50 years after historic Moon mission, Brown geologist shares stories from Mission Control

Jim Head, a planetary geologist at Brown, worked closely with the Apollo 15 astronauts on “the first true scientific expedition to the Moon” in 1971.

PROVIDENCE, R.I. [Brown University] — At first, Apollo 15 astronauts Dave Scott and Jim Irwin didn’t quite believe what they were seeing. During an excursion in their lunar rover — the first such vehicle deployed to the Moon — the astronauts spied flecks of green breaking the grayish white monotony of the lunar surface.

“[Are you] sure it’s green and not just white albedo again?” Irwin asked, referring to the tricks sunlight can play on the lunar surface.

“No, it’s green,” Scott confirmed.

Knowing they had something interesting, Scott and Irwin quickly added a few samples to their collection, which returned to Earth along with the Apollo 15 crew 50 years ago.

Image of Dave Scott and Jim Head at Brown
Dave Scott (left) and Jim Head (right) look at samples from the Apollo 15 mission in Brown's Lincoln Field Building

More than 35 years later, those green flecks, which turned out to be beads of volcanic glass, found their way to a lab at Brown, where geologist Alberto Saal showed that they contained surprising amounts of water. It was the first unequivocal evidence that the Moon’s interior, long thought to have been stripped of any water during its formation, wasn’t so dry after all.

“That has absolutely revolutionized our thinking about how the Moon formed and how solar system bodies interact,” said Jim Head, a professor of geological sciences at Brown who worked on the Apollo program and was inside NASA’s Mission Control Center as Scott and Irwin explored the Moon. “That was a tremendously important discovery that Dave and Jim made on that mission.”

It was one discovery among many for what Head said was one of the most productive scientific missions in the history of spaceflight.

“Everybody knows about the historic Apollo 11, but most people aren’t very aware of the subsequent missions,” Head said. “Apollo 15 was the first true scientific expedition to the Moon, and it was incredibly successful.”

Apollo 15 was the first of what NASA termed J-type missions — missions with vastly expanded scientific capabilities. Apollo 11, the first lunar landing, demonstrated that a safe landing on the Moon was indeed possible. The next two landings, Apollo 12 and 14, achieved pinpoint touchdowns on rough terrain. Those technical feats set the stage for the tricky Apollo 15 landing in an area of high scientific interest: a spot situated between the towering Apennine Mountains and Hadley Rille, a deep channel carved by ancient lunar lava flows.  

Head, an expert in lunar and planetary geology whose first job after earning his Ph.D. from Brown was on the Apollo program, played a key role in choosing that landing site.

Everybody knows about the historic Apollo 11, but most people aren’t very aware of the subsequent missions. Apollo 15 was the first true scientific expedition to the Moon, and it was incredibly successful.

Jim Head Professor of geological sciences
Image of Jim Head

Head wrote a memo to NASA managers identifying five areas of scientific interest along Hadley Rille. One of those, which turned out to be the eventual landing site, was particularly interesting from a scientific perspective, but would also require a landing angle far steeper than any that had been attempted previously. Scott, who was mission commander, agreed that the mission should attempt to land where the best science could be done.

“So Dave jumps in the simulator to try this steep landing,” Head recalled. “He tries it; says we’re good to go, and that’s where we ended up going.”

Once on the surface, the real scientific work began. Scott and Irwin would perform over 19 hours of extravehicular activities (EVAs), twice the EVA time logged on previous missions. The solar-powered Lunar Roving Vehicle, a remarkable feat of engineering in its own right, enabled the astronauts to traverse a previously unthinkable 17 miles across the lunar surface. The mission returned to Earth with 170 pounds of lunar material. Apollo 11, by contrast, brought home a little over 47 pounds.

Head was among the scientists whose job it was to teach two test pilots how to do geology on another world. Head said that Scott in particular was a natural geologist and became engrossed in the subject.   

“One of the best compliments I ever had,” Head said, “was from Dave’s wife at the time, who took me aside and said, ‘Jim, you've absolutely ruined Dave. I had to take a night school course in geology just to be able to talk to him at dinner.’”

The training paid big dividends. In addition to the green volcanic glass, Scott and Irwin gathered one of the big stars in NASA’s lunar sample collection, known as the “genesis rock.” One of the reasons Head and other scientists wanted to land in the lunar highlands was the potential for finding samples of the original deep lunar crust. When Scott spotted the ancient chunk an anorthosite sitting on the surface, he recognized it instantly, enthusiastically radioing to mission control: “Guess what we just found! I think we found what we came for.”

Later in the mission, another important specimen caught Scott’s eye: a basalt that was full of holes, or vesicles, left behind by gas escaping from rising lava. EVA time was quickly drawing to a close and mission managers were ever wary of staying out too long. But Scott knew he had to have that rock: He and Head had discussed the importance of vesicular basalts in understanding what gases were present in the lunar interior. Rather than ask for a time extension, Scott simply jumped off the rover and grabbed the rock, while telling Mission Control that he needed to adjust his seatbelt — an action Scott described as “the commander’s prerogative.” The sample would come to be known in the scientific community as the “seatbelt basalt,” another star of NASA’s collection. 

Image of Hadley Rille on the Moon
Hadley Rille, near the Apollo 15 landing site, was carved by an ancient lava flow.

Head and his fellow Apollo scientists were in mission control in Houston during the mission and were able to communicate with the crew. But they weren’t there to micromanage, only to provide expertise when needed.

 “The astronauts did this work on their own,” Head said. “It wasn’t like we were saying, ‘send us a picture of the rock and we’ll tell you if it’s good.’ The mantra was, ‘train them, trust them and turn them loose.’”

Head described the science room in the Mission Operations Center as an incredibly intense and busy place — so busy, in fact, that Head missed it when Scott dropped Head’s name in communications with Mission Control, referring to the valley containing Hadley Rille as “Head Valley.”

“Dave said something like, ‘I’m looking down Head Valley,’ and someone poked me and said, ‘Hey, did you hear that?’” Head recalls. “I was planning the next traverse; I completely missed it. But Dave did that for several of the scientists who worked closely with him and it was really thoughtful.”

Head and Scott remain close friends and collaborators to this day. Scott has worked with Brown students over the years as a visiting professor, and the University awarded him an honorary degree in 2011.  Most recently, on July 31, 2021, Head joined Scott at an event at the San Diego Air and Space Museum to commemorate the mission’s 50th anniversary.

The pair have worked with researchers at the Massachusetts Institute of Technology and elsewhere to show how Apollo 15 could serve as a template for future missions to the Moon and Mars. They refer to the close collaboration between scientists and engineers — the work they say made Apollo 15 possible — as “science-engineering synergism.”

“The geologists and scientists worked together with engineers and managers to optimize the program,” Scott said during a 2013 visit to Brown. “It’s the kind of thing Jim and I are trying to emphasize ... so that the science community understands the engineering and the engineers understand the science. Working together, we get better science and better engineering.”

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