NASA's Apollo 15 mission -- which launched from Cape Canaveral on July 26, 1971 -- was the fourth American space mission to land men on the moon. Here, on the 40th anniversary of one of the Apollo program's great successes, we celebrate the often-overlooked historic voyage; the astronauts who made it happen; and the mission's lasting impact on NASA and on human space travel.
Astronaut James Irwin -- shown here saluting the American flag during a moon walk in August, 1971 -- spent a total of 66 hours and 54 minutes in space for the Apollo 15 mission. Irwin and Scott are credited with retrieving the famous Genesis rock -- which geologists aged at 4.5 billion years -- during one excursion on the lunar surface.
Apollo 15 launched on July 26, 1971, at 9:34 AM EDT from the Kennedy Space Center at Cape Canaveral, Florida.
Astronaut David Scott -- shown here displaying his photography skills while exploring the moon's mountainous Hadley Delta region -- shared this lunar-inspired sentiment in National Geographic magazine in 1973: "When I look at the moon I do not see a hostile, empty world. I see the radiant body where man has taken his first steps into a frontier that will never end."
As he stepped on the moon for the first time, Scott -- shown here drilling a hole in the surface for heat sensors -- made this observation: "There's a fundamental truth to our nature, man must explore, and this is exploration at its greatest."
Irwin tends to the lunar roving vehicle. Mount Hadley -- named for 18-century English mathematician John Hadley, the inventor of the navigational device, the octant -- can be seen in the distance.
As its parachutes trail high above -- one of the three had failed to deploy correctly, but only two were needed for a safe landing -- the Apollo 15 capsule with Scott, Irwin, and Worden aboard splashes down in the Pacific Ocean.
The mission marked the longest sustained period of time that humans had spent on the moon's surface -- three full days, 18 hours of which were spent in activities outside the lunar lander -- and pointed the way toward even lengthier and bolder excursions into space in the years and decades to come. See more great pictures of Apollo 15 at LIFE.com.
Apollo 15 was the fourth American space mission to land men on the moon. On the historic 40th anniversary, we celebrate the often-overlooked voyage. See the full slideshow at LIFE.com.