astronauts who had it easier; the students having to create more detailed maps in less time.