RocketSTEM Issue #12 - July 2015 | Page 25

Apollo 15 astronaut Dave Scott and the Lunar Rover with a view up Hadley Rille in the background. Credit: NASA via Retro Space Images countdown entered its final seconds, the glare of the Sun was so intense that Scott had to shield his eyes, just to read the instrument panel in front of him. Precisely on time, at 9:34 a.m. EDT, the five F-1 engines of the Saturn V’s first stage came to life with a muffled roar. “You just hang there,” Irwin wrote. “Then you sense a little motion, a little vibration and you start to move. Once you realise you are moving, there is a complete release of tensions. Slowly, slowly, then faster and faster; you feel all that power underneath you.” Four days later, after crossing the vast, 240,000-mile (370,000 km) cislunar gulf, Apollo 15 slipped into orbit around the Moon. Scott and Irwin, aboard the lunar module Falcon, undocked from Worden, in the command module Endeavour, and began their descent towards the surface. Moving in a sweeping arc towards the Apennines, at an altitude of 4 miles (6.4 km), Scott began to discern the long, meandering channel of Hadley Rille. The terrain was less sharply defined than he had anticipated on the basis of simulations, yet he was able to find four familiar craters: Matthew, Mark, Luke and Index—the latter of which they had used in landmark sightings from orbit. (The name “Index” was deliberately chosen instead of “John” in order to stave off complaints from the notorious atheist Madalyn Murray O’Hair, whose criticism of overtly religious symbolic gestures on missions had scalded NASA during the December 1968 mission of Apollo 8.) Dropping through a gap in the lunar mountains, Scott suddenly had the surreal feeling that he was “floating” with strange slowness towards his landing site. “No amount of simulation training,” he wrote in his memoir, Two Sides of the Moon, “had been able to replicate the to both their left and right as they threaded their way towards Hadley. “It made us feel,” he added, “almost as if we should pull our feet up to prevent scraping them along the top of the range.” As they continued to descend, Falcon’s computer transitioned to the so-called “Program 66”, enabling Scott to fly manually. “Dave didn’t want me looking at the surface at all,” Irwin wrote. “He wanted me to concentrate on the information on the computer and other instruments. He wanted to be certain that he had instant informa- “No amount of simulation training had been able to replicate the view we saw out of our windows as we passed by the steep slopes of the majestic lunar Apennine Mountains.” view we saw out of our windows as we passed by the steep slopes of the majestic lunar Apennine Mountains.” In the simulator, they “flew” a television camera towards a small, relatively flat patch of plaster-of-Paris; now, doing it for real, they drifted between the astonishing 16,400-foot (5,000-meter) peaks of the mountains tion relayed to him. He was going to pick out the landmarks. But Dave couldn’t identify the landmarks; the features on the real surface didn’t look like the ones we had trained with.” Scott could see Hadley Rille, though, and used that long gouge as his marker, but was worried that 23 www.RocketSTEM .org 23