Apollo 15 descends to the Pacific Ocean with two functional parachutes. (NASA)
7 August 1971: At 6:45 a.m., local time, 287 nautical miles (531 kilometers) north of Honolulu, Hawaii, the Apollo 15 command module Endeavour “splashed down” after twelve days in space. On board were Colonel David Randolph Scott, Mission Commander; Major Alfred Merrill Worden, Command Module Pilot; and Lieutenant Colonel James Benson Irwin, Lunar Module Pilot. All three were United States Air Force officers and NASA astronauts.
During the descent following reentry, one of the three main parachutes fouled. This did not cause any problems, though, as only two were necessary.
The spacecraft landed approximately 5.3 nautical miles (9.8 kilometers) from the primary recovery ship, the amphibious assault ship USS Okinawa (LPH-3).
The Apollo 15 flight crew disembarks the Sikorsky SH-3G recovery helicopter (Bu. No. 149930) aboard USS Okinawa (LPH-3), 21:25 UTC, 7 August 1971. Left to right, Scott, Worden, Irwin. (NASA)
Apollo 15 was the ninth manned mission of the Apollo Program, and the fourth to land on The Moon. The total duration of the flight was 12 days, 7 hours, 11 minutes, 53.0 seconds.
This was the first mission that the crew were not quarantined after returning to Earth.
The Apollo 15 command module is displayed at the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio.
Apollo 15 command module (CSM-112) at the National Museum of the United States Air Force. (U.S. Air Force)
Apollo 15: Jim Irwin loads the LRV for EVA-1, 31 July 1971. The mountain behind the Lunar Module is Hadley Delta. (David Scott/NASA)
At 13:52:31 UTC, 31 July 1971, (T + 120:18:31) the Lunar Roving Vehicle was deployed from Apollo 15’s Lunar Module, Falcon. This was the first time that an LRV had been used on the surface of the moon.
The LRV was a four-wheeled, electrically-powered, surface transportation vehicle designed to carry two astronauts and their equipment to explore areas farther away from the landing site than they would be able to by walking.
The LRV was built by Boeing at Kent, Washington. prime contractor. The wheels, electric motors and suspension system were built by a General Motors subsidiary in Santa Barbara, California.
Three-view drawing of Lunar Roving Vehicle with dimensions (Lunar Roving Vehicle Operations Handbook LS006-002-2H, Page 1 – 3, Fig. 1 – 1, The Boeing Company LRV Systems Engineering, Huntsville, AL)
The lunar rover was constructed of welded aluminum tubing and hinged to allow folding to store aboard the lunar module. It had two folding seats for the astonauts. The four tires were ingeniously constructed of woven steel strands (0.083 cm). about 122 inches (3.10 meters) long. The wheelbase was 90 inches (2.29 meters) and the track was 72 inches (1.83 meters). It was 44.8 inches (1.14 meters) high.
Jim Irwin with LRV at Hadley Rille, 31 July 1971. (Dave Scott/NASA)Jim Irwin with LRV at Hadley Rille, 30 July 1972. Detail from image above. (Dave Scott/NASA)
The mass of the empty LRV was 210 kilograms (463 pounds on Earth, but only about 77 pounds on the surface of the Moon), and it was capable of transporting a payload of 490 kilograms (about 81 “moon-pounds”).
The four tires were ingeniously constructed of woven steel strands (0.083 centimeters diameter). The tire was 81.8 centimeters (32.2 inches) in diameter, and 23 centimeters (9.1 inches) wide. The aluminum wheels were 80 centimeters (31.5 inches) in diameter and 24 centimeters (9.4 inches) wide. The tires’ traction was enhanced by “chevrons” made of titanium.
Lunar Roving Vehicle wheel and tire assembly. (NASM-A197508300000_PS02)
Each wheel was driven by a DC electric motor, capable of 0.25 horsepower at 10,000 r.p.m. There was a 80:1 speed reduction.
Electric power for the vehicle was provided by two 36-volt (+5/-3 volts) silver-zinc potassium hydroxide batteries with a total capacity of 121 amperes/hour. The batteries were not rechargeable.
The Apollo 15 landing crew made three excursions with the LRV, traveling a total distance of 27.8 kilometers (17.3 statute miles) in 3 hours, 26 minutes driving time. The maximum speed reached was 12 km/h (7.5 mph). NASA reported that “the longest single traverse was 12.5 km [7.8 miles] and the maximum range from the LM was 5.0 km. [3.1 miles]“
Apollo 15’s three LRV traverses. Image from the Lunar Reconnaissance Orbiter. (NASA/GSFC/Arizona State University)
Apollo 15 (AS-510) lifts off from Launch Complex 39A, Kennedy Space Center, Cape Canaveral, Florida, at 13:34:00.6 UTC, 26 July 1971. (NASA)
26 July 1971: At 9:34:00.6 a.m., Eastern Daylight Time (13:34:00.6 UTC), the Apollo 15/Saturn V (AS-510) lifted off from Launch Complex 39A, Kennedy Space Center, Cape Canaveral, Florida. The three-man flight crew were Colonel David Randolph Scott, United States Air Force, Mission Commander, on his third space flight; Major Alfred Merrill Worden, USAF, Command Module Pilot, on his first mission; and Lieutenant Colonel James Benson Irwin, USAF, Lunar Module Pilot, also on his first space mission.
Their destination was was Hadley Rille, Mare Imbrium, The Moon.
The flight crew of Apollo 15, left to right, Colonel David R. Scott, Major Alfred M. Worden and Lieutenant Colonel James B. Irwin. (NASA)
At first stage ignition, the Apollo 15/Saturn V launch vehicle (AS-510) had a total weight of 6,494,415 pounds (2,945,817 kilograms). The five Rocketdyne F-1 engines of the S-IC first stage produced 7,558,000 pounds of thrust (33,619.66 kilonewtons).
After the first stage engines shut down, the S-IC stage was jettisoned. The five Rocketdyne J-2 engines of the S-II second stage received the Engine Start Command at T + 161.95 seconds. They produced 1,169,662 pounds of thrust (5,202.92 kilonewtons), and were themselves shut down at T + 549.06 seconds. The second stage was jettisoned and the single J-2 of the S-IVB third stage started at T + 553.2 and shut down at T + 694.7 seconds. The S-IVB engine produced 202,965 pounds of thrust (902.83 kilonewtons) during its First Burn.
Apollo 15 entered a parking orbit 11 minutes, 44 seconds after launch. The nearly-circular 105.3 × 106.4 miles (169.5 × 171.3 kilometers) orbit had a period of 1 hour, 27.84 minutes.
This 1966 illustration depicts the J-2 engine of the S-IVB third stage firing to send the Apollo spacecraft to the Moon. (NASA)
The Trans Lunar Injection maneuver (TLI) began at mission elapsed time 02:50:03. The total vehicle mass at the S-IVB’s Second Burn ignition was 307,661 pounds (139,552 kilograms). The J-2 engine produced 203,111 pounds of thrust (903.48 kilonewtons. The engine shut down at T + 02:55:53.7.
Endeavour docked with Falcon to extrack from S-IVB adapter fairing. (NASA)
Once on the way to The Moon, the Command and Service Module Endeavour separated from the S-IVB third stage, reversed its relative position and then extracted the Lunar Module Falcon from the stage adaptor fairing. The S-IVB third stage was then released, continuing its own journey. It impacted the lunar surface at mission elapsed time 79:24:41.55, traveling 5,764 miles per hour (9,277 kilometers per hour).
This was the fifth manned lunar landing mission (though Apollo 13 did not land).
On this flight, NASA was sending a powered wheeled transport vehicle, the Lunar Roving Vehicle, or LRV. This would allow the astronauts on the moon’s surface to travel farther from the landing point, spend less time getting where they were going, and with less physical exertion. They would also be able to return to their space craft with more geologic samples. The emphasis on this flight was to conduct a meaningful scientific examination of the surface. The astronauts had received extensive training in this regard.
