Apollo 15 lunar surface exploration, August 1971. Surveying at Station 7, near Spur Crater, during the Apollo 15 second lunar surface extravehicular activity (EVA-2). Boot prints are at lower right. At upper right is a gnomon, a device used to provide scale and timings for the pictures. At upper centre, the small rock on top of the larger gray fragment is the 'Genesis' rock (sample number 15415), a sample of anorthosite a type of igneous rock. Apollo 15 was the fourth manned mission to land on the Moon. Astronauts David Scott and James Irwin spent a total of 18.5 hours outside their spacecraft, carrying out three exploration trips (EVAs) with the Lunar Roving Vehicle. Photographed by Scott on 1 August 1971.