On July 20, as we mark 45 years since the United States landed men on the Moon, a lot of attention rightly will be focused on the definitive space mission of our era – the voyage of Apollo 11. I will also recall another, more personally defining lunar voyage that flew 43 years ago this month – Apollo 15, one of the most productive, exciting scientific expeditions of the 20th century. Leaving Earth for the Moon on July 26, 1971, this mission gave us a new template for the human exploration of planetary surfaces. As the fourth lunar landing, Apollo 15 is often overlooked in the blur of the latter Apollo missions and today it is primarily remembered as the debut of the Lunar Roving Vehicle – the “dune buggy” that transported our astronauts around the Moon’s surface.
Apollo 15 was the first of the extended Apollo “J missions.” It carried more fuel, more life support capability and a rover, as well as a variety of scientific equipment. These advanced missions, with an emphasis on science, were sent to complex, difficult-to-reach landing sites, usually deep in the highlands or within narrow valleys between gigantic mountains. The advanced capabilities in the lander were complemented by an augmented set of experiments in the orbiting Command Service Module, including a high-resolution panoramic camera, a precision mapping camera, and sensors to measure lunar surface chemistry.
Astronauts for these latter missions underwent intensive training in a variety of scientific disciplines, most notably geology. Graduates of the U.S. Air Force and test pilots, the Apollo 15 crew readily absorbed the equivalent of a Masters degree in geology during their several months of intense training – hard work and dedication that showed in their performance on the Moon. David R. Scott (Commander), James B. Irwin (LM Pilot) and Alfred M. Worden (CM Pilot) were scheduled to land at a geologically complex site nestled at the base of the lunar Apennine Mountains – the rim crest of the enormous Imbrium impact basin, one of the largest and youngest basins on the Moon.
Hadley-Apennine was a mare-highland site – named for both Mt. Hadley (a prominent peak within the Apennine mountains) and Rima Hadley (a canyon-like winding ditch known as a sinuous rille). With an enormous rampart of mountains towering several kilometers over the surrounding mare plain, this site is one of the most beautiful on the Moon. Geologic sampling of both the highlands material of the Apennine Mountains and the mare lavas of the landing site plain was the principal scientific goal of the mission. Investigation of the origin of sinuous Rima Hadley was another, although few thought that all its mysteries would be easily uncovered by a short, strictly choreographed visit.
For me, this mission is the nexus of a variety of professional connections and people with whom I’ve associated over the years. Hadley Rille was postulated to have formed as a lava channel or tube; Ron Greeley (who later became my doctoral dissertation supervisor) published this model in early 1971. One of the geologists training the Apollo 15 crew was Jim Head, later of Brown University and academic advisor for my Master’s degree. The Principal Investigator of the geology team was Gordon Swann, who later became a close friend when I worked for the U.S. Geological Survey in Flagstaff. I met my friend and colleague Graham Ryder through our mutual interest in the problems of Apollo 15 geology and we formed a productive research association that continued for over 20 years. But the most important connection for me was the one I made in spirit with the crew of Apollo 15.
Forty-three years ago, I was an engineering student pursuing studies in electronics with the aim of somehow getting into the space program, but on what terms and how were as yet unclear to me. Then, watching the Apollo 15 crew on the Moon that long-ago July, I was captivated with the idea of conducting geology on the Moon. Up until this mission, geology held little interest for me; I’d collected rocks as a kid and knew some general facts of the science but now, watching and listening to Dave Scott and Jim Irwin working on the Moon, an interest was awakened and with it an excitement for new possibilities that I’d never considered. Imagine – geology, the study of rocks and minerals, applied to the Moon! As strange as it may seem now, that geologic connection was not obvious to me (or to very many others) in those days.
Besides displaying competence as field geologists, the Apollo 15 crew also conveyed excitement in what they were doing. The sheer exuberance of the crew – rolling rocks down the wall of Hadley Rille, finding emerald green glass in soil on the Apennine Front, discovering a piece of pure anorthosite perched like a gem on a pedestal – was enlightening and inspiring. This was not only exciting and fun – it was interesting. I resolved to learn more, but readable books on the subject were almost non-existent. Then I came across an exception – Thomas A. Mutch’s book The Geology of the Moon: A Stratigraphic Approach. I simply devoured this book, a literate and comprehensible work, even to one barely versed in the geological sciences. Tim Mutch was a geologist on the faculty at Brown University, where I later applied for graduate school. Tim was also the PI on the imaging system for the Mars Viking lander, and partly through his good graces, I was accepted as an intern for that mission in the summer of 1976.
These myriad connections (and many more that followed) led to my current career as a planetary scientist, along with the many wonderful opportunities that I have had in this arena. Perhaps it was inevitable, but 40 years later, I find the totality of these connections and coincidences to be truly remarkable. A career path completely changed by the three-day performance of an Apollo crew – test pilots who became (for me), the beau ideal of scientists exploring an alien world.
These threads converged again several years after the Apollo 15 mission when Graham Ryder (Lunar and Planetary Institute in Houston) and I (USGS, Flagstaff) convened a workshop on the geology of the Hadley-Apennine landing site. In attendance were over 60 active lunar scientists, included Ron Greeley, Jim Head, Gordon Swann – and Dave Scott and Jim Irwin. I had spent several days the previous summer with Gordon, Graham and Dave in Flagstaff, watching the videotapes of his moonwalk and re-living those three great days. The most memorable aspect of this workshop was the opportunity to meet my intellectual heroes and tell them how they’d changed my life. So, this month, while most are celebrating the anniversary of the first landing on the Moon, I will be thinking back to another July, one that steered me into a career in planetary science. Admittedly, mine is only one story, but from talking with many colleagues, I’ve found that my experience is not singular.
Recently, the societal value of human spaceflight has become an important subject of debate and contemplation. The recently released National Research Council report on human spaceflight specifically highlighted human spaceflight’s undeniable ability to inspire students – how it can touch them personally and propel them intellectually and academically toward productive careers. Can one truly quantify the value of inspiration – that power and influence that ignites passion in others? I can, as it came to me 43 years ago while watching the Apollo crew doing inspiring things on the Moon. Eric Berger has highlighted this mission (and its enduring implications) in the latest installment of his series on the American civil space program, Adrift.
In a press conference after the mission, Apollo 15 Commander Dave Scott quoted Plutarch as saying, “The mind is not a vessel to be filled, but a fire to be lighted.” That quotation nicely summarizes both the Apollo 15 mission and how it has affected my life.