[Illustration: 13. Three inflated bags repositioned the spacecraft following splashdown. The astronauts watch pararescue-man shut hatch during recovery.] “That’s one small step for a man, one giant leap for mankind,” Neil A. Armstrong radioed Houston from Tranquility Base on the Moon. The first footprint had been left on the lunar surface. It was 10:56 P.M. (EDT) on July 20, 1969. Neil Armstrong was Apollo 11’s commander, Michael Collins was command-module pilot, and Edwin “Buzz” Aldrin was the lunar-module pilot. Their journey began at 9:30 A.M. (EDT) when their Saturn 5 lifted off under 3.4 million kilograms (7.5 million pounds) of thrust. The three-man crew made the 383,000-kilometer (238,000-mile) journey to the Moon in three days, traveling in command-module _Columbia_. At 1:46 P.M. (EDT), on July 20, Armstrong and Aldrin separated the lunar module from the _Columbia_ and began the descent to the lunar plain. During the 2 hours and 47 minutes that the astronauts were out on the surface of the Moon, they collected samples, deployed instruments, took photographs, and explored Tranquility Base around the lunar module. After completing their tasks on the Moon, the astronauts rendezvoused with Collins in the command module. Jettisoning the ascent stage, they began the three-day journey back to Earth. Splashdown occurred in the central Pacific Ocean on July 24. The astronauts climbed out of this command module and were recovered by helicopters that took them to the carrier U.S.S. _Hornet_. Prime contractor for Apollo 11’s command module was North American Rockwell Corporation. The _Columbia_ is from the National Aeronautics and Space Administration. [Illustration: 14. View of the Apollo 11 Command Module with Astronaut Collins aboard as seen from the Lunar Module. Terrain in background is the far side of the Moon.] Ponnamperuma Experiments [Illustration: 15. Equipment for Ponnamperuma Experiments.] These experimental devices were constructed by Cyril Ponnamperuma and his colleagues to show that various forms of energy may be used to produce organic molecules of the type found in living organisms. In one experiment, electron beams were fired through a glass tube which contained a mixture of gases believed to resemble the atmosphere of primitive Earth. A number of organic molecules, including amino acids, the “building blocks” of life, were formed as a result. In another experiment—the apparatus on display—electric spark discharges were used to add energy to a mixture of gases and water vapor contained in the device’s upper sphere. The lower sphere contained a solution of water and salts, a solution believed to resemble the slightly salty water of ancient seas. When heat and sparks were added to the gases and salty water, a number of complex organic molecules formed.