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Weighing about 85,000 Ibs., the moon bound spacecraft will have three parts: the command module, housing the three-man crew; the service module, with supplies, engines and propellants; and the small landing bug. During the three-day voyage to the moon, the astronauts will make computations and burn fuel to correct their course. They will also take the bug out of the rear of the service module and attach it to the nose of the command module. After arriving in the vicinity of the moon, they will burn a little more fuel to nudge their ship into a 100-mile-high lunar orbit. Then two of the crewmen will crawl into the bug through an airlock and detach it.
The bug will have its own rocket engines. By firing those engines briefly, the crew will be able to put their ship into an elliptical orbit that will dip to within ten miles of the moon's airless surface. As they swoop through perigee, the men in the bug will study the barren geography below, trying to recognize places that they have seen on maps and photographs. They will be able to correct their orbit as they climb back to apogee.
If anything has gone wrong, they will still have a chance to rejoin the mother ship and return to earth without landing. But if all is well, they will make their landing attempt on their next close approach to the moon. By burning sufficient fuel, they will check the motion of their bug, making it sink slowly toward the surface. They will be able to hover for about one minute and move sideways 1,000 ft. in search of a good landing place. Finally the bug will settle down, steadying itself on four spidery legs.
Later crews may spend as many as four days exploring the moon, but the first men to land will probably take off again promptly. They will wait only for the mother ship to appear overhead. When it is about 3° behind their zenith, they will fire their rockets and rise vertically, leaving their landing gear behind. Because of low lunar gravity (16% of the earth's) and lack of atmosphere, take-off from the moon should be comparatively easy. NASA planners believe that finding the mother ship and joining it will be no more difficult than long-practiced rendezvous with the same equipment while on earth orbit. The bug will be abandoned, to circle endlessly around the moon, and the reunited three-man crew will head back for earth. They will have to graze the atmosphere, hitting a "corridor" only 40 miles deep, but they will have plenty of time to correct their course.
As they explain these maneuvers, NASA enthusiasts make the trip sound as simple as a Sunday picnic, but no one actually believes that the voyage will be safe or easy. All sorts of unexpected obstacles may force changes of plan. No one knows, for instance, whether human bodies can stand a full week exposed to zero gravity. If they cannot, some sort of substitute gravity will have to be supplied by spinning the spacecraft−a stunt that will call for radically new apparatus. Another unknown is the lunar surface; no one is sure at present just how hostile it is. Astronomers point out that it is inconceivably old, that it has stewed in a vacuum and been exposed to fierce radiation for billions of years. It may be spotted with strange things, such as free radicals−highly