Apollo 15

• 1. Introduction

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  Apollo 15 launched on the 26th of July 1971, and from the moment it left the ground, it was a different kind of Moon mission. The crew carried redesigned space suits with a new waist joint that let them actually bend and sit. Their lunar lander was heavier than any before it. And waiting for them on the surface was something no human had ever driven on another world: a four-wheeled rover built by Boeing for $40 million.

  Commander David Scott had pushed hard for a science-first approach. He had spent 20 months in geology field trips across Arizona and New Mexico, learning how to read a landscape and describe it to people who could not see it. When NASA redesignated the mission as the first of its extended J missions, Scott did not just accept the new scope. He set about making the most of every hour the expanded stay time allowed.

  What followed was 12 days, 7 hours, 11 minutes and 53 seconds of spaceflight that produced the Genesis Rock, the first deep-space spacewalk in history, a hammer-and-feather experiment watched by millions, and a postal cover scandal that ended three careers. Apollo 15 also left behind a secret: a small aluminum figurine on the lunar surface, and a controversy over who made it that would not fully surface for decades.

• 2. A Different Crew

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  David Scott was born in 1932 in San Antonio, Texas. He had transferred from the University of Michigan, where he held a swimming scholarship, to the United States Military Academy, graduating in 1954. By the time NASA selected him in 1963 as part of its third astronaut group, he had already earned two advanced degrees from MIT. He had flown in Gemini 8 alongside Neil Armstrong in 1966 and served as command module pilot of Apollo 9 in 1969.

  Alfred Worden was also born in 1932, in Jackson, Michigan, and he too had attended West Point, graduating in 1955. He later earned two master's degrees in engineering from the University of Michigan in 1963. James Irwin had been born in 1930 in Pittsburgh and attended the United States Naval Academy, graduating in 1951, before earning a master's degree from Michigan in 1957. Worden and Irwin were both selected in the fifth astronaut group in 1966, and Apollo 15 would be the only spaceflight for each of them. All three men had attended Michigan at some point; the school had been the first university in the country to offer an aeronautical engineering program.

  Geologist Harrison Schmitt had pushed for more science on the early Apollo missions and was often rebuffed. He eventually connected Scott's crew with Caltech geologist Lee Silver, who became their primary geology teacher. Silver's training with the Apollo 13 crew had gone largely to waste after the explosion that forced that mission to abort. With Apollo 15, the approach found a crew genuinely eager to use it. Scott described himself as a serious amateur who came to enjoy field geology, and in Silver he found a teacher whose standards matched his own ambitions.

  The training strained personal lives. Both Worden and Irwin feared that marital difficulties might cost them their seats, and each went to Scott for advice. Scott consulted Deke Slayton, the Director of Flight Crew Operations, who replied that what mattered was whether the astronauts could do their jobs. The Irwins resolved their difficulties before launch. Worden and his wife divorced before the mission flew.

• 3. Machines for the Moon

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  The command module for Apollo 15 was CSM-112, call sign Endeavour, named after HMS Endeavour. Scott's stated reason was that Endeavour's captain, James Cook, had commanded the first purely scientific sea voyage. Apollo 15 carried a small piece of wood from Cook's ship. The lunar module, LM-10, was call sign Falcon, named after the mascot of the United States Air Force Academy, and it carried two falcon feathers to the Moon to honor the crew's Air Force service.

  The upgraded space suits, designated A7LB, moved the life-support connectors into triangular pairs instead of two parallel rows, and relocated the entry zipper to run diagonally from the right shoulder to the left hip. These changes allowed the crew to bend completely at the waist and sit in the rover's seats, neither of which had been possible before. Upgraded backpacks extended the time astronauts could spend outside.

  NASA had been thinking about a surface vehicle since the early 1960s. An early concept called MOLAB had a closed cabin and would have massed roughly 6,000 lb. As it became clear no permanent base was coming, something much lighter was needed instead. Boeing received contracts for three rovers, each to be kept under about 500 lb. Cost overruns, particularly in the navigation system, pushed the total to $40 million for all three vehicles, drawing significant press attention at a time when NASA's budget was under pressure.

  The finished Lunar Roving Vehicle folded into a space 5 ft by 20 in and weighed 460 lb unloaded. Carrying two astronauts and gear, it reached 1,500 lb. Each wheel ran off an independent quarter-horsepower electric motor, and the vehicle could travel at up to 6 to 8 mph on the surface. A plaque on Apollo 15's rover read: "Man's First Wheels on the Moon, Delivered by Falcon, the 30th of July 1971".

  The Saturn V for the mission, designated SA-510, launched in a more southerly direction than earlier flights and flew to a lower Earth parking orbit of 166 km. Together, those changes allowed the rocket to carry 1,100 lb more payload than it otherwise could have. The number of retrorockets on the first stage was cut from eight to four, and the propellant reserves were trimmed accordingly.

• 4. Getting There

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  Apollo 15 lifted off on the 26th of July 1971 at 9:34 am Eastern time from Launch Complex 39A at the Kennedy Space Center at Merritt Island, Florida. The launch window was just two hours and 37 minutes. Had the mission slipped past a second window on July 27, the next opportunity would not have come until late August.

  During the journey out, a warning light in the service propulsion system triggered considerable troubleshooting. The crew avoided using the affected control bank for all but critical burns and flew the system manually when necessary. After the mission, the malfunction traced to a tiny piece of wire caught inside a switch.

  A water leak appeared around 61 hours into the flight on the evening of July 28 in Houston. Scott could not find the source, and the crew mopped it up with towels, which were then hung to dry in the tunnel between the command module and the Lunar Module. Scott later said it looked like someone's laundry. Engineers in Houston devised a fix that the crew carried out successfully.

  Approaching lunar orbit insertion, the burn had to take place on the far side of the Moon, out of contact with Earth. Mission Control used the timing of the signal resumption to confirm the burn had occurred. When Scott's voice returned, he spoke admiringly about the Moon's beauty rather than immediately reporting burn details. Alan Shepard, the Apollo 14 commander, who was waiting nearby for a television interview, cut in: "To hell with that shit, give us details of the burn." The 398.36-second burn took place at 78 hours, 31 minutes and 46.7 seconds into the mission, at an altitude of 86.7 nautical miles above the Moon, placing Apollo 15 in an elliptical lunar orbit of 170.1 by 57.7 nautical miles.

• 5. Hadley Rille

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  Scott had insisted on Hadley Rille as the landing site partly because of what it looked like. When the Site Selection Committee narrowed the choices to Hadley or the crater Marius, Scott said of Hadley: "There is a certain intangible quality which drives the spirit of exploration and I felt that Hadley had it. Besides it looked beautiful and usually when things look good they are good." NASA lacked high-resolution images of the site, as it had been considered too rough for earlier missions. The approach trajectory required a descent angle of 26 degrees, far steeper than the 15 degrees used on previous landings.

  Falcon touched down on July 30. During final approach, Scott could not immediately recognize the terrain he had practiced in simulation. A navigation error of about 3,000 ft placed them slightly off the planned path, and the craters he had used as visual markers in training were hard to identify under real lunar lighting. Below about 60 ft, the engine exhaust raised so much dust that Scott could see nothing of the surface. When Irwin called "Contact" as a landing probe touched the ground, Scott shut the engine off immediately rather than risk blowback from the engine exhaust reflecting off the surface. Falcon fell the last 1.6 ft and landed at roughly 6.8 ft per second, the hardest lunar touchdown of any crewed mission. The lander settled back at an angle of 6.9 degrees and tilted to the left 8.6 degrees. Irwin wrote later that it was the hardest landing he had ever experienced, and he feared for a moment the craft would keep tipping.

  Scott reported: "Okay, Houston. The Falcon is on the Plain at Hadley." About 103 seconds of fuel remained, and the lander sat roughly 1,800 ft from the planned landing site.

  Before the first full Moon walk, Scott opened the lander's top docking hatch and spent half an hour surveying the site from an elevated position, becoming the only astronaut to conduct a stand-up extravehicular activity through the Lunar Module's top hatch while on the surface. Lee Silver had taught him to survey from high ground before any fieldwork. Slayton and other managers had initially opposed it because of the oxygen that would be vented, but Scott prevailed. After repressurizing the cabin, Scott and Irwin removed their suits to sleep, the first time astronauts had done so while on the Moon.

• 6. Science on the Surface

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  Scott and Irwin became the seventh and eighth humans to walk on the Moon when they began their first full EVA together. Deploying the rover from Falcon's descent stage proved awkward because of the lander's tilt. Once the rover was free and Scott began his system checkout, the front-wheel steering failed. Rear-wheel steering alone was enough. Rolling away from the lander, Scott said "Okay. Out of detent; we're moving" mid-sentence, making those the first words spoken by a human while driving on another world.

  The centerpiece of the second EVA, on August 1, was time spent on the slope of Mons Hadley Delta. At Spur crater, Scott and Irwin found a pale crystalline rock. The sample, later called the Genesis Rock, is an anorthosite believed to be part of the early lunar crust. The hope of finding just such a specimen had been part of the scientific justification for choosing the Hadley site.

  During the third EVA, a core sample consumed far more time than planned. The crew struggled to pull it free from the surface and then to break it into transportable lengths. A vise mounted on the rover proved incorrectly positioned for the job. Scott wondered aloud whether the effort had been worth it. CAPCOM Joe Allen assured him it was, and the core later turned out to be among the most scientifically valuable samples returned from the Moon, revealing significant detail about the history of the lunar interior.

  At the end of the surface work, Scott dropped a falcon feather and a hammer simultaneously in front of the television camera. Because the Moon's atmosphere is negligible, both hit the ground at the same moment. The experiment demonstrated Galileo's principle that in the absence of air resistance, all objects fall at the same rate regardless of mass. The idea had come from Allen. The feather was most likely from a female gyrfalcon, the mascot species at the United States Air Force Academy.

  Before leaving the rover for the last time, Scott placed a small aluminum figurine called Fallen Astronaut near it, along with a plaque listing 14 American astronauts and Soviet cosmonauts who had died in the pursuit of space exploration. He turned the television camera away while doing so and told Mission Control he was doing cleanup work around the rover. He disclosed the memorial at a post-flight press conference. He also left a Bible on the rover's control panel.

• 7. Worden in Orbit

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  Alfred Worden orbited the Moon alone for most of the time Scott and Irwin were on the surface. He operated six scientific instruments housed in the service module's scientific instrument module bay: a panoramic camera derived from aerial-reconnaissance technology, a metric camera, a gamma-ray spectrometer, an X-ray spectrometer, a laser altimeter, and a mass spectrometer. The altimeter failed partway through the mission. A boom for the mass spectrometer repeatedly failed to fully retract.

  Worden had spent much of his training time at North American Rockwell's facilities in Downey, California, learning from geologist Farouk El-Baz how to describe lunar terrain in ways useful to scientists who would listen to the recordings. He often flew over the geology field trips rather than attending on the ground, practicing descriptions from altitude at the speed the lunar landscape would pass below the command module. El-Baz also helped Worden accumulate translations for a personal tradition: after each passage through the Moon's shadow cut communication with Earth, Worden greeted the return of contact with the words "Hello, Earth. Greetings from Endeavour," each time in a different language.

  Data from the X-ray spectrometer showed greater fluorescent X-ray flux than expected and indicated the lunar highlands were richer in aluminum than the mares. Worden's photographs and descriptions from orbit, taken from a more inclined path than earlier crewed missions, revealed surface features not previously documented. His observations would contribute to the decision to send Apollo 17 to Taurus-Littrow to look for signs of past volcanic activity.

  On August 5, during the return to Earth, Worden conducted a 39-minute EVA to retrieve film cassettes from the SIM bay, with Irwin stationed at the command module hatch. At approximately 171,000 nautical miles from Earth, it was the first spacewalk performed in deep space. As of the date the source was written, it remained one of only three such EVAs, all carried out during Apollo J missions.

• 8. Controversies and Consequences

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  The Apollo 15 crew had agreed before the flight to carry roughly 400 postal covers to the Moon in exchange for about $7,000 each, money they intended for their children's futures. Walter Eiermann, who had extensive professional ties to NASA and the astronaut corps, acted as intermediary between the crew and West German stamp dealer Hermann Sieger. Scott carried the covers aboard and they were transferred into Falcon for the surface operations. No approval had been obtained from Slayton, as NASA rules required.

  After the mission, 100 covers were handed to Eiermann, who passed them to Sieger for sale to customers at roughly $1,500 per cover in late 1971. When the payments arrived, the astronauts returned them and declined the money. In April 1972, Slayton found out, and removed the three from the backup crew for Apollo 17. The matter became public in June 1972. All three astronauts were reprimanded for poor judgment, and none flew in space again. Covers still in their possession at the time of the investigation were surrendered; after Worden filed suit, those covers were returned in 1983.

  A separate dispute arose over Fallen Astronaut. Before the mission, Scott had made a verbal agreement with Belgian artist Paul Van Hoeydonck to create the statuette. Scott's intention was a simple, anonymous memorial with no commercial dimensions, apart from a single copy for public display at the National Air and Space Museum. Van Hoeydonck understood the arrangement differently, believing he would receive public recognition and rights to sell replicas. Under NASA pressure, Van Hoeydonck canceled a plan to sell 950 signed copies. In 2021, Scott published a document titled "Memorandum for the Record" stating the figurine had actually been made by NASA personnel, a claim that contradicted his 1972 testimony before a Senate committee that Van Hoeydonck had made it at Scott's request.

  Also examined during those congressional hearings was Scott's use on the lunar surface of a Bulova watch. NASA had selected Omega as the program's standard timepiece, but Scott had been introduced to Bulova's representative by Apollo 8 commander Frank Borman before the mission and brought the watch without disclosing it to Slayton. The crystal on his Omega Speedmaster popped off during his second EVA, and he wore the Bulova prototype during the third. In 2015, that Bulova Chronograph Model #88510/01 sold at auction for $1.625 million.