Apollo 15

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Apollo 15
Apollo 15 flag, rover, LM, Irwin.jpg
Jim Irwin salutes the United States flag on the Moon, August 1, 1971
Mission typeManned lunar landing
OperatorNASA[1]
COSPAR ID
  • CSM: 1971-063A
  • LM: 1971-063C
SATCAT no.
  • CSM: 5351
  • LM: 5366
Mission duration12 days, 7 hours, 11 minutes, 53 seconds
Spacecraft properties
Spacecraft
Manufacturer
Launch mass48,599 kilograms (107,142 lb)
Landing mass5,321 kilograms (11,731 lb)
Crew
Crew size3
Members
Callsign
  • CSM: Endeavour
  • LM: Falcon
EVAs1 in cislunar space
Plus 4 on the lunar surface
EVA duration39 minutes, 7 seconds
Spacewalk to retrieve film cassettes
Start of mission
Launch dateJuly 26, 1971, 13:34:00.6 (1971-07-26UTC13:34Z) UTC
RocketSaturn V AS-510[2]
Launch siteKennedy LC-39A
End of mission
Recovered byUSS Okinawa
Landing dateAugust 7, 1971, 20:45:53 (1971-08-07UTC20:45:54Z) UTC
Landing siteNorth Pacific Ocean
26°7′N 158°8′W / 26.117°N 158.133°W / 26.117; -158.133 (Apollo 15 splashdown)
Orbital parameters
Reference systemSelenocentric
Periselene101.5 kilometers (54.8 nmi)
Aposelene120.8 kilometers (65.2 nmi)
Inclination23 degrees
EpochJuly 30, 1971
Lunar orbiter
Spacecraft componentCommand and service module
Orbital insertionJuly 29, 1971, 20:05:46 UTC
Orbital departureAugust 4, 1971, 21:22:45 UTC
Orbits74
Lunar lander
Spacecraft componentLunar module
Landing dateJuly 30, 1971, 22:16:29 UTC
Return launchAugust 2, 1971, 17:11:23 UTC
Landing site26°07′56″N 3°38′02″E / 26.1322°N 3.6339°E / 26.1322; 3.6339[3]
Sample mass77 kilograms (170 lb)
Surface EVAs4 (including standup)
EVA duration
  • 19 hours, 7 minutes, 53 seconds
  • Standup: 33 minutes, 7 seconds
  • First: 6 hours, 32 minutes, 42 seconds
  • Second: 7 hours, 12 minutes, 14 seconds
  • Third: 4 hours, 49 minutes, 50 seconds
Lunar rover
Distance covered27.9 kilometers (17.3 mi)
Docking with LM
Docking dateJuly 26, 1971, 17:07:49 UTC
Undocking dateJuly 30, 1971, 18:13:16 UTC
Docking with LM Ascent Stage
Docking dateAugust 2, 1971, 19:10:25 UTC
Undocking dateAugust 3, 1971, 01:04:01 UTC
Payload
Mass
  • SIM:
  • LRV: 463 pounds (210 kg)
Apollo 15-insignia.png The Apollo 15 Prime Crew - GPN-2000-001169.jpg
Left to right: Scott, Worden, Irwin

Apollo 15 was the ninth manned mission in the United States' Apollo program, the eighth to be successful, and the fourth to land on the Moon. It was the first J mission, with a longer stay on the Moon and a greater focus on science than earlier landings. Apollo 15 saw the first use of the Lunar Roving Vehicle.

The mission began on July 26, 1971, and ended on August 7, with the lunar exploration taking place between July 30 and August 2. Commander David Scott and Lunar Module Pilot James Irwin spent three days on the Moon, including 18​12 hours outside the spacecraft on lunar extravehicular activity (EVA). The two astronauts landed near Hadley Rille and explored the local area using the rover, allowing them to travel much farther from the lunar module (LM) than had been possible on previous missions. Scott and Irwin collected 77 kilograms (170 lb) of lunar surface material. At the same time, Command Module Pilot Alfred Worden orbited the Moon, operating a suite of scientific instruments in the SIM bay of the service module. The instruments collected data on the Moon and its environment using a panoramic camera, a gamma-ray spectrometer, a mapping camera, a laser altimeter, a mass spectrometer, and a lunar subsatellite deployed at the end of Apollo 15's stay in lunar orbit.

The mission successfully accomplished its goals, but was marred by negative publicity the following year that the crew had carried unauthorized postal covers to the lunar surface, some of which were sold by a West German stamp dealer. The members of the crew were reprimanded for poor judgment, and did not fly in space again. Apollo 15 is also remembered for the finding of the Genesis Rock, and for Scott's use of a hammer and a feather to validate Galileo's theory that absent air resistance, objects drop at the same rate.

Background[edit]

In 1962, NASA contracted for fifteen Saturn V Moon rockets to achieve the Apollo program's goal of a manned landing on the Moon by 1970; at the time no one knew how many missions would be required to achieve this.[4] Since success was obtained with the sixth Saturn V on Apollo 11, nine rockets remained available for a plan of ten total lunar landings. These plans included a heavier, extended version of the Apollo spacecraft to be used in the last five missions (Apollo 16-20). The extensions included a package of orbital experiments carried in the service module, and an extended lunar module capable of up to 75-hour stays and carrying a Lunar Roving Vehicle to the Moon's surface. In the original plan, Apollo 15 was to be the last of the non-extended missions, to land in Censorinus crater. But in anticipation of budget cuts, NASA cancelled the last three landing missions by September 1970. Apollo 15 became the first of three extended missions, known as J missions, and the landing site was moved to Hadley Rille, originally planned for Apollo 19.[5]

Crew and key Mission Control personnel[edit]

NASA Astronaut Group 5 (1966) provided two of the Apollo 15 crew members. In the back row, Irwin is fifth from left, Worden third from right.
Position Astronaut
Commander David R. Scott[6]
Third and last spaceflight
Command Module Pilot Alfred M. Worden[6]
Only spaceflight
Lunar Module Pilot James B. Irwin[6]
Only spaceflight

Scott was born in 1932 in San Antonio, Texas, and had graduated from the United States Military Academy in 1954. Serving in the Air Force, Scott had received two advanced degrees from MIT in 1962 before being selected as one of the third group of astronauts the following year. He flew in Gemini 8 in 1966 alongside Neil Armstrong and as Command Module Pilot of Apollo 9 in 1969. Worden was born in 1932 in Jackson, Michigan and like his commander, had attended West Point (class of 1955) and served in the Air Force. Worden earned two master's degrees in engineering from the University of Michigan in 1963. Irwin had been born in 1930 in Pittsburgh, and had attended the United States Naval Academy, graduating in 1951 and serving in the Air Force, receiving a master's degree from Michigan in 1957. Both Worden and Irwin were selected in the fifth group of astronauts (1966), and Apollo 15 would be their only spaceflight.[7]

Backup crew[edit]

Backup commander Richard F. Gordon Jr. (right) and backup LMP Harrison H. Schmitt during geology training in New Mexico, March 1971
Position Astronaut
Commander Richard F. Gordon Jr.[6]
Command Module Pilot Vance D. Brand[6]
Lunar Module Pilot Harrison H. Schmitt[6]

Schmitt would be the first member of Group 4 to fly in space; he was the only astronaut from that group to make it to the Moon, with Apollo 17.[8]

Support crew[edit]

All three members of the support crew were scientist-astronauts, selected in 1967, as the prime crew felt they needed more assistance with the science than with the piloting. None of the support crew would fly during the Apollo Program, waiting until the Space Shuttle program for the chance to go into space.[9]

Flight directors[edit]

Capsule communicators (CAPCOMs)[edit]

Mission Control in Houston during the third Apollo 15 EVA, August 2, 1971. CAPCOM Joe Allen is to left (pointing) with Dick Gordon next to him

Planning and training[edit]

The three Apollo 15 astronauts had served as the backup crew to Apollo 12, and since Apollo 11's backup crew had been designated for Apollo 13 (which did not land on the Moon), they were the first Apollo crew for a successful lunar landing mission to have backed up another such mission.[12] Having had the opportunity to familiarize themselves with the Apollo spacecraft, they could devote more of their training time as prime crew for Apollo 15 to geology and sampling techniques.[ALSJ 1]

Commander David Scott takes a photograph during geology training in Hawaii, December 1970

The astronauts at NASA who were scientists, such as geologist Harrison Schmitt, pushed though the early Apollo missions for a greater place for science as part of the mission, but often there were higher priorities or astronaut disinterest. Schmitt realized that what was needed was an expert teacher who could fire the astronauts' enthusiasm, and contacted Caltech geologist Lee Silver, whom Schmitt introduced to Apollo 13 mission commander Jim Lovell and Lunar Module Pilot Fred Haise, then in training for their mission. Lovell and Haise were willing to go on a field expedition with Silver, and geology became a significant part of their training. Geologist Farouk El-Baz trained the prime crew's Command Module Pilot, Ken Mattingly to inform his planned observations from lunar orbit. The crew's newly-acquired skills mostly went unused, due to the explosion that damaged the Apollo 13 spacecraft.[a] Apollo 14's CMP, Stu Roosa, was enthusiastic about geology, but the mission commander, Alan Shepard, less so.[13]

Scott (to right) and Worden in the command module simulator during training

Scott was determined that his crew bring back the maximum amount of scientific data possible, and met with Silver in April 1970 to begin planning the geological training. The assignment of Schmitt as Apollo 15's backup LMP made him an insider, and allowed him to spark competition between the prime and backup crews. The cancellation of two Apollo missions in September 1970 transformed Apollo 15 into a J mission, with a longer stay on the lunar surface, and the first Lunar Roving Vehicle (LRV). This change was welcomed by Scott,[14] who according to David West Reynolds in his account of the Apollo Program, was "something more than a hotshot pilot. Scott had the spirit of a true explorer," one determined to get the most from the J mission.[15] The additional need for communications, including from experiments in the command module (CM) and from the rover, required the near-rebuilding of the Honeysuckle Creek Tracking Station in Australia.[16]

Geology field trips took place about once a month throughout the crew's 20 months of training. At first Silver would take the commanders and LMPs from the prime and backup crews to various geological sites in Arizona and New Mexico as if for a normal field geology lesson, but closer to launch, 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 geologist unfamiliar with the area who would rely on the astronauts' descriptions to interpret the findings, and familiarized the crew members with describing landscapes to people who could not see them.[17] Considering himself a serious amateur, Scott came to enjoy field geology.[18]

The decision to land at Hadley came in September 1970. The Site Selection Committees had narrowed the field down to two sites — Hadley Rille, a deep channel on the edge of Mare Imbrium close to the Apennine mountains 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.[19] To David Scott the choice was clear, as Hadley "had more variety. 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."[20] The selection of Hadley was made although NASA lacked high resolution images of the landing site; none had been made as the site was considered too rough to risk one of the earlier Apollo missions.[21] The proximity of the Apennine mountains required a landing approach trajectory of 26 degrees, far steeper than the 15 degrees in earlier Apollo landings.[22]

The expanded mission meant that Worden spent much of his time at North American Rockwell's facilities at Downey, California, where the command and service modules (CSM) were being built.[23] Worden undertook a different kind of geology training. Working with El-Baz, he studied maps and photographs of the craters he would pass over while orbiting alone in the CSM. As El-Baz listened and gave feedback, Worden learned how to describe lunar features in a way that would be useful to the scientists who would listen to his transmissions back on Earth. Worden found El-Baz to be an enjoyable and inspiring teacher. In addition, Worden usually accompanied his crewmates on their geology field trips, though he was often in an airplane overhead, describing features of the landscape as the plane simulated the speed at which the lunar landscape would pass below the CSM.[24]

The demands of the training strained Worden's marriage and also that of Irwin; each sought Scott's advice, fearing that divorce might endanger their places on the mission as not projecting the image NASA wanted for the astronauts. Scott consulted Director of Flight Crew Operations Deke Slayton, their boss, who stated what was important was that the astronauts do their jobs. Although the Irwins overcame their marital difficulties, Worden divorced before the mission.[25]

Mission highlights[edit]

Launch and outbound trip[edit]

Apollo 15 launches on July 26, 1971

Apollo 15 was launched on July 26, 1971, at 9:34 AM EDT from the Kennedy Space Center at Merritt Island, Florida. The time of launch was at the very start of the two hour, 37 minute launch window, which would allow Apollo 15 to arrive at the Moon with the proper lighting conditions at Hadley Rille; had the mission been scrubbed, it could not have been rescheduled until late August. The astronauts had been wakened five and a quarter hours before launch by Slayton, and after breakfast and suiting up, had been taken to Pad 39A, launch site of all seven attempts at manned lunar landing, and entered the spacecraft about three hours before launch. There were no unplanned delays in the countdown.[ALFJ 4]

At 000:11:36 into the mission, the S-IVB engine shut down, leaving Apollo 15 in its planned parking orbit in Low Earth Orbit. The mission remained there for some 2 hours and 40 minutes, allowing the crew (and Houston, via telemetry) to check the spacecraft's systems. At 002:50.02.6 into the mission, the S-IVB was restarted for trans-lunar injection (TLI), placing the craft on a path to the Moon.[ALFJ 4][ALFJ 5] Prior to TLI, the craft had completed 1.5 orbits around the Earth.[26]

Astronaut Al Worden maneuvers the CSM to a docking with the lunar module Falcon

The command and service module (CSM) and the lunar module remained attached to the nearly-exhausted S-IVB booster. Once trans-lunar injection had been achieved, placing the spacecraft on a trajectory towards the Moon, explosive cords separated the CSM from the booster as Worden operated the CSM's thrusters to push it away. Worden then maneuvered the CSM to dock with the LM (mounted on the end of the S-IVB), and the combined craft was then separated from the S-IVB by explosives. After Apollo 15 separated from the booster, the S-IVB maneuvered away, and would impact the Moon about an hour after the crewed spacecraft entered lunar orbit, though due to an error the impact was 79 nautical miles (146 km) away from the intended target.[ALFJ 6] The booster's impact was detected by the seismometers left on the Moon by Apollo 12 and Apollo 14, providing useful scientific data.[27]

There was a malfunctioning light on the craft's service propulsion system (SPS); after considerable troubleshooting, the astronauts did a test burn of the system that also served as a midcourse correction. This occurred about 028:40:00 into the mission. Fearing that the light meant the SPS might unexpectedly fire, the astronauts avoided using the control bank that had the faulty light, bringing it online only for major burns, and controlling it manually. After the mission returned, the malfunction proved to be caused by a tiny bit of wire trapped within the switch.[ALFJ 7][28]

Endeavour, as seen from the lunar module Falcon

After purging and renewing the LM's atmosphere to eliminate any contamination, the astronauts entered the LM about 34 hours into the mission, needing to check the condition of its equipment and move in items that would be required on the Moon. Much of this work was televised back to Earth, the camera operated by Worden. The crew discovered a broken outer cover on the Range/Range rate tapemeter. This was a concern not only because an important piece of equipment might not work properly, but because bits of the glass cover were floating around Falcon's interior.[ALFJ 8] The tapemeter was supposed to be in a helium atmosphere, but due to the breakage, it was in the LM's oxygen atmosphere. Testing on the ground verified the tapemeter would still work properly, and the crew removed most of the glass using a vacuum cleaner and adhesive tape.[ALFJ 8][29]

As yet, there had been only minor problems, but at about 61:15:00 mission time (the evening of July 28 in Houston), Scott discovered a leak in the water system while preparing to chlorinate the water supply. The crew could not tell where it was coming from, and the issue had the potential to become serious. The experts in Houston found a solution, which was successfully implemented by the crew. The water was mopped up with towels, which were then put out to dry in the tunnel between the command module and lunar module—Scott stated it looked like someone's laundry.[ALFJ 9]

At 73:31:14 into the mission, a second midcourse correction, with less than a second of burn, was made. Although there were four opportunities to make midcourse corrections following TLI, only two needed to be used. Apollo 15 approached the Moon on July 29, and the lunar orbit insertion (LOI) burn had to be made using the SPS, on the far side of the Moon, out of radio contact with Earth. If no burn occurred, Apollo 15 would emerge from the lunar shadow and come back in radio contact faster than expected; the continued lack of communication allowed Mission Control to conclude that the burn had taken place. When contact resumed, Scott did not immediately give the particulars of the burn, but spoke admiringly of the beauty of the Moon, causing Alan Shepard, the Apollo 14 commander, who was awaiting a television interview, to grumble, "To hell with that shit, give us details of the burn."[ALFJ 10] The 398.36-second burn took place at 078:31:46.7 into the mission at an altitude of 86.7 nautical miles (160.6 km) above the Moon, and placed Apollo 15 in an elliptical lunar orbit of 170.1 by 57.7 nautical miles (315.0 by 106.9 km).[29]

Lunar orbit and landing[edit]

The interior of Falcon

On Apollo 11 and 12, the lunar module decoupled from the CSM and descended to a much lower orbit from which the lunar landing attempt commenced; to save fuel in an increasingly heavy lander, beginning with Apollo 14, the SPS in the service module made that burn, known as descent orbit insertion (DOI), with the lunar module still attached to the CSM. The initial orbit Apollo 15 was in had its apocynthion, or high point, over the landing site at Hadley; a burn at the opposite point in the orbit was performed, with the result that Hadley would now be under the craft's pericynthion, or low point.[ALFJ 11] The DOI burn was performed at 082:39:49.09 and took 24.53 seconds; the result was an orbit with apocynthion of 58.5 nmi and pericynthion of 9.6 nmi.[30] Overnight between July 29 and 30, as the crew rested, it became apparent to Mission Control that mass concentrations in the Moon were making Apollo 15's orbit increasingly elliptical—pericynthion was 7.6 nmi by the time the crew was awakened on July 30. This, and uncertainty as to the exact altitude of the landing site, made it desirable that the orbit be modified, or trimmed. Using the craft's RCS thrusters,[ALFJ 3] this took place at 095:56:44.70, lasting 30.40 seconds, and raised the pericynthion to 8.8 nmi and the apocynthion to 60.2 nmi.[30]

In addition to preparing the lunar module for its descent, the crew continued observations of the Moon (including of the landing site at Hadley) and provided television footage of the surface. Undocking was planned for 100:13:56, over the far side of the Moon, but nothing happened when separation was attempted.[ALFJ 12] After analyzing the problem, the crew and Houston decided the probe instrumentation umbilical was likely loose or disconnected; Worden went into the tunnel connecting the command and lunar modules and determined this was so, seating it more firmly. With the problem resolved, Falcon separated from Endeavour at 100:39:16.2, about 25 minutes late, at an altitude of 7.4 nmi. Worden in Endeavour executed a SPS burn at 101:38:58.98 to send Endeavour to an orbit of 65.2 x 54.8 nmi in preparation for his scientific work.[31]

Aboard Falcon, Scott and Irwin prepared for powered descent initiation (PDI), the burn that was to place them on the lunar surface, and, after Mission Control gave them permission,[ALSJ 2] they initiated PDI at 104:30:09.4 at an altitude of 5.8 nmi,[31] slightly higher than planned. During the first part of the descent, Falcon was aligned so that the astronauts were on their backs and thus could not see the lunar surface below them, but after the craft made a pitchover maneuver, they could see the surface in front of them. Scott, who as commander performed the landing, was confronted with a landscape that did not at first seem to resemble what he had seen during simulations. Part of this was due to an error in the landing path of some 3,000 feet (910 m), of which the CAPCOM, Ed Mitchell informed the crew prior to pitchover; part because the craters Scott had relied on in the simulator were difficult to make out under lunar conditions, and he initially could not see Hadley Rille. He concluded that they were likely to overshoot the planned landing site, and, once he could see the rille, started maneuvering the vehicle to move the computer's landing target back towards the planned spot, and looked for a relatively smooth place to land.[ALSJ 2][32]

Below about 60 feet (18 m), Scott could see nothing of the surface because of the quantities of lunar dust being displaced by Falcon's exhaust. Falcon had a larger engine bell than previous LMs, in part to accommodate a heavier load, and the importance of shutting down the engine rather than risk "blowback", the exhaust reflecting off the lunar surface and going back into the engine (possibly causing an explosion) had been impressed on the astronauts by mission planners. Thus, when Irwin called "Contact", indicating that one of the probes on the landing leg extensions had touched the surface, Scott immediately shut off the engine. Scott's speed resulted in what was likely the hardest lunar landing of any of the manned missions, at about 6.8 feet (2.1 m) per second, causing a startled Irwin to yell "Bam!" Scott had landed Falcon on the rim of a small crater he could not see, and the lander settled back at an angle of 6.9 degrees and to the left of 8.6 degrees.[ALSJ 2] Irwin described it in his autobiography as the hardest landing he had ever been in, and he feared that the craft would keep tipping over, forcing an immediate abort.[33] Falcon landed at 104:42:29.3 (22:16:29 GMT on July 30), with approximately 103 seconds of fuel remaining, about 1,800 feet (550 m) from the planned landing site.[31] After Irwin's exclamation, Scott reported, "Okay, Houston. The Falcon is on the Plain at Hadley."[b][ALSJ 2] Despite some initial uncertainty as to where Falcon had landed, Scott was certain he had put his ship down well within the designated landing zone.[34]

Lunar surface[edit]

First EVA[edit]

As I stand out here in the wonders of the unknown at Hadley, I sort of realize there's a fundamental truth to our nature. Man must explore. And this is exploration at its greatest.

David Scott, upon setting foot on the Moon.[ALSJ 3]

With Falcon due to remain on the lunar surface for almost three days, Scott deemed it important to maintain the circadian rhythm they were used to, and as they had landed in the late afternoon, Houston time, the two astronauts were to sleep before going onto the surface. But the time schedule allowed Scott to open the lander's top hatch (usually used for docking) and spend a half hour looking at their surroundings, describing them, and taking photographs. Lee Silver had taught him the importance of going to a high place to survey a new field site, and the top hatch of the Falcon served that purpose.[35][ALSJ 2][ALSJ 4] Deke Slayton and other managers had initially been in opposition, due to the oxygen that would be lost, but Scott got his way.[36] During the only stand-up extravehicular activity (stand-up EVA) ever performed through the top hatch on the lunar surface, Scott was able to make plans for the following day's EVA.[37] He offered Irwin a chance to look out as well, but this would have required rearranging the umbilicals connecting Irwin to the Falcon's life support system, and he declined.[38] After repressurizing the spacecraft, Scott and Irwin removed their spacesuits for sleep, becoming the first astronauts to doff their suits while on the Moon.[39]

Throughout the sleep period Mission Control in Houston monitored a slow but steady oxygen loss. Scott and Irwin eventually were awakened an hour early, and the source of the problem was found to be an open valve on the urine transfer device. In post-mission debriefing, Scott recommended that future crews be woken at once under similar circumstances. After the problem was solved, the crew began preparation for the first Moon walk.[ALSJ 5]

Map of Apollo 15's traverses (landing site marked by an "x")

After donning their suits and depressurizing the cabin,[ALSJ 6] Scott and Irwin began their first full EVA, becoming the seventh and eighth humans, respectively, to walk on the Moon.[40] They attempted to deploy the lunar rover, stored folded up on the outside of Falcon's descent stage, but this proved troublesome due to the slant of the lander. The experts in Houston suggested lifting the front end of the rover as the astronauts pulled it out, and this worked.[41] One of the batteries gave a zero voltage reading, but this proved to be an instrumentation problem. A greater concern was that the front wheel steering would not work, but the rear wheel steering was sufficient to maneuver the vehicle.[42] The rover carried a television camera, controlled remotely from Houston by NASA's Ed Fendell. The resolution was not high compared to the still photographs that would be taken, but the camera allowed the geologists on Earth to indirectly participate in Scott and Irwin's activities.[43]

The rille was not visible from the landing site, but as Scott and Irwin drove over the rolling terrain, it came into view,[44] They were able to see Elbow Crater, and they began to drive in that direction.[ALSJ 7] Reaching Elbow, a known location, allowed Mission Control to backtrack and get closer to pinpointing the location of the lander. The astronauts took samples there,[45] and then drove to another crater on the flank of Mt. Hadley Delta, where they took more samples. After concluding this stop, they returned to the lander to drop off their samples and prepare to set up the Apollo Lunar Surface Experiments Package (ALSEP), the scientific instruments that would remain when they left.[46] Scott had difficulty drilling the holes required for the heat flow experiment, and the work was not completed when they had to return to the lander.[47] The first EVA lasted about 6​12 hours.[34][ALSJ 8]

Second and third EVAs[edit]

The Genesis Rock

The target of the second EVA, the next day, was the edge of Mt. Hadley Delta, where the pair sampled boulders and craters along the Apennine Front. They spent an hour at Spur Crater, during which the astronauts secured 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." This rock, an anorthosite, is believed to be part of the early lunar crust—the hope of finding such a specimen had been one reason the Hadley area had been chosen. Once back at the landing site, Scott continued to try to drill holes for experiments 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.[34][ALSJ 8]

Although Scott had eventually been successful at drilling the holes, he and Irwin had been unable to retrieve a core sample, and this was an early order of business during EVA 3, the third and final moonwalk of the mission. Time that could have been devoted to geology ticked away as Scott and Irwin attempted to pull it out. Once it had been retrieved, more time passed as they attempted to break the core into pieces for transport to Earth. Handicapped by an incorrectly-mounted vise on the rover, they eventually gave up on this—the core would be transported home in longer segments. Scott wondered if the core was worth the amount of time and effort invested, and the CAPCOM, Joe Allen, assured him that it was. The core proved one of the most important items brought back from the Moon, revealing much about its history, but the expended time meant the planned visit to a group of craters known as the North Complex had to be scrubbed. Instead, the crew again ventured to the edge of Hadley Rille, this time to the northwest of the immediate landing site.[ALSJ 8]

Scott examines a boulder during the third EVA

After the astronauts returned to the LM, Scott used a kit provided by the Postal Service to cancel a first day cover of two stamps being issued on August 2, the current date.[ALSJ 9][48] Scott then 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. This was Joe Allen's idea (he also served as CAPCOM during it) and was part of an effort to find a memorable popular science experiment to do on the Moon along the lines of Shepard's hitting of two golf balls. The feather was from a falcon, a mascot at the United States Air Force Academy—all three Apollo 15 astronauts served in the Air Force.[ALSJ 9]

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 away; he told Mission Control he was doing some cleanup activities around the rover. Scott disclosed the memorial in a post-flight news conference. He also left a bible on the control panel of the rover before leaving it for the last time to enter the LM.[ALSJ 9]

The EVA lasted 4 hours and 50 minutes.[34][ALSJ 8] In total, the two astronauts spent 18​12 hours outside the LM and collected approximately 77 kg (170 lb) of lunar samples.[ALSJ 8]

Command module activities[edit]

After the departure of Falcon, Worden in Endeavour executed a burn to take the CSM to a higher orbit.[ALFJ 12] While Falcon was on the Moon, the mission effectively split, with Worden and the CSM given their own CAPCOM and flight support team.[ALFJ 13]

Tsiolkovskiy crater on the far side of the Moon. Taken by Al Worden towards the end of the 13th orbit. The object on the left of the picture is a CSM thruster.

Worden got busy with the tasks that were to occupy him for much of the time he spent in space alone: photography and operating the instruments in the SIM bay.[ALFJ 13] The door to the SIM bay had been explosively jettisoned during the translunar coast. Filling previously-unused space in the service module, the SIM bay contained a gamma-ray spectrometer, mounted on the end of a boom, an X-ray spectrometer and a laser altimeter, which failed part way through the mission. Two cameras, a stellar camera and a metric camera, together comprised the mapping camera, which was complimented by a panoramic camera, derived from spy technology. The altimeter and cameras permitted the exact time and location from which pictures were taken to be determined. Also present were an alpha particle spectrometer, which could be used to detect evidence of lunar volcanism, and a mass spectrometer, also on a boom in the hope it would be unaffected by contamination from the ship. The boom would prove troublesome, as Worden would not always be able to get it to retract.[28]

Endeavour was slated to pass over the landing site at the moment of planned landing,[ALFJ 12] but Worden could not see Falcon[ALSJ 2] and did not spot it until a subsequent orbit. He also exercised to avoid muscle atrophy, and Houston kept him up to date on Scott and Irwin's activities on the lunar surface. The panoramic camera did not operate perfectly, but provided enough images that no special adjustment was made. Worden took many photographs through the command module's windows, often with shots taken at regular intervals. His task was complicated by the lack of a working mission timer in the Lower Equipment Bay of the command module, as its circuit breaker had popped en route to the Moon.[ALFJ 13] Worden's observations and photographs would inform the decision to send Apollo 17 to Taurus-Littrow to search for evidence of volcanic activity. There was a communications blackout when the CSM passed over the far side of the Moon from Earth; Worden greeted each resumption of contact with the words, "Hello, Earth. Greetings from Endeavour", expressed in different languages. Worden and El-Baz had come up with the idea, and the geology instructor had aided the astronaut in accumulating translations.[ALFJ 14]

Results from the SIM bay experiments would include the conclusion, from data gathered by the X-ray spectrometer that the lunar mares were rich in magnesium, with the highlands containing much aluminum.[34] Endeavour was in a more inclined orbit than previous manned missions, and Worden saw features that were not known previously, supplementing photographs with thorough descriptions.[49]

By the time Scott and Irwin were ready to take off from the lunar surface and return to Endeavor, the CSM's orbit had drifted due to the rotation of the Moon, and a plane change burn was required to ensure that the CSM's orbit would be in the same plane as that of the LM once it took off from the Moon. Worden accomplished the 18-second burn with the SPS.[ALFJ 15]

Return to Earth[edit]

The Moon as seen from the departing Apollo 15 spacecraft

Falcon lifted off the Moon at 17:11:22 UTC on August 2 after 66 hours and 55 minutes on the lunar surface. Docking with the CSM took place just under two hours later.[50] After the astronauts transferred samples and other items from the LM to the CSM, the LM was sealed off, jettisoned, and intentionally crashed into the lunar surface.[ALFJ 2] The jettison proved difficult because of problems getting airtight seals, requiring a delay in discarding the LM. After the jettison, Slayton came on the loop to recommend that the astronauts take sleeping pills, or at least that Scott and Irwin do so. Scott as mission commander refused to allow it, feeling there was no need. During the EVAs, the doctors had noticed irregularities in the heartbeats of both Scott and Irwin, of which the crew was not informed during the flight. Irwin had heart problems after retiring as an astronaut and died in 1991 of a heart attack; Scott felt that he as commander should have been informed of the biomedical readings.[28][ALFJ 2]

Apollo 15 descends with two good parachutes into the Pacific Ocean on August 7, 1971

The crew spent the next two days working on orbital science experiments, including completing more observations of the Moon from orbit and releasing the subsatellite.[49] The three-person crew departed lunar orbit with another burn of the SPS engine[ALFJ 2] of 2 minutes 21 seconds at 21:22:45 UT on August 4.[50] 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.[ALFJ 1]

On approach to Earth on August 7, the service module was jettisoned, and the command module reentered the Earth's atmosphere. Although one of the three parachutes on the CM failed to deploy properly, likely due to damage as the spacecraft vented fuel, only two were required for a safe landing (one extra for redundancy). Upon landing in the North Pacific Ocean, the CM and crew were recovered and taken aboard the recovery ship, USS Okinawa after a mission lasting 12 days, 7 hours, 11 minutes, and 53 seconds.[34][ALFJ 2]

According to David Woods in the Apollo Lunar Flight Journal,

Though subsequent missions travelled further on the Moon, brought back more samples and put the lessons of Apollo 15 into practice, this feat of unalloyed exploration still stands out as a great moment of human achievement. It is remembered still for its combination of competent enthusiasm, magnificent machinery, finely honed science and the grandeur of a very special site in the cosmos beside a meandering rille and graceful, massive mountains - Hadley Base.[28]

Hardware[edit]

Spacecraft[edit]

Command module on display at the National Museum of the United States Air Force in Dayton, Ohio

Apollo 15 used command and service module CSM-112, which was given the call sign Endeavour, named after HMS Endeavour and lunar module LM-10, call sign Falcon, named after the United States Air Force Academy mascot. Scott explained the choice of the name Endeavour on the grounds that its captain, James Cook had commanded the first purely scientific sea voyage, and Apollo 15 was the first lunar landing mission on which there was a heavy emphasis on science.[51] 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,[ALSJ 10] but the lunar module went unused and is now on display at the Kennedy Space Center Visitor Complex.[52]

Apollo 15 SM SIM bay

Technicians at the Kennedy Space Center had some problems with the instruments in the service module's SIM bay. Some instruments were late in arriving, and principal investigators or representatives of NASA contractors sought additional testing or to make small changes. Mechanical problems came from the fact the instruments were designed to operate in zero gravity, but had to be tested the surface of the Earth. As such, things like the 7.5 m (24 ft) booms for the mass and gamma ray spectrometers could only be tested using equipment that tried to mimic the space environment,[53] and so they never worked particularly well.[49] 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.[54]

Endeavour is on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio.[55]

Lunar rover[edit]

Irwin with the LRV on the Moon

A vehicle that could operate on the surface of the Moon had been considered by NASA since the early 1960s. An early version was called MOLAB, which had a closed cabin and would have massed about 6,000 pounds (2,700 kg); some scaled-down prototypes were tested in Arizona. As it became clear NASA would not soon establish a lunar base, such a large vehicle seemed unnecessary. Still, a rover would enhance the J missions, which were to concentrate on science, though its mass was limited to about 500 pounds (230 kg) and it was not then clear that so light a vehicle could be useful. NASA did not decide to proceed with a rover until May 1969, as Apollo 10, the dress rehearsal for the Moon landing, made its way home from lunar orbit. Boeing got the contract for three rovers on a cost plus basis; overruns (especially in the navigation system) meant that the three vehicles eventually cost a total of $40 million. These cost overruns gained considerable media attention at a time of greater public weariness with the space program, when NASA's budget was being cut.[ALSJ 8]

The Lunar Roving Vehicle could be folded into a space 5 ft by 20 in (1.5 m by 0.5 m). Unloaded, it weighed 460 lb (209 kg) and when carrying two astronauts and their equipment, 1500 lb (700 kg). Each wheel was independently driven by a ¼ horsepower (200 W) electric motor. Although it could be driven by either astronaut, the commander always drove. Travelling at speeds up to 6 to 8 mph (10 to 12 km/h),[ALSJ 8] it meant that for the first time the astronauts could travel far afield from their lander and still have enough time to do some scientific experiments.[54] During pre-launch testing, the LRV was given additional bracing, lest it collapse if someone sat on it under Earth conditions.[56]

Lunar subsatellite[edit]

Artist's conception of subsatellite deployment

The Apollo 15 subsatellite (PFS-1) was a small satellite released into lunar orbit from the SIM bay. Its main objectives were to study the plasma, particle, and magnetic field environment of the Moon and map the lunar gravity field. Specifically, it measured plasma and energetic particle intensities and vector magnetic fields, and facilitated tracking of the satellite velocity to high precision. A basic requirement was that the satellite acquire fields and particle data everywhere on the orbit around the Moon.[54] In addition to measuring magnetic fields, the satellite contained sensors to study the Moon's mascons.[34] The satellite orbited the Moon and returned data from August 4, 1971 until January 1973, when, following multiple failures of the subsatellite's electronics, ground support was terminated. It is believed to have crashed into the Moon sometime thereafter.[57]

In later years, through a study of many lunar orbiting satellites, scientists came to discover that most low lunar orbits (LLO) are unstable. Fortunately, PFS-1 had been placed, unknown to mission planners at the time, very near to one of only four lunar frozen orbits, where a lunar satellite may remain indefinitely.[58] A virtually identical subsatellite was deployed by Apollo 16 in April 1972, but lasted only 35 days in orbit before crashing into the Moon.[59]

Launch vehicle[edit]

Launch of Apollo 15: T-30s through T+40s.

The Saturn V that launched Apollo 15 was designated SA-510, the tenth flight-ready model of the rocket. As the payload of the rocket was greater, changes were made to the rocket and to its launch trajectory. It was launched in a more southerly direction (80–100 degrees azimuth) than that of previous missions, and the Earth parking orbit was lowered to 166 kilometers (90 nautical miles). These two changes meant 1,100 pounds (500 kg) more could be launched. The propellant reserves were reduced and the number of retrorockets on the S-IC first stage (used to separate the spent first stage from the S-II second stage) reduced from eight to four. The four outboard engines of the S-IC would be burned longer and the center engine would also burn longer before being shut down (see Saturn V for more information on the launch sequence). Changes were also made to the S-II to stop pogo oscillations.[54]

Once all the various components had been installed on the Saturn V, it was moved to the launch site, Launch Complex 39A. During late June and early July 1971, the rocket and Launch Umbilical Tower (LUT) were struck by lightning at least four times. All was well however, with only minor damage suffered.[34]

Space suits[edit]

Alfred Worden in space suit retrieving film cartridges during the transearth coast

The Apollo 15 astronauts wore redesigned space suits. On all previous Apollo flights, including the non-lunar flights, the commander and lunar module pilot had worn suits with the life support, liquid cooling, and communications connections in two parallel rows of three. On Apollo 15, the new suits, dubbed the "A7LB," had the connectors situated in triangular pairs. This new arrangement, along with the relocation of the entry zipper (which went in an up-down motion on the old suits), from the right shoulder to the left hip, aided in suiting and unseating in the cramped confines of the spacecraft. It also allowed for a new waist joint, letting the astronauts bend completely over, and also sit on the rover. Upgraded backpacks allowed for longer-duration moonwalks. Worden wore a suit similar to those worn by the Apollo 14 astronauts, but modified to interface with Apollo 15's equipment. Equipment only needed for lunar surface EVAs, such as the liquid cooling garment, was not included with Worden's suit, as the only EVA he was expected to do was one to retrieve film cartridges from the SIM bay on the flight home.[54]

Controversies[edit]

Envelope with mission patch logo, three stamps and two postmarks
A "Sieger cover"

Despite the successful mission, the careers of the crew were tarnished by a deal to carry postal covers to the moon in exchange for about $7,000 each, which they planned to set aside for their children.[60] Walter Eiermann, who had many professional and social contacts with NASA employees and the astronaut corps, served as intermediary between the astronauts and a West German stamp dealer, Hermann Sieger, and Scott carried about 400 covers onto the spacecraft; they were subsequently transferred into Falcon and remained inside the lander during the astronauts' activities on the surface of the Moon. After the return to Earth, 100 of the covers were given to Eiermann, who passed them on to Sieger, receiving a commission.[61][62] No permission had been received from Slayton to carry the covers, as required.[63]

The 100 covers were put on sale to Sieger's customers in late 1971 at a price of about $1,500 each. After receiving the agreed payments, the astronauts returned them, and accepted no compensation.[64] In April 1972, Slayton learned that unauthorized covers had been carried, and removed the three as the backup crew for Apollo 17.[63] The matter became public in June 1972 and the three astronauts were reprimanded for poor judgment;[65] none ever flew in space again.[66] During the investigation, the astronauts had surrendered those covers not sent to Eiermann; after Worden filed suit, they were returned in 1983.[67]

The Fallen Astronaut memorial, near Hadley Rille, Moon

Another controversy arose after the flight, caused by the Fallen Astronaut statuette that Scott had left on the Moon. The crew alleged they had agreed with the sculptor, Paul Van Hoeydonck, that no replicas were to be made. After the sculpture's existence was publicly disclosed during their post-flight press conference, the National Air and Space Museum obtained a replica of the sculpture and plaque for the museum. Van Hoeydonck, whose account of the agreement contradicts Scott's, subsequently advertised replicas for sale to the public.[68] Under pressure from NASA, Van Hoeydonck withdrew the sale offer. [69]

Mission insignia[edit]

Apollo 15 space-flown silver Robbins medallion

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 Hadley Rille. 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 after NASA insisted that the mission number be displayed in Arabic numerals.[70]

Visibility from space[edit]

Plaque left on the descent stage of Falcon

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.[71]

Multimedia[edit]

See also[edit]

Notes[edit]

  1. ^ Mattingly was replaced before launch by Jack Swigert.
  2. ^ The Plain was a shoutout to Scott's alma mater, West Point, as that is the name of the parade ground there.[ALSJ 2]

References[edit]

 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.

  1. ^ Orloff, Richard W. (September 2004) [First published 2000]. "Table of Contents". Apollo by the Numbers: A Statistical Reference. NASA History Division, Office of Policy and Plans. NASA History Series. Washington, D.C.: NASA. ISBN 0-16-050631-X. LCCN 00061677. NASA SP-2000-4029. Archived from the original on August 23, 2007. Retrieved July 18, 2009.
  2. ^ a b c d Orloff & Harland, p. 426.
  3. ^ "NASA NSSDC Master Catalog – Apollo 15 LM descent stage". Retrieved 2011-01-01.
  4. ^ Chaikin, pp. 232–233.
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  12. ^ Orloff & Harland, pp. 279, 327, 393–394, 426.
  13. ^ Chaikin, pp. 387–396.
  14. ^ Chaikin, pp. 397–402.
  15. ^ Reynolds, p. 171.
  16. ^ Lindsay, p. 303.
  17. ^ Scott & Leonov, 4490–4513.
  18. ^ Compton, p. 236.
  19. ^ Chaikin, pp. 402–403.
  20. ^ Scott & Leonov, 4521–4529.
  21. ^ Reynolds, p. 172.
  22. ^ Harland, p. 80.
  23. ^ Scott & Leonov, 4412.
  24. ^ Worden, 2373–2408.
  25. ^ Scott & Leonov, 4571–4579.
  26. ^ Orloff & Harland, p. 430.
  27. ^ Mission Report, p. 1.
  28. ^ a b c d Woods, W. David (1998). "Apollo 15 Summary". NASA. Retrieved December 15, 2018.
  29. ^ a b Orloff & Harland, p. 431.
  30. ^ a b Orloff & Harland, p. 435.
  31. ^ a b c Orloff & Harland, p. 432.
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  35. ^ Chaikin, pp. 414–415.
  36. ^ Scott & Leonov, 4865–4869.
  37. ^ Beattie, p. 231.
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  39. ^ Chaikin, p. 415.
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  47. ^ Harland, p. 115.
  48. ^ Pearlman, Robert Z. "'Moon Mail' and Space Stamps Now on Display in World's Largest Postal Gallery". SPACE.com. Retrieved December 21, 2018.
  49. ^ a b c Compton, online chapter To the Mountains of the Moon
  50. ^ a b "Apollo 15 Command and Service Module (CSM)". NASA. Retrieved December 21, 2018.
  51. ^ Lindsay, pp. 301–302.
  52. ^ "Location of Apollo Lunar Modules". Smithsonian Air and Space Museum. Retrieved September 9, 2018.
  53. ^ Compton, online chapter The Lunar Rover and New Experiments
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  58. ^ Bell, Trudy E. (November 6, 2006). Phillips, Tony, ed. "Bizarre Lunar Orbits". Science@NASA. NASA. Retrieved December 9, 2012. Lunar mascons make most low lunar orbits unstable ... As a satellite passes 50 or 60 miles overhead, the mascons pull it forward, back, left, right, or down, the exact direction and magnitude of the tugging depends on the satellite's trajectory. Absent any periodic boosts from onboard rockets to correct the orbit, most satellites released into low lunar orbits (under about 60 miles or 100 km) will eventually crash into the Moon. ... [There are] a number of 'frozen orbits' where a spacecraft can stay in a low lunar orbit indefinitely. They occur at four inclinations: 27°, 50°, 76°, and 86°"—the last one being nearly over the lunar poles. The orbit of the relatively long-lived Apollo 15 subsatellite PFS-1 had an inclination of 28°, which turned out to be close to the inclination of one of the frozen orbits—but poor PFS-2 was cursed with an inclination of only 11°.
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  69. ^ Van den Bussche 1980, pp. 16–17
  70. ^ Worden & French 2011, pp. 144–145
  71. ^ "The 'halo' area around Apollo 15 landing site observed by Terrain Camera on SELENE(KAGUYA)" (Press release). Chōfu, Tokyo: Japan Aerospace Exploration Agency. May 20, 2008. Retrieved December 26, 2018.

Apollo Lunar Flight Journal[edit]

  1. ^ a b c Woods, W. David; O'Brien, Frank. "Day 11: Worden's EVA Day". Apollo 15 Flight Journal. NASA. Archived from the original on June 29, 2011. Retrieved December 26, 2018.
  2. ^ a b c d e Woods, W. David; O'Brien, Frank, eds. (1998). "Leaking Tunnel and Jettison of the LM". Apollo 15 Flight Journal. NASA. Retrieved December 16, 2018.
  3. ^ a b Woods, W. David; O'Brien, Frank, eds. (1998). "Day 5: Waking in the Descent Orbit". Apollo 15 Flight Journal. NASA. Retrieved September 6, 2018.
  4. ^ a b Woods, W. David; O'Brien, Frank, eds. (1998). "Launch and Reaching Earth Orbit". Apollo 15 Flight Journal. NASA. Retrieved September 5, 2018.
  5. ^ Woods, W. David; O'Brien, Frank, eds. (1998). "Earth Orbit and Translunar Injection". Apollo 15 Flight Journal. NASA. Retrieved September 5, 2018.
  6. ^ Woods, W. David; O'Brien, Frank, eds. (1998). "Transposition, Docking and Extraction". Apollo 15 Flight Journal. NASA. Retrieved September 5, 2018.
  7. ^ Woods, W. David; O'Brien, Frank, eds. (1998). "Day 2: Checking the SPS". Apollo 15 Flight Journal. NASA. Retrieved September 5, 2018.
  8. ^ a b Woods, W. David; O'Brien, Frank, eds. (1998). "Day 2: Entering the LM". Apollo 15 Flight Journal. NASA. Retrieved September 5, 2018.
  9. ^ Woods, W. David; O'Brien, Frank, eds. (1998). "Day 3: Leaking Water and the Top of the Hill". Apollo 15 Flight Journal. NASA. Retrieved September 5, 2018.
  10. ^ Woods, W. David; O'Brien, Frank, eds. (1998). "Day 4: Lunar Encounter". Apollo 15 Flight Journal. NASA. Retrieved September 5, 2018.
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  14. ^ Woods, W. David; O'Brien, Frank, eds. (1998). "Solo Orbital Operations-2". Apollo 15 Flight Journal. NASA. Retrieved December 16, 2018.
  15. ^ Woods, W. David; O'Brien, Frank, eds. (1998). "Solo Orbital Operations-4". Apollo 15 Flight Journal. NASA. Retrieved December 16, 2018.

Apollo Lunar Surface Journal[edit]

  1. ^ Jones, Eric M., ed. (1995). "Sampling at Head Crater and Bench Crater". Apollo 12 Lunar Surface Journal. NASA. Retrieved September 4, 2018.
  2. ^ a b c d e f g Jones, Eric M., ed. (1996). "Landing at Hadley". Apollo 15 Lunar Surface Journal. NASA. Retrieved July 14, 2011.
  3. ^ Jones, Eric M., ed. (1996). "Deploying the Lunar Roving Vehicle". Apollo 15 Lunar Surface Journal. NASA. Retrieved September 13, 2018.
  4. ^ Jones, Eric M., ed. (1996). "Stand-Up EVA". Apollo 15 Lunar Surface Journal. NASA. Retrieved July 14, 2011.
  5. ^ Jones, Eric M., ed. (1996). "Wake-up for EVA-1". Apollo 15 Lunar Surface Journal. NASA. Retrieved September 9, 2018.
  6. ^ Jones, Eric M., ed. (1996). "Preparations for EVA-1". Apollo 15 Lunar Surface Journal. NASA. Retrieved September 13, 2018.
  7. ^ Jones, Eric M., ed. (1996). "Driving to Elbow Crater". Apollo 15 Lunar Surface Journal. NASA. Retrieved September 16, 2018.
  8. ^ a b c d e f g Jones, Eric M. (1995). "Mountains of the Moon". Apollo 15 Lunar Surface Journal. NASA. Retrieved December 21, 2018.
  9. ^ a b c Jones, Eric M., ed. (1996). "The Hammer and the Feather". Apollo 15 Lunar Surface Journal. NASA. Retrieved December 21, 2018.
  10. ^ Jones, Eric M., ed. (1996). "Stand-Up EVA". Apollo 15 Lunar Surface Journal. NASA. Retrieved September 9, 2018.

Bibliography[edit]

External links[edit]

NASA reports

Multimedia