Apollo 15 & the Lunar Rover

United States #1435 (1971)
United States #1435 (1971)

On July 30, 1971, Apollo 15 landed on the Moon with the first Lunar Roving Vehicle. This was the ninth manned mission in the United States’ Apollo program, the fourth to land on the Moon, and the eighth successful manned mission. It was the first of what were termed “J missions”, long stays on the Moon, with a greater focus on science than had been possible on previous missions. The mission began on July 26, 1971, and ended on August 7. At the time, NASA called it the most successful manned flight ever achieved.

Commander David Scott and Lunar Module Pilot James Irwin spent three days on the Moon, including 18½ hours outside the spacecraft on lunar extra-vehicular activity (EVA). The mission landed near Hadley rille, in an area of the Mare Imbrium called Palus Putredinus (Marsh of Decay). The crew explored the area using the first lunar rover, which allowed them to travel much farther from the Lunar Module (LM) than had been possible on missions without the rover. They collected 170 pounds (77 kilograms) of lunar surface material. At the same time, Command Module Pilot Alfred Worden orbited the Moon, using a Scientific Instrument Module (SIM) in the Service Module (SM) to study the lunar surface and environment in great detail with a panoramic camera, a gamma-ray spectrometer, a mapping camera, a laser altimeter, a mass spectrometer, and a lunar sub-satellite deployed at the end of Apollo 15’s stay in lunar orbit (an Apollo program first).

The mission successfully accomplished its objectives, but was marred by negative publicity that accompanied disclosure of the crew carrying unauthorized postage stamps which they had planned to sell after their return. Ironically, this mission was one of very few that had been honored with the issue of a commemorative U.S. stamp, with this first use of a lunar rover happening one decade after the first Mercury astronaut launch.

The crew for Apollo 15 consisted of Commander David R. Scott on his third and last spaceflight, Command Module Pilot Alfred M. Worden, and Lunar Module Pilot James B. Irwin both on their only trip to space. All three astronauts on the all-United States Air Force crew received an honorary degree or master’s degree from the University of Michigan, including Scott’s honorary degree, awarded in the spring of 1971, months before the launch. Scott had attended the University of Michigan, but left before graduating to accept an appointment to the United States Military Academy. The crewmen did their undergraduate work at either the United States Military Academy or the United States Naval Academy. They had previously served as the backup crew for Apollo 12. There had been a friendly rivalry between that prime and backup crew on that mission, with the prime being all United States Navy, and the backup all United States Air Force.

Originally Apollo 15 would have been an H mission, like Apollos 12, 13 and 14. But on September 2, 1970, NASA announced it was canceling what were to be the current incarnations of the Apollo 15 and Apollo 19 missions. To maximize the return from the remaining missions, Apollo 15 would now fly as a J mission and have the honor of carrying the first lunar rover.

One of the major changes in the training for Apollo 15 was the geology training. Although on previous flights the crews had been trained in field geology, for the first time Apollo 15 would make it a high priority. Scott and Irwin would train with Leon Silver, a Caltech geologist who on Earth was interested in the Precambrian. Silver had been suggested by Harrison Schmitt as an alternative to the classroom lecturers that NASA had previously used. Among other things, Silver had made important refinements to the methods for dating rocks using the decay of uranium into lead in the late 1950s.

At first, Silver would take the prime and backup crews to various geological sites in Arizona and New Mexico as if for a normal field geology lesson, but as launch time approached, these trips became more realistic. Crews began to wear mock-ups of the backpacks they would carry, and communicate using walkie-talkies to a CAPCOM in a tent. During a mission the Capsule Communicators (CAPCOMs), always fellow astronauts, were the only people who normally would speak to the crew. The CAPCOM was accompanied by a group of geologists unfamiliar with the area who would rely on the astronauts’ descriptions to interpret the findings.

The decision to land at Hadley came in September 1970. The Site Selection Committees had narrowed the field down to two sites — Hadley Rille or the crater Marius, near which were a group of low, possibly volcanic, domes. Although not ultimately his decision, the commander of a mission always held great sway. To David Scott the choice was clear, with Hadley, being “exploration at its finest.”

Command Module Pilot Alfred Worden undertook a different kind of geology training. Working with an Egyptian-born geologist, Farouk El-Baz, he flew over areas in an airplane simulating the speed at which terrain would pass below him while in the Apollo Command/Service Module (CSM) in orbit. He became quite adept at making geologic observations as objects passed below.

Technicians at the Kennedy Space Center had many problems with the SIM bay in the Service Module. It was the first time it had flown and experienced problems from the start. Problems came from the fact the instruments were designed to operate in zero gravity, but had to be tested in the 1 g on the surface of the Earth. As such, things like the 7.5 m booms for the mass and gamma ray spectrometers could only be tested using railings that tried to mimic the space environment, and so they never worked particularly well. When the technicians tried to integrate the entire bay into the rest of the spacecraft, data streams would not synchronize, and lead investigators of the instruments would want to make last minute checks and changes. When it came time to test the operation of the gamma-ray spectrometer, it was necessary to stop every engine within 10 miles (16 km) of the test site.

On the Lunar Module, the fuel and oxidizer tanks were enlarged on both the descent and ascent stages and the engine bell on the descent stage was extended. Batteries and solar cells were added for increased electrical power. In all this increased the weight of the Lunar Module to 36,000 pounds (16,000 kilograms), 4,000 pounds (1,800 kg) heavier than previous models.

Left to right: David R. Scott, Alfred M. Worden, James B. Irwin

The three astronauts of Apollo 15 were all United States Air Force active duty officers, and their patch carries Air Force motifs (just as the Apollo 12 all-Navy crew’s patch had featured a sailing ship). The circular patch features stylized red, white and blue birds flying over the Hadley Rille section of the Moon. Immediately behind the birds, a line of craters form the Roman numeral XV. The artwork is circled in red, with a white band giving the mission and crew names and a blue border. Scott contacted fashion designer Emilio Pucci to design the patch, who came up with the basic idea of the three-bird motif on a square patch. The crew changed the shape to round and the colors from blues and greens to a patriotic red, white and blue. Worden stated that each bird also represented an astronaut, white being his own color (and as Command Module Pilot, uppermost), with Scott the blue bird and Irwin the red. The Roman numeral design was created when NASA insisted that the mission number be displayed in Arabic numerals.

Apollo 15 used Command/Service Module CSM-112, which was given the call sign Endeavour, named after the HMS Endeavour and Lunar Module LM-10, call sign Falcon, named after the United States Air Force Academy mascot. If Apollo 15 had flown as an H mission, it would have been with CSM-111 and LM-9. That CSM was used by the Apollo–Soyuz Test Project in 1975, but the Lunar Module went unused and is now on display at the Kennedy Space Center Visitor Complex.

Apollo 15 was launched on July 26, 1971, at 9:34 AM EDT from the Kennedy Space Center at Merritt Island, Florida. During the launch, the S-IC did not completely shut off following staging for four seconds, creating the possibility of the spent stage banging into the S-II engines, damaging them and forcing an abort (the S-II exhaust also struck a telemetry package on the S-IC and caused it to fail). Despite this, the third stage and spacecraft reached its planned Earth parking orbit. A couple of hours into the mission, the third stage reignited to propel the spacecraft out of Earth orbit and on to the Moon.

A few days after launching from Florida, the spacecraft passed behind the far side of the Moon, where the Service Propulsion System (SPS) engine on the CSM ignited for a six-minute burn, to slow the craft down into an initial lunar orbit. Once the lowest point of altitude in the orbit was reached, the SPS engine was fired again, to place the spacecraft into the proper descent orbit for the Lunar Module landing at Hadley.

Most of the first part of the day after arriving in lunar orbit on July 30 was spent in preparing the Lunar Module for descent to the lunar surface later on that day. When preparations were complete, undocking from the CSM was attempted; it did not occur, because of a faulty seal in the hatch mechanism. The Command Module Pilot, Alfred Worden, resealed the hatch; the LM then separated from the CSM. David Scott and James Irwin continued preparations for the descent while Worden remained in the CSM, returning to a higher orbit to perform lunar observations and await his crewmates’ return a few days later.

Soon, Scott and Irwin began the descent to the Hadley landing site. Several minutes after descent was initiated, at pitch-over and the beginning of the approach phase of the landing, the LM was six kilometers east of the previously selected landing target. On learning this, Scott altered the flight path of the LM. They touched down at 22:16:29 UTC on July 30 at Hadley, within a few hundred meters of the planned landing site. One of the legs of the LM landed in a small crater so the module was tilted by 10° — the maximum acceptable was 15°. While previous crews had exited the Lunar Module shortly after landing, the crew of Apollo 15 elected to spend the rest of the day inside the LM, waiting until the next day to perform the first of three EVAs, or moonwalks, in order to preserve their sleep rhythm on a mission on which they were to spend a significantly longer time on the surface than previous crews had spent. Before they slept, Scott performed a stand-up EVA, during which the LM was depressurized and he photographed their surroundings from the top docking hatch.

Throughout the sleep period, Mission Control, in Houston, monitored a slow but steady oxygen leak. The data output of the onboard telemetry computers was limited during the night to conserve energy, so controllers could not determine the exact cause of the leak without awaking the crew. Scott and Irwin eventually were awakened an hour early, and the source of the leak was found to be an open valve on the urine transfer device. After the problem was solved, the crew began preparation for the first Moon walk.

Four hours later, Scott and Irwin became the seventh and eighth humans, respectively, to walk on the Moon. After unloading the Lunar Roving Vehicle (LRV), the two drove to the first moonwalk’s primary destination, Elbow Crater, along the edge of Hadley Rille. The Lunar Roving Vehicle (LRV) or lunar rover was a battery-powered four-wheeled rover used on the Moon in the last three missions of the American Apollo program (15, 16, and 17) during 1971 and 1972. It was popularly known as “moon buggy”, a play on the words “dune buggy”. The LRV was transported to the Moon on the Apollo Lunar Module (LM) and, once unpacked on the surface, could carry one or two astronauts, their equipment, and lunar samples. The three LRVs remain on the Moon.

One of a series of images taken as a pan of the Apollo 15 landing site, taken by Commander Dave Scott. Featured is the Lunar Roving Vehicle at its final resting place after EVA-3. At the back is a rake used during the mission. Also note the red Bible atop the hand controller in the middle of the vehicle, placed there by Scott. (August 1, 1971)
One of a series of images taken as a pan of the Apollo 15 landing site, taken by Commander Dave Scott. Featured is the Lunar Roving Vehicle at its final resting place after EVA-3. At the back is a rake used during the mission. Also note the red Bible atop the hand controller in the middle of the vehicle, placed there by Scott. (August 1, 1971)

The concept of a lunar rover predated Apollo, with a 1952–1954 series in Collier’s Weekly magazine by Wernher von Braun and others, “Man Will Conquer Space Soon!” In this, von Braun described a six-week stay on the Moon, featuring 10-ton tractor trailers for moving supplies. In 1956, Mieczyslaw G. Bekker published two books on land locomotion. At the time, Bekker was a University of Michigan professor and a consultant to the U.S. Army Tank-Automotive Command’s Land Locomotion Laboratory. The books provided much of the theoretical base for future lunar vehicle development.

In the February 1964 issue of Popular Science, von Braun, then director of NASA’s Marshall Space Flight Center (MSFC), discussed the need for a lunar surface vehicle, and revealed that studies had been underway at MSFC in conjunction with Lockheed, Bendix, Boeing, General Motors, Brown Engineering, Grumman, and Bell Aerospace.

Beginning in the early 1960s, a series of studies centering on lunar mobility were conducted under MSFC. This began with the Lunar Logistics System (LLS), followed by the Mobility Laboratory (MOLAB), then the Lunar Scientific Survey Module (LSSM), and finally the Mobility Test Article (MTA). In early planning for the Apollo program, it had been assumed that two Saturn V launch vehicles would be used for each lunar mission: one for sending the crew aboard a Lunar Surface Module (LSM) to lunar orbit, landing, and returning, and a second for sending an LSM-Truck (LSM-T) with all of the equipment, supplies, and transport vehicle for use by the crew while on the surface. All of the first MSFC studies were based on this dual-launch assumption, allowing a large, heavy, roving vehicle.

The LLS studies were begun by Grumman and Northrop in the fall of 1962; these were designs for pressurized cabin vehicles with electric motors for each wheel. At about this same time, Bendix and Boeing were conducting internal studies on lunar transportation systems. Bekker, now with General Motors Defense Research Laboratories (GMDRL) at Santa Barbara, California, was completing a study for NASA’s Jet Propulsion Laboratory on a small, unmanned lunar roving vehicle for the Surveyor program. Ferenc Pavlics, originally from Hungary, used a wire-mesh design for “resilient wheels,” a design that would be followed in future small rovers.

In early 1963, NASA selected MSFC for studies in an Apollo Logistics Support System (ALSS). Following reviews of all earlier efforts, this resulted in a 10-volume report. Included was the need for a pressurized vehicle in the 6,490–8,470 pound (2,940–3,840 kg) weight range, accommodating two men with their expendables and instruments for traverses up to two weeks in duration. This was called a Mobility Laboratory (MOLAB).[5] In June 1964, MSFC awarded contracts for MOLAB studies and Mobility Test Articles (MTAs) to Bendix and to Boeing, with GMDRL as vehicle technology subcontractor. Bell Aerospace was already under contract for studies of Lunar Flying Vehicles.

Even as ALSS was underway, MSFC was examining a less ambitious surface exploration activity, the Local Scientific Surface Module (LSSM). This would be composed of a fixed, habitable shelter-laboratory (SHELAB) with a small lunar-traversing vehicle (LTV) that could either carry one man or be remotely controlled. LSSM would be carried on an LSM-T, thus still requiring a dual launch. The Propulsion and Vehicle Engineering (P&VE) support contractor Hayes International made a preliminary study of the shelter and vehicle.[7] Also, for the potential need of a MOLAB-like vehicle in future, enlarged lunar explorations, the MOLAB efforts were continued for some time, resulting in several full-scale MTAs.

With pressure from Congress to hold down Apollo costs, Saturn V production was reduced, allowing only a single booster per mission. It would then be necessary for any roving vehicle to be carried on the same Lunar Module as transporting the astronauts. In November 1964, ALSS was put on indefinite hold, but Bendix and Boeing were given study contracts for small rovers under the LSSM program. The name of the Lunar Excursion Module was changed to simply the Lunar Module, indicating that the capability for powered “excursions” away from a lunar-lander base did not yet exist. There could be no SHELAB — the astronauts would work out of the LM — and the LTV accommodating two persons took the name Local Scientific Surface Module (LSSM). MSFC was also examining unmanned robotic rovers that could be controlled from the Earth.

From the start of MSFC, Huntsville, Alabama-based Brown Engineering Company (BECO) had participated in all of its lunar mobility efforts. In 1965, BECO became the prime support contractor for MSFC’s P&VE Laboratory. With an urgent need to determine the feasibility of a two-man LSSM, von Braun bypassed the usual procurement process and had P&VE’s Advanced Studies Office directly task BECO to design, build, and test a MTA for the vehicle. While Bendix and Boeing would continue with work leading to LSSM concepts and designs, the MTA was vital for MSFC human factors studies involving spacesuit-clad astronauts interfacing with power, telemetry, navigation, and life-support equipment on the rover.

In designing the LSSM MTA, full use was made of all earlier small-rover studies, and commercially available components were incorporated wherever possible. The selection of wheels was of great importance, and almost nothing was known at that time about the lunar surface. The MSFC Space Sciences Laboratory (SSL) was responsible for predicting surface properties. BECO was also the prime support contractor for the SSL and set up a test area to examine a wide variety of wheel-surface conditions. To simulate Pavlics’ “resilient wheel,” a four-foot-diameter inner tube wrapped with nylon ski rope was used. On the MTA, each wheel had a small electric motor, with overall power provided by standard truck batteries. A roll bar gave protection from overturn accidents.

In early 1966, BECO’s MTA became available for examining human factors and other testing. MSFC built a small test track with craters and rock debris where the LSSM and MOLAB MTAs were compared; it was soon obvious that a small rover would be best for the proposed missions. The vehicle was also operated in remote mode to determine characteristics in tests that might be dangerous to the operator, such as acceleration, bounce-height, and turn-over tendency as it traveled at higher speeds and over simulated obstacles. The LSSM performance under one-sixth gravity was obtained through flights on a KC-135A aircraft in a Reduced Gravity parabolic maneuver; among other things, the need for a very soft wheel and suspension combination was shown. Although Pavlics’ wire-mesh wheels were not available for the MTA, testing of these was conducted on various soils at the Waterways Experiment Station of the U.S. Army Corps of Engineers at Vicksburg, Mississippi. Later, when wire-mesh wheels were tested on low-g flights, the need for wheel fenders to reduce dust contamination was found. The LSSM MTA was extensively tested at the U.S. Army’s Yuma Proving Ground in Arizona, as well as the Army’s Aberdeen Proving Ground in Maryland.

During 1965 and 1967, the Summer Conference on Lunar Exploration and Science brought together leading scientists to assess NASA’s planning for exploring the Moon and to make recommendations. One of their findings was that the LSSM was critical to a successful program and should be given major attention. At MSFC, von Braun established the Lunar Roving Task team, and in May 1969, NASA selected the Lunar Roving Vehicle (LRV) for use in manned lunar missions and approved the Manned Lunar Rover Vehicle Program as a MSFC hardware development. Saverio F. “Sonny” Morea was named the LRV program manager.

On July 11, 1969, just before the successful Moon landing of Apollo 11, a request for proposal for the final development and building the Apollo LRV was released by MSFC. Boeing, Bendix, Grumman, and Chrysler submitted proposals. Following three months of proposal evaluation and negotiations, Boeing was selected as the Apollo LRV prime contractor on October 28, 1969. Boeing would manage the LRV project under Henry Kudish in Huntsville, Alabama. As a major subcontractor, General Motors’ Defense Research Laboratories in Santa Barbara, California, would furnish the mobility system (wheels, motors, and suspension); this effort would be led by Ferenc Pavlics. Boeing in Seattle, Washington, would furnish the electronics and navigation system. Vehicle testing would take place at the Boeing facility in Kent, Washington, and the chassis manufacturing and overall assembly would be at the Boeing facility in Huntsville.

The first cost-plus-incentive-fee contract to Boeing was for $19,000,000 and called for delivery of the first LRV by April 1, 1971. Cost overruns, however, led to a final cost of $38,000,000, which was about the same as NASA’s original estimate. Four lunar rovers were built, one each for Apollo missions 15, 16, and 17; and one used for spare parts after the cancellation of further Apollo missions. Other LRV models were built: a static model to assist with human factors design; an engineering model to design and integrate the subsystems; two one-sixth gravity models for testing the deployment mechanism; a one-gravity trainer to give the astronauts instruction in the operation of the rover and allow them to practice driving it; a mass model to test the effect of the rover on the LM structure, balance, and handling; a vibration test unit to study the LRV’s durability and handling of launch stresses; and a qualification test unit to study integration of all LRV subsystems. A paper by Savero Morea gives details of the LRV system and its development.

The Apollo Lunar Roving Vehicle was an electric-powered vehicle designed to operate in the low-gravity vacuum of the Moon and to be capable of traversing the lunar surface, allowing the Apollo astronauts to extend the range of their surface extravehicular activities. The mission commander served as the driver, occupying the left-hand seat of each LRV.

The Lunar Roving Vehicle had a mass of 460 pounds (210 kg), and was designed to hold a payload of 1,080 pounds (490 kg). This resulted in weights in the approximately one-sixth g on the lunar surface of 77 pounds-force (35 kgf) empty and 260 pounds-force (116 kgf) fully loaded. The frame was 10 feet (3.0 m) long with a wheelbase of 7.5 feet (2.3 m). The height of the vehicle was 3.6 feet (1.1 m). The frame was made of 2219 aluminium alloy tubing welded assemblies and consisted of a three-part chassis that was hinged in the center so it could be folded up and hung in the Lunar Module Quadrant 1 bay. It had two side-by-side foldable seats made of tubular aluminium with nylon webbing and aluminum floor panels. An armrest was mounted between the seats, and each seat had adjustable footrests and a Velcro-fastened seat belt. A large mesh dish antenna was mounted on a mast on the front center of the rover. The suspension consisted of a double horizontal wishbone with upper and lower torsion bars and a damper unit between the chassis and upper wishbone. Fully loaded, the LRV had a ground clearance of 14 inches (36 cm).

The wheels were designed and manufactured by General Motors Defense Research Laboratories in Santa Barbara, California. Ferenc Pavlics was given special recognition by NASA for developing the “resilient wheel”. They consisted of a spun aluminum hub and a 32 inches (81 cm) diameter, 9 inches (23 cm) wide tire made of zinc-coated woven 0.033 inches (0.84 mm) diameter steel strands attached to the rim and discs of formed aluminum. Titanium chevrons covered 50% of the contact area to provide traction. Inside the tire was a 25.5 inches (65 cm) diameter bump stop frame to protect the hub. Dust guards were mounted above the wheels. Each wheel had its own electric drive made by Delco, a direct current (DC) series-wound motor capable of 0.25 horsepower (190 W) at 10,000 rpm, attached to the wheel via an 80:1 harmonic drive, and a mechanical brake unit.

Maneuvering capability was provided through the use of front and rear steering motors. Each series-wound DC steering motor was capable of 0.1 horsepower (75 W). The front and rear wheels would turn in opposite directions to achieve a tight turning radius of 10 feet (3 m), or could be decoupled so only front or rear would be used for steering. They could free-wheel in case of drive failure.

Power was provided by two 36-volt silver-zinc potassium hydroxide non-rechargeable batteries with a capacity of 121 A·h each (a total of 242 A·h), yielding a range of 57 miles (92 km). These were used to power the drive and steering motors and also a 36-volt utility outlet mounted on the front of the LRV to power the communications relay unit or the TV camera. LRV batteries and electronics were passively cooled, using change-of-phase wax thermal capacitor packages and reflective, upward-facing radiating surfaces. While driving, radiators were covered with mylar blankets to minimize dust accumulation. When stopped, the astronauts would open the blankets, and manually remove excess dust from the cooling surfaces with hand brushes.

A T-shaped hand controller situated between the two seats controlled the four drive motors, two steering motors, and brakes. Moving the stick forward powered the LRV forward, left and right turned the vehicle left or right, and pulling backwards activated the brakes. Activating a switch on the handle before pulling back would put the LRV into reverse. Pulling the handle all the way back activated a parking brake. The control and display modules were situated in front of the handle and gave information on the speed, heading, pitch, and power and temperature levels.

Navigation was based on continuously recording direction and distance through use of a directional gyro and odometer and feeding this data to a computer that would keep track of the overall direction and distance back to the LM. There was also a Sun-shadow device that could give a manual heading based on the direction of the Sun, using the fact that the Sun moved very slowly in the sky.

The LRV greatly expanded the range of the lunar explorers. Previous teams of astronauts were restricted to short walking distances around the landing site due to the bulky space suit equipment required to sustain life in the lunar environment. The range, however, was operationally restricted to remain within walking distance of the lunar module, in case the rover broke down at any point. The rovers were designed with a top speed of about 8 mph (13 km/h), although Eugene Cernan recorded a maximum speed of 11.2 mph (18.0 km/h), giving him the (unofficial) lunar land-speed record.

An operational constraint on the use of the LRV was that the astronauts must be able to walk back to the LM if the LRV were to fail at any time during the EVA (called the “Walkback Limit”). Thus, the traverses were limited in the distance they could go at the start and at any time later in the EVA. Therefore, they went to the farthest point away from the LM and worked their way back to it so that, as the life support consumables were depleted, their remaining walk back distance was equally diminished.

Deployment of the LRV from the LM’s Quadrant 1 bay by the astronauts was achieved with a system of pulleys and braked reels using ropes and cloth tapes. The rover was folded and stored in the bay with the underside of the chassis facing out. One astronaut would climb the egress ladder on the LM and release the rover, which would then be slowly tilted out by the second astronaut on the ground through the use of reels and tapes. As the rover was let down from the bay, most of the deployment was automatic. The rear wheels folded out and locked in place. When they touched the ground, the front of the rover could be unfolded, the wheels deployed, and the entire frame let down to the surface by pulleys.

The rover components locked into place upon opening. Cabling, pins, and tripods would then be removed and the seats and footrests raised. After switching on all the electronics, the vehicle was ready to back away from the LM.

The LRV was developed in only 17 months and performed all its functions on the Moon with no major anomalies. Scientist-astronaut Harrison Schmitt of Apollo 17 said, “The Lunar Rover proved to be the reliable, safe and flexible lunar exploration vehicle we expected it to be. Without it, the major scientific discoveries of Apollo 15, 16, and 17 would not have been possible; and our current understanding of lunar evolution would not have been possible.”

After unloading the Lunar Roving Vehicle (LRV) on July 31, 1971, Scott and Irwin drove to the first moonwalk’s primary destination, Elbow Crater, along the edge of Hadley Rille. On returning to the LM Falcon, Scott and Irwin deployed the Apollo Lunar Surface Experiments Package (ALSEP). The first EVA lasted about 6½ hours.

The target of the second EVA, the next day, was the edge of Mount Hadley Delta, where the pair sampled boulders and craters along the Apennine Front. During this moonwalk, the astronauts recovered what came to be one of the more famous lunar samples collected on the Moon during Apollo, sample #15415, more commonly known as the “Genesis Rock.” Once back at the landing site, Scott continued to try to drill holes for an experiment at the ALSEP site, with which he had struggled the day before. After conducting soil-mechanics experiments and erecting a U.S. flag, Scott and Irwin returned to the LM. EVA 2 lasted 7 hours and 12 minutes.

During EVA 3, the third and final moonwalk of the mission, the crew again ventured to the edge of Hadley Rille, this time to the northwest of the immediate landing site. After returning to the LM’s location, Scott performed an experiment in view of the television camera, using a feather and hammer to demonstrate Galileo’s theory that all objects in a given gravity field fall at the same rate, regardless of mass (in the absence of aerodynamic drag). He dropped the hammer and feather at the same time; because of the negligible lunar atmosphere, there was no drag on the feather, which hit the ground at the same time as the hammer.

Scott then drove the rover to a position away from the LM, where the television camera could be used to observe the lunar liftoff. Before the mission, the crew had contacted Belgian sculptor Paul Van Hoeydonck to create a small aluminum statuette called “Fallen Astronaut” to commemorate those astronauts and cosmonauts who lost their lives in the pursuit of space exploration. Scott left the sculpture by the rover, along with a plaque bearing the names of 14 known American astronauts and Soviet cosmonauts deceased by that time. The memorial was left while the television camera was turned off; only Irwin knew what Scott was doing at the time. Scott told mission control he was doing some cleanup activities around the rover.

The EVA lasted 4 hours and 50 minutes. In total, the two astronauts spent 18½ hours outside the LM and collected approximately 170 pounds (77 kg) of lunar samples.

After lifting off from the lunar surface 2 days and 18 hours after landing, the LM ascent stage rendezvoused and re-docked with the CSM with Worden aboard in orbit. After transferring samples and other items from the LM to the CSM, the LM was sealed off, jettisoned, and intentionally crashed into the lunar surface. After completing more observations of the Moon from orbit and releasing the sub-satellite, the three-person crew departed lunar orbit with another burn of the SPS engine.

The next day, on the return trip to Earth, Worden performed a spacewalk in deep space, the first of its kind, to retrieve exposed film from the SIM bay. Later on in the day, the crew set a record for the longest Apollo flight to that point.

On approach to Earth the next day, August 7, the Service Module was jettisoned, and the Command Module (CM) reentered the Earth’s atmosphere. Although one of the three parachutes on the CM failed to deploy properly, only two were required for a safe landing (one extra for redundancy). Upon landing in the North Pacific Ocean, the crew were recovered and taken aboard the recovery ship, USS Okinawa after a mission lasting 12 days, 7 hours, 11 minutes, and 53 seconds.

Endeavour is currently on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio. The rover used on Apollo 15 was left on the lunar surface at Hadley-Apennine ( 26.10°N 3.65°E ).

After a successful mission, the reputations of the crew and NASA were tarnished by a deal the crew had made with a German stamp dealer. H. Walter Eiermann, who had many professional and social contacts with NASA employees and the astronaut corps, arranged for Scott to carry unauthorized commemorative postal covers in his space suit, in addition to the postal covers NASA had contracted to carry for the United States Postal Service. Eiermann had promised each astronaut $7,000 in the form of savings accounts in return for 100 covers signed after having been on the Moon. He told the astronauts that he would not advertise or sell the covers until the end of the Apollo program. Irwin wrote in his book To Rule the Night that the astronauts had agreed to the deal as a way to help finance their children’s college tuition.

The crew of Apollo 15 took 398 unauthorized commemorative postage stamp covers with them on their trip to the Moon (400 were printed, but two were damaged and destroyed prior to being packaged), with the understanding that, when they returned, 100 of the covers were to be sold to the German stamp dealer who provided them. Those 100 covers are known today by philatelists as the “Sieger covers”, named such after the dealer, Hermann Sieger. The remaining 298 covers were to be kept by the crew members as souvenirs but were later confiscated by NASA when the public sale of Sieger’s covers was discovered soon after the mission. The crew’s 298 covers were not returned until 1983, after the astronauts filed suit against the government for their return, citing NASA’s partnership with the U.S. Postal Service to sell covers flown on the Space Shuttle.

Although taking souvenirs into space was not illegal nor prohibited by NASA at the time — the Apollo 15 crew had 243 authorized covers on board in addition to the 398 unauthorized covers — the discovery of the Sieger covers’ sale caused Congress to take notice and led to NASA taking disciplinary action against several Apollo astronauts, including Apollo 15 commander David Scott, who admitted to carrying the stamps, and Jack Swigert, who was not involved in the incident directly but was less than forthcoming when asked to provide information to investigators about the practice of carrying souvenirs aboard spacecraft. Scott was already working on the docking system for the upcoming Apollo-Soyuz Test Project. Apollo 15 crewmember Alfred Worden was reassigned to a non-flight role within NASA and crewmember James Irwin resigned to pursue a Christian ministry in Colorado Springs, Colorado. Congressional questioning of NASA officials over the affair was a further source of embarrassment for the agency.

While Scott and his crewmates were preoccupied with their final training for the mission, a controversy developed within NASA and Congress over some of the souvenir silver medallions that the crew of Apollo 14 had carried to the moon with them. Before the mission an agreement had been reached with the Franklin Mint that some of the medallions were to be melted down upon the return to Earth and sold as souvenirs; the mint had even promoted this in ads. But it was never finalized; however, Astronaut Corps commander Deke Slayton reduced the number of medallions each member of Apollo 15 could take along by half.

One night several months before launch, Slayton introduced Scott and the crew to Hermann Sieger, a German stamp dealer, who proposed that they supplement their income by signing some first day covers for the launch date. They would not be sold, the astronauts were told, until some time in the future after the Apollo program had ended. Other Apollo crews had made, and profited from, similar agreements. Since they were not permitted to buy life insurance, the astronauts felt that the proceeds might be a good substitute, and agreed to the deal, putting the proceeds into a trust fund for their children’s education.

The crew took 398 covers to the moon with them (two of the planned 400 were damaged). Later it was alleged that these had been smuggled on board. In his 2013 book Two Sides of the Moon, Scott says that was impossible as the astronauts had to account for everything they took on board, including personal items. Instead of personally certifying the Apollo 15 crews as he usually did, Slayton deferred to the flight-support crew, according to Scott. The support team’s manifest did not include the covers.

Once the mission was over, a German stamp dealer began selling the first day covers immediately. The astronauts objected and said they did not want the money. When the sales were reported in the press, some members of Congress became angry that they heard about them first that way, instead of from NASA itself, especially in the wake of the Apollo 14 medallion incident. Slayton claimed in his autobiography that he felt that Scott, Worden and Irwin had embarrassed NASA and the Apollo program by trying to profit in such way from the hard work that had gone into the Apollo 15 mission, and violated NASA rules.

However, they were not expelled from the astronaut corps, as some reports claimed at the time. Scott wrote later that a “witch hunt” mentality took hold. The astronauts were advised to retain independent legal counsel before testifying at a closed Senate hearing on the matter. “NASA had hung us out to dry,” Scott wrote. Despite an expectation that they, too, would refuse to talk and invoke their Fifth Amendment rights at the hearing, “we told it like it was. We had nothing to hide.”

A few years later Scott retired from the Air Force, and then left NASA. In 1978, the Justice Department concluded that while the crew had broken some space-agency rules, they did nothing illegal. The covers were legal, they had not been intended for sale, the crew had not smuggled them on board and NASA would have approved letting them do so had they been asked. “We were reprimanded and took our licks. But it was a very raw deal,” recalls Scott. There had been complaints about the deals undertaken by previous missions, but “the wave reached the shore on Apollo 15 and we were the ones who bore the brunt of the blame for such incidents.”

The market value of these postal covers has climbed steadily over the years, given their rarity and broad appeal to both space and stamp collectors. As an example, one Apollo 15 postal stamped cover sold at the January 2008 Novaspace auction for U.S. $15,000, and a second sold in 2014 for over $55,000.

View of Commemorative plaque left on moon at Hadley-Apennine landing site. A close-up view of a commemorative plaque left on the Moon at the Hadley-Apennine landing site in memory of 14 NASA astronauts and USSR cosmonauts, now deceased. Their names are inscribed in alphabetical order on the plaque. The plaque was stuck in the lunar soil by Astronauts David R. Scott and James B. Irwin during their Apollo 15 lunar surface extravehicular activity. The tiny, man-like object represents the figure of a fallen astronaut/cosmonaut. (August 1, 1971)
View of Commemorative plaque left on moon at Hadley-Apennine landing site. A close-up view of a commemorative plaque left on the Moon at the Hadley-Apennine landing site in memory of 14 NASA astronauts and USSR cosmonauts, now deceased. Their names are inscribed in alphabetical order on the plaque. The plaque was stuck in the lunar soil by Astronauts David R. Scott and James B. Irwin during their Apollo 15 lunar surface extravehicular activity. The tiny, man-like object represents the figure of a fallen astronaut/cosmonaut. (August 1, 1971)

Another controversy arose after the flight, caused by the “Fallen Astronaut” statuette that Scott had left on the Moon. The crew claim they had agreed with the sculptor, Paul Van Hoeydonck, that no replicas were to be made, in order to satisfy NASA’s aversion to commercial exploitation of the space program. After the sculpture’s existence was publicly disclosed during their post-flight press conference, the National Air and Space Museum contacted the crew asking for a replica made for the museum. Van Hoeydonck, whose account of the agreement contradicts Scott’s, subsequently advertised replicas for sale to the public. Under pressure from NASA, Van Hoeydonck withdrew the sale offer.

The halo area of the Apollo 15 landing site, generated by the LM’s exhaust plume, was observed by a camera aboard the Japanese lunar orbiter SELENE and confirmed by comparative analysis of photographs in May 2008. This corresponds well to photographs taken from the Apollo 15 Command Module showing a change in surface reflectivity due to the plume, and was the first visible trace of manned landings on the Moon seen from space since the close of the Apollo program.

Two 8-cent setenant stamps commemorating a decade of space achievements were placed on sale August 2, 1971, at Kennedy Space Center, Florida, and Houston, Texas (Scott #1434-1435). First day covers were postmarked at two different post offices (Houston, Texas and Huntsville, Alabama, location of the two tracking stations) rather than the usual one because of extraordinary popularity of the space program at the time of issuance. This ‘Space Achievements’ issue depicts the Earth, Sun, Lunar Module, the Lunar Rover and astronauts. The stamps were designed by Robert T. McCall of Paradise Valley, Arizona. Upon close examination, one can see that it has an accurate depiction of the Lunar Rover, sitting on the Lunar surface. The Lunar Landing Module can also be seen in the background. The stamps were lithographed and engraved by the Bureau of Printing and Engraving, perforated 11, and printed in sheets of 50, with an total printing of 88,147,500.



  1. I am a big fan of space stuff. I even thought about ordering a collection of Space stamps from Amazon–I could be a topic collector….someday. I balked when I saw the price differential between Canada and the US.
    Some other time perhaps.
    I enjoyed this post.


    1. These days, I can only dream. I once had a great collection of space-themed (mostly NASA) collectibles including lots of flight covers (plenty of autographs especially of the latter Apollo flights, Apollo-Soyuz, SkyLab, and early Shuttle test flights, etc.). Alas, most was sold upon my move to Thailand for a lot less than they would go for now. All I kept was my autographed photo of Neil Armstrong (obtained in person circa 1979-1980) and I’m holding onto that…

      Liked by 1 person

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.