Apollo 15 was the first in a series of missions designed to conduct exploration of the moon over longer periods, greater ranges, and with more instruments for scientific data acquisition than on previous missions. Major modifications and augmentations to the basic Apollo hardware were made, the most significant being installation of a scientific instrument module in one of the service module bays, modification of the lunar module to carry a greater scientific payload and permit a longer stay on the lunar surface, and the provision of a lunar roving vehicle. The landing site chosen for the mission was an area near the foot of the Apennine Mountains and adjacent to Hadley Rille. The mission accomplished all of its objectives and is providing the scientific community with a large amount of new information concerning the moon and its characteristics.

The space vehicle was launched from the Kennedy Space Center, Complex 39A at 9:34:00.6 a.m. e.d.t. (13:34:00.6 G.M.T.), on July 26, 1971. The spacecraft was manned by Colonel David R. Scott, Commander; Major Alfred J. Worden, Command Module Pilot; and Lt. Col. James B. Irwin, Lunar Module Pilot. The spacecraft /S-IVB combination was inserted into a nominal Earth parking orbit approximately 1-1 minutes 44 seconds after lift-off. S- IVB restart for translunar injection was initiated during the second revolution at about 2 hours and 50 minutes. The maneuver placed the spacecraft /S-IVB combination on a translunar trajectory that would allow return to an acceptable Earth-entry corridor using the reaction control system engines. Approximately 27 minutes after injection into the translunar trajectory, the command and service module was separated from the S-IVB and docked with the lunar module. The lunar module was extracted from the spacecraft/launch vehicle adapter. Shortly thereafter, the S- IVB tanks were vented and the auxiliary propulsion system was fired to target the S-IVB for a lunar impact. The first spacecraft midcourse correction was performed at about 28 hours 40 minutes with a velocity change of 5.3 ft/sec. One other small midcourse correction was performed during translunar flight.

The spacecraft was inserted into a lunar orbit of 170.1 by 57.7 miles at approximately 78 hours 32 minutes. About 1 hour later, the impact of the S-IVB stage was sensed by the Apollo 12 and 14 seismometers. The impact point was about 146 kilometers (79 miles) from the planned point and useful scientific data were obtained. The spacecraft was inserted into a 58.5-by-9.6 mile orbit at about 82 hours 40 minutes and a trim maneuver was performed later to adjust the perilune for powered descent. Undocking and separation occurred at about 100 hours 39 minutes and, approximately 1 hour later, the command and service module was placed in a near-circular orbit in preparation for the acquisition of scientific data.

The lunar module touched down on the lunar surface about 550 meters (1800 feet) from the planned target point at 104:42:29. The landing point was 26 degrees 6 minutes 4 seconds north latitude and 3 degrees 39 minutes 10 seconds east longitude (referenced to the Rima Hadley Lunar Photomap, Orbiter V site 26.1, First Edition, published by the U.S. Army Topographic Command, April 1970). A hover time capability of about 103 seconds remained after touchdown.

About 2 hours after landing, the Commander stood on the ascent engine cover with the upper part of his body extending through the upper hatch opening to photograph and describe the area surrounding the landing site. This extravehicular activity period lasted about 33 minutes. Approximately 12 1/2 hours later, the first lunar surface extravehicular activity commenced. Initially, the crew collected and stowed a contingency sample, deployed the lunar roving vehicle, unstowed the Apollo lunar surface experiments package and other equipment, and configured the lunar roving vehicle for lunar surface operations. Some problems were experienced in deploying and checking out the rover, but these were worked out and the crew drove the vehicle to Elbow Crater where they collected and documented samples, giving an enthusiastic and informative commentary on lunar features. Television control during various stops was provided by the Mission Control Center. After obtaining additional samples and photographs near St. George Crater, the crew returned to the lunar module using the lunar rover navigation system. The distance driven was about 10.3 kilometers (5.6 miles). The crew then proceeded to the selected Apollo lunar surface experiments package deployment site, approximately 110 meters (360 feet) west-northwest of the lunar module. They deployed the experiments essentially as planned except that the second heat flow experiment probe was not emplaced because drilling was more difficult than expected and the hole was not completed. The first extravehicular activity lasted about 6 hours and 33 minutes.

The crew spent about 16 hours in the cabin between the first and second extravehicular periods. Upon egress for the second extravehicular activity, the lunar rover was checked out and prepared for the second sortie. The first leg of the 12.5-kilometer (6.8-mile) round trip was south to the Apennine front, but east of the first traverse. Stops were made at Spur Crater and other points along the base of the front, as well as Dune Crater on the return trip. The return route closely followed the outbound route. Documented samples, a core sample, and a comprehensive sample were collected, and photographs were taken. After reaching the lunar module, the crew returned to the experiments package site where the Commander completed drilling the second hole for the heat flow experiment and emplaced the probe. During this period, the Lunar Module Pilot performed soil mechanics tasks. Drilling was again performed by the Commander to obtain a deep core sample, but the operation was terminated because of time constraints. The crew then returned to the lunar module and deployed the United States flag. The second extravehicular activity ended after about 7 hours 12 minutes.

The crew spent almost 14 hours in the cabin following the second extravehicular period. The third extravehicular activity began later than originally planned to allow additional time for crew rest. This and other delays at the experiments package site required deleting the planned trip to the North Complex. The first stop was at the experiments package site to retrieve the deep core sample. Two core sections were disengaged, but the drill and the remaining four sections could not be separated and were left for later retrieval. The third geological traverse was in a westerly direction and included stops at Scarp Crater, Rim Crater, and The Terrace, an area along the rim of Hadley Rille. Extensive samples were obtained as well as a double core tube and photographs of the west wall of Hadley Rille where exposed layering was observed. The return trip was east toward the lunar module with a stop at the experiments package site to retrieve the remaining sections of the deep core sample. One more section was separated and the remaining three sections were returned in one piece. After returning to the lunar module, the lunar rover was unloaded and parked for ground-controlled television coverage of the lunar module ascent. The total distance traveled during the third extravehicular activity was about 5.1 kilometers (2.8 miles), and it lasted about 4 hours 50 minutes. The total distance traveled with the lunar roving vehicle during the three extravehicular periods was 27.9 kilometers (15.1 miles) and the total weight of lunar samples collected was about 170 pounds.

While the lunar module was on the surface, the Command Module Pilot completed 34 lunar orbits operating scientific instrument module experiments and cameras to obtain data concerning the lunar surface and the lunar environment. Some of the scientific tasks accomplished during this time were the photographing of the sunlit lunar surface; gathering data needed for mapping the bulk chemical composition of the lunar surface and determining the geometry of the moon along the ground track; visually surveying regions of the moon to assist in identification of processes which formed geologic features; obtaining lunar atmospheric data; and surveying gamma-ray and X-ray sources. Good-resolution panoramic and mapping camera photographs were obtained during the mission.

After 66 hours 54 minutes and 53 seconds on the lunar surface, the ascent stage lifted off at 171:37:23. A nominal lunar-module-active rendezvous was performed followed by docking at about 173 hours 36 minutes.

The lunar module was jettisoned one revolution later than planned because of some difficulty with verifying the tunnel sealing and suit integrity. Jettisoning occurred at about 179 hours 30 minutes and, about 1 1/2 hours later, the lunar module was deorbited with lunar impact occurring at 26 degrees 21 minutes north latitude and 0 degrees 15 minutes east longitude, about 23 1/2 kilometers (12.7 miles) from the planned impact point and about 93 kilometers (50 miles) west of the Apollo 15 landing site. The impact was recorded by the Apollo 12, 14, and 15 seismic stations.

Before leaving lunar orbit, a subsatellite was deployed in an orbit of approximately 76 by 55 miles, and all systems are operating as expected. The transearth injection maneuver was initiated at about 223 hours 49 minutes.

At about 242 hours, transearth coast extravehicular activity began. Television coverage was provided while the Command Module Pilot retrieved film cassettes and examined the scientific instrument module for abnormalities. This extravehicular activity lasted approximately 38 minutes. The-total extravehicular time during the mission was 19 hours and 47 minutes.

A small midcourse correction of 5.6 ft/sec was performed at the seventh midcourse correction opportunity. The command module was separated from the service module as planned and a nominal entry followed with the spacecraft being observed on the main parachutes. During the descent, one of the three main parachutes failed, but a safe landing was made at 295:11:53. The best estimate of the landing coordinates is 26 degrees 7 minutes 48 seconds north latitude and 158 degrees 8 minutes 24 seconds west longitude, about 1 mile from the planned landing point. The crew was brought onboard the recovery ship by helicopter about 39 minutes after landing. The Apollo 15 mission was successfully concluded with the placing of the command module onboard the recovery ship about 1 1/2 hours after landing.