October 18, 1952
HERE is how we shall go to the moon. The pioneer expedition, fifty scientists and technicians, will take off from the space station's orbit in three clumsy-looking but highly efficient rocket ships. They won't be streamlined: all travel will be in space, where there is no air to impede motion. Two will be loaded with propellant for the five-day, 239,000-mile trip and the return journey. The third, which will not return, will carry only enough propellant for a one-way trip; the extra room will be filled with supplies and equipment for the scientists' six-week stay.
On the outward voyage, the rocket ships will hit a top speed of 19,500 miles per hour about thirty-three minutes after departure. Then the motors will be stopped, and the ships will fall the rest of the way to the moon.
Such a trip takes a great deal of planning. For a beginning, we must decide what flight path to follow, how to construct the ships, and where to land. But the project could be completed within the next twenty-five years. There are no problems involved to which we don't have the answers-or the ability to find them-right now.
First, where shall we land? We may have a wide choice, once we have had a close look at the moon. We'll get that look on a preliminary survey flight. A small rocket ship taking off from the space station will take us to within 50 miles of the moon to get pictures of its meteor-pitted surface-including the "back" part, never visible from the earth.
We'll study the photographs for a suitable site. Several considerations limit our selection. Because the moon's surface has 14,600,000 square miles-about one thirteenth that of the earth-we won't be able to explore more than a small area in detail, perhaps part of a section 500 miles in diameter. Our scien tists want to see as many kinds of lunar features as possible, so we'll pick a spot of particular interest to them. We want radio contact with the earth, too; that means we'll have to stick to the moon's "face," for radio waves won't reach across space to any point the eye won't reach. We can't land at the moon's equator because its noonday temperatures reach an unbearable 220° F., more than hot enough to boil water.
We can't land where the surface is too rugged, because we need a flat place to set down. Yet the site can't be too flat, either-grain-sized meteors constantly bombard the moon at speeds of several miles a second; we'll have to set up camp in a crevice where we have protection from these bullets.
There's one section of the moon that meets all our requirements, and unless something better turns up on closer inspection, that's where we'll land. It's an area called Sinus Roris, or "Dewy Bay," on the northern branch of a plain known as Oceanus Procellarum, or "Stormy Ocean" (so called by early astron omers who thought the moon's plains were great seas) . Dr. Fred L. Whipple, chairman of Harvard University's astronomy department, says Sinus Roris is ideal for our purpose-about 650 miles from the lunar north pole, where the daytime temperature averages a reasonably pleasant 40 degrees and the terrain is flat enough to land on, yet irregular enough to hide in. With a satisfactory site located, we start our detailed planning.
To save fuel and time, we want to take the shortest practical course. The moon moves around the earth in an elliptical path once every 27.3 days. The space station, our point of departure, circles the earth once every two hours. Every two weeks, their paths are such that a rocket ship from the space station will intercept the moon in just five days. The best conditions for the return trip will occur two weeks later, and again two weeks after that. With their stay limited to mulitiples of two weeks, our scientists have set themselves a six-week limit for the first exploration of the moon-long enough to accomplish some constructive research, but not long enough to require a prohibitive supply of essentials like liquid oxygen, water, and food. Six months before our scheduled take-off, we begin piling up construction materials, supplies, and equipment at the space station. This operation is a massive, impressive one, involving huge, shuttling, cargo rocket ships, scores of hard-working handlers, and tremendous amounts of equipment. Twice a day, pairs of sleek rocket transports from the earth sweep into the satellite's orbit and swarms of workers unload the 36 tons of cargo each carries. With the arrival of the first shipment of material, work on the first of the three moon going space craft gets under way, picking up intensity as more and more equipment arrives.
The supplies are not stacked inside the space station; they're just left floating in space. They don't have to be secured, and here's why: the satellite is traveling around the earth at 15,840 miles an hour; at that speed, it can't be affected by the earth's gravity, so it doesn't fall, and it never slows down because there's no air resistance. The same applies to any other object brought into the orbit at the same speed: to park beside the space station, a rocket ship merely adjusts its speed to 15,840 miles per hour; and it, too, becomes a satellite. Crates moved out of its hold are traveling at the same speed in relation to the earth, so they also are weightless satellites.
As the weeks pass and the unloading of cargo ships continues, the construction area covers several littered square miles. Tons of equipment lie about- aluminum girders, collapsed nylon-and-plastic fuel tanks, rocket motor units, turbopumps, bundles of thin aluminum plate, a great many nylon bags containing smaller parts. It's a bewildering scene, but not to the moon-ship builders. All construction parts are color-coded with blue-tipped cross braces fitting into blue sockets, red joining members keyed to others of the same color, and so forth. Work proceeds swiftly.
In fact, the workers accomplish wonders, considering the obstacles confronting a man forced to struggle with unwieldy objects in space. The men move clumsily, hampered by bulky pressurized suits equipped with such necessities of space life as air conditioning, oxygen tanks, walkie-talkie radios, and tiny rocket motors for propulsion. The work is laborious, for although objects are weightless they still have inertia. A man who shoves a one-ton girder makes it move all right, but he makes himself move, too. As his inertia is less than the girder's, he shoots backward much farther than he pushes the big piece of metal forward.
The small, personal rocket motors help the workers move some of the construction parts; the big stuff is hitched to space taxis, tiny pressurized rocket vehicles used for short trips outside the space station.
As the framework of the new rocket ships takes form, big, folded nylon-and plastic bundles are pumped full of air; they become spherical, and plastic astro domes are fitted to the top and sides of each. Other sacks are pumped full of propellant, and balloon into the shapes of globes and cylinders. Soon the three moon-going spaceships begin to emerge in their final form. The two round trip ships resemble an arrangement of hourglasses inside a metal framework, but instead of hourglasses they have central structures which look like great silos.
For Protection Against Meteors. To guard against meteors, all vital parts of the three craft-propellant tanks, personnel spheres, cargo cabin-are given a thin covering of sheet metal, set on studs which leave at least a one-inch space between this outer shield and the inside wall. The covering, called a meteor bumper, will take the full impact of the flying particles (we don't expect to be struck by any meteors much larger than a grain of sand) and will cause them to disintegrate before they can do damage.
For protection against excessive heat, all parts of the three rocket ships are painted white, because white absorbs little of the sun's radiation. Then, to guard against cold, small black patches are scattered over the tanks and personnel spheres. The patches are covered by white blinds, automatically con trolled by thermostats. When the blinds on the sunny side are open, the spots absorb heat and warm the cabins and tanks; when the blinds are closed, an all-white surface is exposed to the sun, permitting little heat to enter. When the blinds on the shaded side are open, the black spots radiate heat and the temperature drops.
Now we're ready to take off from the space station's orbit to the moon. The bustle of our departure-hurrying space taxis, the nervous last-minute checks by engineers, the loading of late cargo, and finally the take-off itself- will be watched by millions. Television cameras on the space station will transmit the scene to receivers all over the world. And people on the earth's dark side will be able to turn from their screens to catch a fleeting glimpse of light- high in the heavens-the combined flash of ninety rocket motors, looking from the earth like the sudden birth of a new short-lived star.
Our departure is slow. The big rocket ships rise ponderously, one after the other, green flames streaming from their batteries of rockets, and then they pick up speed. Actually, we don't need to gain much speed. The velocity required to get us to our destination is 19,500 miles an hour, but we've had a running start; while "resting" in the space station's orbit, we were really streaking through space at 15,840 miles an hour. We need an additional 3,660 miles an hour.
Thirty-three minutes from take-off we have it. Now we cut off our motors; momentum and the moon's gravity will do the rest.
The moon itself is visible to us as we coast through space, but it's so far off to one side that it's hard to believe we won't miss it. In the five days of our journey, though, it will travel a great distance, and so will we; at the end of that time we shall reach the farthest point, or apogee, of our elliptical course, and the moon should be right in front of us.
The earth is visible, too-an enormous ball, most of it bulking pale black against the deeper black of space, but with a wide crescent of daylight where the sun strikes it. Within the crescent, the continents enjoying summer stand out as vast green terrain maps surrounded by the brilliant blue of the oceans. Patches of white cloud obscure some of the detail; other white blobs are snow and ice on mountain ranges and polar seas.
Against the blackness of the earth's night side is a gleaming spot-the space station, reflecting the light of the sun.
Two hours and fifty-four minutes after departure, we are 17,750 miles from the earth's surface. Our speed has dropped sharply, to 10,500 miles an hour. Five hours and eight minutes en route, the earth is 32,950 miles away, and our speed is 8,000 miles an hour; after twenty hours, we're 132,000 miles from the earth, traveling at 4,300 miles an hour.
On the first day, we discard the empty departure tanks. Engineers in protective suits step outside the cabin, stand for a moment in space, then make their way down the girders to the big spheres. They pump any remaining propellant into reserve tanks, disconnect the useless containers, and give them a gentle shove. For awhile the tanks drift alongside us; soon they float out of sight. Eventually they will crash on the moon.
There is no hazard for the engineers in this operation. As a precaution, they were secured to the ship by safety lines, but they could probably have done as well without them. There is no air in space to blow them away.
That's just one of the peculiarities of space to which we must adapt ourselves. Lacking a natural sequence of night and day, we live by an arbitrary time schedule. Because nothing has weight, cooking and eating are special problems. Kitchen utensils have magnetic strips or clamps so they won't float away. The heating of food is done on electronic ranges. They have many advantages: they're clean, easy to operate, and their short-wave rays don't burn up precious oxygen.
Difficulties of Dining in Space. We have no knives, spoons, or forks. All solid food is precut; all liquids are served in plastic bottles and forced directly into the mouth by squeezing. Our mess kits have spring-operated covers; our only eating utensils are tonglike devices; if we open the covers carefully, we can grab a mouthful of food without getting it all over the cabin.
From the start of the trip, the ship's crew has been maintaining a round-the clock schedule, standing eight-hour watches. Captains, navigators, and radio men spend most of their time checking and rechecking our flight track, ready to start up the rockets for a change of course if an error turns up. Technicians back up this operation with reports from the complex and delicate "electronic brains"-computers, gyroscopes, switchboards, and other instruments-on the control deck. Other specialists keep watch over the air-conditioning, temperature, pressure, and oxygen systems.
But the busiest crew members are the maintenance engineers and their assistants, tireless men who have been bustling back and forth between ships since shortly after the voyage started, anxiously checking propellant tanks, tubing, rocket motors, turbopumps, and all other vital equipment. Excessive heat could cause dangerous hairline cracks in the rocket motors; unexpectedly large meteors could smash through the thin bumpers surrounding the propellant tanks; fittings could come loose. The engineers have to be careful.
We are still slowing down. At the start of the fourth day, our speed has dropped to 800 miles an hour, only slightly more than the speed of a conventional jet fighter. Ahead, the harsh surface features of the moon are clearly out lined. Behind, the blue-green ball of the earth appears to be barely a yard in diameter.
Our fleet of unpowered rocket ships is now passing the neutral point between the gravitational fields of the earth and the moon. Our momentum has dropped off to almost nothing, yet we're about to pick up speed. For now we begin falling toward the moon, about 23,600 miles away. With no atmosphere to slow us, we'll smash into the moon at 6,000 miles an hour unless we do something about it.
Rotating the Moon Ship. This is what we do: aboard each ship, near its center of gravity, is a positioning device consisting of three flywheels set at right angles to one another and operated by electric motors. One of the wheels heads in the same direction as our flight patch-in other words, along the longitudinal axis of the vehicle, like the rear wheels of a car. Another parallels the latitudinal axis, like the steering wheel of an ocean vessel. The third lies along the horizontal axis, like the rear steering wheel of a hook-and-ladder truck. If we start any one of the wheels spinning, it causes our rocket ship to turn slowly in the other direction (pilots know this "torque" effect; if increased power causes a plane's propeller to spin more rapidly in one direction, the pilot has to fight his controls to keep the plane from rolling in the other direction) .
The captain of our spaceship orders the longitudinal flywheel set in motion. Slowly our craft begins to cartwheel; when it has turned half a revolution, it stops. We are going toward the moon tail-end-first, a position which will enable us to brake our fall with our rocket motors when the right time comes.
Tension increases aboard the three ships. The landing is tricky-so tricky that it will be done entirely by automatic pilot, to diminish the possibility of human error. Our scientists compute our rate of descent, the spot at which we expect to strike, the speed and direction of the moon (it's traveling at 2,280 miles an hour at right angles to our path). These and other essential statistics are fed into a tape. The tape, based on the same principle as the player-piano roll and the automatic business-machine card, will control the automatic pilot. (Actually, a number of tapes intended to provide for all eventualities will be fixed up long before the flight, but last-minute checks are necessary to see which tape to use, and to see whether a manual correction of our course is required before the autopilot takes over.)
Now we lower part of our landing gear-four spiderlike legs, hinged to the square rocket assembly, which have been folded against the framework.
As we near the end of our trip, the gravity of the moon, which is still to one side of us, begins to pull us off our elliptical course, and we turn the ship to conform to this change of direction. At an altitude of 550 miles, the rocket motors begin firing; we feel the shock of their blasts inside the personnel sphere and suddenly our weight returns. Objects which have not been secured before hand tumble to the floor. The force of the rocket motors is such that we have about one third our normal earth weight.
The final ten minutes are especially tense. The tape-guided automatic pilots are now in full control. We fall more and more slowly, floating over the landing area like descending helicopters. As we approach, the fifth leg of our landing gear-a big telescopic shock absorber which has been housed in the center of the rocket assembly-is lowered through the fiery blast of the motors. The long green flames begin to splash against the baked lunar surface. Swirling clouds of brown-gray dust are thrown out sideways; they settle immediately, instead of hanging in air, as they would on the earth.
The broad round shoe of the telescopic landing leg digs into the soft volcanic ground. If it strikes too hard, an electronic mechanism inside it immediately calls on the rocket motors for more power to cushion the blow. For a few seconds, we balance on the single leg. Then the four outrigger legs slide out to help support the weight of the ship, and are locked into position. The whirring of machinery dies away. There is absolute silence. We have reached the moon.
From the book "Man and the Moon"
Chapter by Wernher van Braun page 96-102
Published by the World Publishing Company
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