Launch Date: 1971-07-26
Launch Vehicle: Saturn 5
Launch Site: Cape Canaveral, United States
Mass: 30371.0 kg


David R. Scott (3) - Commander
Alfred M. Worden (1) - Command Module Pilot
James B. Irwin (1) - Lunar Module Pilot

Number in parentheses indicates number of spaceflights by each individual prior to and including this mission.

Apollo 15 Crew


Apollo 15 was the fourth mission in which humans walked on the lunar surface and returned to Earth. On 30 July 1971 two astronauts (Apollo 15 Commander David R. Scott and LM pilot James B. Irwin) landed in the Hadley Rille/Apennines region of the Moon in the Lunar Module (LM) while the Command and Service Module (CSM) (with CM pilot Alfred M. Worden) continued in lunar orbit. During their stay on the Moon, the astronauts set up scientific experiments, took photographs, and collected lunar samples. The LM took off from the Moon on 2 August and the astronauts returned to Earth on 7 August.

Mission Profile
Apollo 15 launched on 26 July 1971 at 13:34:00 UT (9:34:00 a.m. EDT) on Saturn V SA-510 from Pad 39A at Kennedy Space Center. The spacecraft was inserted into Earth orbit at 13:45:44 UT and translunar injection took place at 16:30:03 UT. The CSM separated from the S-IVB stage at 16:56:24 UT and docked with the LM at 17:07:49 UT. The S-IVB stage was released and burns at 19:22 UT and 23:34 UT sent the stage into a lunar impact trajectory. (It impacted the lunar surface on 29 July at 20:58:42.9 UT at 1.51 S, 11.81 W with a velocity of 2.58 km/s at a 62 degree angle from the horizontal.) A short was discovered in the service propulsion system and contingency procedures were developed for using the engine. A mid-course correction was performed on 27 July at 18:14:22 UT and another on 29 July at 15:05:15. During cruise it was discovered that the LM range/range-rate exterior glass cover had broken and a small water leak had developed in the CM requiring repair and clean-up. The SIM door was jettisoned at 15:40 UT and lunar orbit insertion took place at 20:05:47 UT. The descent orbit maneuver was executed at 00:13:49 UT on 30 July.

Apollo 15 Diagram

Scott and Irwin entered the LM and the LM-CSM undocking maneuver was initiated at 17:48 UT but undocking did not take place. Worden found a loose umbilical plug and reconnected it, allowing the LM to separate from the CSM at 18:13:30 UT. The LM fired its descent engine at 22:04:09 UT and landed at 22:16:29 UT on 30 July 1971 in the Mare Imbrium region at the foot of the Apennine mountain range at 26.1 N, 3.6 E. Scott and Irwin made three moonwalk EVAs totaling 18 hours, 35 minutes. During this time they covered 27.9 km, collected 77.31 kg of rock and soil samples, took photographs, and set up the ALSEP and performed other scientific experiments. This was the first mission which employed the
Lunar Roving Vehicle which was used to explore regions within 5 km of the LM landing site. After the final EVA Scott performed a televised demonstration of a hammer and feather falling at the same rate in the lunar vacuum. The CSM remained in a slightly elliptical orbit from which Worden performed scientific experiments.


Commander Scott taking an intensive course in Geology.

For the first time, geologists had a major voice in lunar exploration. Up until Apollo 15, the emphasis had been on engineering -- creating a reliable vehicle to carry Astronauts back and forth to the Moon. It was becoming clear though, that the program was going to be cut, and where mission planners thought they had time to develop a scientific program, this was reduced to only having three missions (15, 16 and 17). All of the remaining Astronauts were put through severe training to learn (I don't want to say a crash course), in geology.

The LM lifted off from the Moon at 17:11:22 UT on 2 August after 66 hours, 55 minutes on the lunar surface. After the LM docked with the CSM at 19:09:47 UT the lunar samples and other equipment were transferred from the LM. The LM was jettisoned at 01:04:14 UT on 3 August, after a one orbit delay to ensure LM and CSM hatches were completely sealed. The LM impacted the Moon on 3 August 03:03:37.0 UT at 26.36 N, 0.25 E, 93 km west of the Apollo 15 ALSEP site, with an estimated impact velocity of 1.7 km/s at an angle of ~3.2 degrees from horizontal. Experiments were performed from orbit over the next day. After Apollo 15 underwent an orbit-shaping maneuver the scientific subsatellite was spring-launched from the SM SIM bay at 20:13:19 UT on 4 August into a 102.0 x 141.3 km lunar orbit. Transearth injection began on the next orbit with a 2 minute, 21 second main engine burn at 21:22:45 UT. On 5 August, Worden carried out the first deep space EVA when he exited the CM and made three trips to the SIM bay at the rear of the SM to retrieve film cannisters and check the equipment. Total EVA time was 38 minutes, 12 seconds. The CM separated from the SM at 20:18:00 UT on 7 August. During descent, one of the three main parachutes failed to open fully, resulting in a descent velocity of 35 km/hr (21.8 mph), 4.5 km/hr (2.8 mph) faster than planned. Apollo 15 splashed down in the Pacific Ocean on 7 August 1971 at 20:45:53 UT (4:45:53 p.m. EDT) after a mission elapsed time of 295 hrs, 11 mins, 53 secs. The splashdown point was 26 deg 7 min N, 158 deg, 8 min W, 330 miles north of Honolulu, Hawaii and 9.8 km (6.1 mi) from the recovery ship USS Okinawa.

Performance of the spacecraft, the first of the Apollo J-series missions, was excellent for most aspects of the mission. The primary mission goals of exploration of the Hadley-Appenine region, deployment of the ALSEP and other scientific experiments, collection of lunar samples, surface photography, and photography and other scientific experiments from orbit, and engineering evaluation of new Apollo equipment, particularly the rover, were achieved. Scott, 39, was an Air Force Colonel on his third spaceflight (he'd flown previously on Gemini 8 and Apollo 9), Worden, 39, was an Air Force major on his first spaceflight, and Irwin, 41, was an Air Force lt. colonel also on his first spaceflight. The backup crew for this mission was Richard Gordon, Vance Brand, and Harrison Schmitt. The Apollo 15 command module "Endeavor" is on display at the USAF Museum at Wright-Patterson Air Force Base, Dayton, Ohio.

Spacecraft and Subsystems
As the name implies, the Command and Service Module (CSM) was comprised of two distinct units: the Command Module (CM), which housed the crew, spacecraft operations systems, and re-entry equipment, and the Service Module (SM) which carried most of the consumables (oxygen, water, helium, fuel cells, and fuel) and the main propulsion system. The total length of the two modules attached was 11.0 meters with a maximum diameter of 3.9 meters. Block II CSM's were used for all the crewed Apollo missions. Apollo 15 was the first of the Apollo J-series spacecraft. The CSM mass of 30,371 kg was the launch mass including propellants and expendables, of this the Command Module (CM-112) had a mass of 5875 kg and the Service Module (SM-112) 24,496 kg.

Telecommunications included voice, television, data, and tracking and ranging subsystems for communications between astronauts, CM, LM, and Earth. Voice contact was provided by an S-band uplink and downlink system. Tracking was done through a unified S-band transponder. A high gain steerable S-band antenna consisting of four 79-cm diameter parabolic dishes was mounted on a folding boom at the aft end of the SM. Two VHF scimitar antennas were also mounted on the SM. There was also a VHF recovery beacon mounted in the CM. The CSM environmental control system regulated cabin atmosphere, pressure, temperature, carbon dioxide, odors, particles, and ventilation and controlled the temperature range of the electronic equipment.

Command Module
The CM was a conical pressure vessel with a maximum diameter of 3.9 m at its base and a height of 3.65 m. It was made of an aluminum honeycomb sandwhich bonded between sheet aluminum alloy. The base of the CM consisted of a heat shield made of brazed stainless steel honeycomb filled with a phenolic epoxy resin as an ablative material and varied in thickness from 1.8 to 6.9 cm. At the tip of the cone was a hatch and docking assembly designed to mate with the lunar module. The CM was divided into three compartments. The forward compartment in the nose of the cone held the three 25.4 m diameter main parachutes, two 5 m drogue parachutes, and pilot mortar chutes for Earth landing. The aft compartment was situated around the base of the CM and contained propellant tanks, reaction control engines, wiring, and plumbing. The crew compartment comprised most of the volume of the CM, approximately 6.17 cubic meters of space. Three astronaut couches were lined up facing forward in the center of the compartment. A large access hatch was situated above the center couch. A short access tunnel led to the docking hatch in the CM nose. The crew compartment held the controls, displays, navigation equipment and other systems used by the astronauts. The CM had five windows: one in the access hatch, one next to each astronaut in the two outer seats, and two forward-facing rendezvous windows. Five silver/zinc-oxide batteries provided power after the CM and SM detached, three for re-entry and after landing and two for vehicle separation and parachute deployment. The CM had twelve 420 N nitrogen tetroxide/hydrazine reaction control thrusters. The CM provided the re-entry capability at the end of the mission after separation from the Service Module.

Service Module
The SM was a cylinder 3.9 meters in diameter and 7.6 m long which was attached to the back of the CM. The outer skin of the SM was formed of 2.5 cm thick aluminum honeycomb panels. The interior was divided by milled aluminum radial beams into six sections around a central cylinder. At the back of the SM mounted in the central cylinder was a gimbal mounted re-startable hypergolic liquid propellant 91,000 N engine and cone shaped engine nozzle. Attitude control was provided by four identical banks of four 450 N reaction control thrusters each spaced 90 degrees apart around the forward part of the SM. The six sections of the SM held three 31-cell hydrogen oxygen fuel cells which provided 28 volts, an auxiliary battery, three cryogenic oxygen and three cryogenic hydrogen tanks, four tanks for the main propulsion engine, two for fuel and two for oxidizer, the subsystems the main propulsion unit, and a Scientific Instrument Module (SIM) bay which held a package of science instruments and cameras to be operated from lunar orbit and a small subsatellite to be put into lunar orbit. Two helium tanks were mounted in the central cylinder. Electrical power system radiators were at the top of the cylinder and environmental control radiator panels spaced around the bottom.