Next Stop — the Moon
GEORGE H. WALTZ, JR.
Some rocket men hope to zip to the moon and back in this generation. It’s no trick at all — once you lick gravity
IF, A FEW years back, you had read about a proposed future trip by rocket to the moon you probably would have labelled the yarn’s author a crackpot visionary or you would have passed the whole thing off as pure unadulterated fiction. Not so today. A rocket to the moon no longer is a 19thcentury Jules Verne dream concocted to amuse. It is a good probability—a possibility, according to the top rocket experts, within 20 years!
The thinking, design, research and experimentation all are well under way. The first German V-2 that soared 60 miles into the clouds over its Frenchcoast launching site in the late hours of Sept. 8, 1944, and pointed its deadly nose toward London, literally made the first blaze in the long trail toward the moon. Today, three years later, we are climbing higher and higher into space. As Dr. Fritz Zwicky, one of the U. S.’s top rocket authorities at the California Institute of Technology, puts it, “We first throw a little something into the skies. Then a little more. Then a shipload of instruments. Then ourselves.”
And Dr. Zwicky keeps good company in his prophecy. Dr. James Van Allen, Johns Hopkins University’s rocket expert, makes a definite prediction—an unmanned, one-way rocket to the moon within 15 years! Major P. C. Calhoun, head of the Army Air Force’s guided-missiles experiments, goes even further. He hopes to travel to the moon and back in his lifetime. G. Edward Pendray, long-time believer in the future of rocket power and one of the founders of the American Rocket Society, says, “The conquest of space is now only a matter of time and engineering and some of us probably will live to read the story of the exploration and colonization of the moon by visitors from the earth.”
Battling with Gravity
INCREDIBLE, you say. Well, so was the thought of atomic power and atomic bombs or supersonic airplanes not too long ago. In today’s fast-moving world the engineers and the scientists seem to be able to make what was incredible yesterday become fact by tomorrow.
Let’s investigate the problems involved in firing a crewless, instrument-filled rocket at the moon and then check the basic requirements against the present-day score of rocket research.
The main problem in the design of a space rocket is one of speed—speed enough first to overcome the resistance of the air that covers our globe like the rind of a melon and, second, enough speed to overcome the downward pull of the earth’s force of gravity. Fortunately, the problem is simplified somewhat by the fact that if you can attain sufficient speed to counterbalance gravity—roughly seven miles a second or about 25,000 miles an hour at the earth’s surface—the rocket very soon in its flight will be in outer space where there is no air, and therefore no air resistance, and it literally will be able to coast to its target.
If that figure of 25,000 miles an hour jogged your head back as being a bit on the fantastic side, reserve your decision. Germany’s V-2’s hit a speed of 3,600 miles an hour in their upward flight and a new rocket being developed for the U. S. Navy will soar up into the sky at a top speed of 5,750 miles an hour, powered by standard present-day rocket fuels. What a rocket powered by atomic energy would
clock is anyone’s guess, but a good many scientists right now are seeking the answer.
What’s more, the V-2’s and lhe U. S. Navy’s new rocket are what the experts call “single-stage rockets.” They are powered by a single-stage engine and must carry that engine and its fuel tanks even after the alcohol and oxygen they burn are exhausted and they have reached their top speed. Unnecessary weight after complete acceleration means less efficiency. The answer to space travel, say the rocket men, is a multiple-stage rocket a series of independent detachable rockets and engines arranged one inside the other like the sections of a partially closed telescope and fueled not by alcohol and liquid oxygen, but by liquid hydrogen and liquid oxygen. Since the speed of a rocket depends on the heat of its exhaust gases, and, except for atomic fission, the combination of hydrogen and oxygen to form water produces more heat per pound of fuel than any other simple reaction, they seem to be the best present-day fuels.
The first stage or engine would launch the multiple rocket and boost it several hundred miles into the air. Then, when its fuel was exhausted, it, together with its fuel tanks, would drop off and the second stage or engine would Like over. As each stage completed its job and was dropped free, the rocket not only would be gaining in speed but losing in weight until the final stage would be pushing itself through outer space at the 25,000 miles an hour required to free it of the earth’s pull of gravity. As the rocket soared closer and closer to the moon the engine in the final stage could be throttled down and used primarily for steering—the rocket’s blast being directed at movable tail rudders which would deflect the driving force to change the rocket’s direction and keep it on its course. At a point
considerably more than halfway along the average 240,000mile route from the earth to the moon, the gravitational pull of the earth no longer would be felt and the rocket would enter the sphere of gravitational pull from the moon. If the rocket’s speed in space could be controlled so that it barely crept across this line of equal attractions, it would then gradually speed up and reach the surface of the moon at about two miles a second.
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Next Stop — the Moon
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Such a crewless, multiple-stage moon rocket would not have to be unusually large. California Institute of 'Technology rocket experts visualize it as a fivestage affair about 75 feet long—about twice the size of a German V-2. It would be a potshot projectile aimed at some desired target on the moon. During the course of its flight, automatic recording and radio equipment would flash such data as accelerations, temperatures, strengths of radio activity and cosmic rays, the effects of gravity, and air densities back to listeners on the earth. If the radio and recording
equipment were mounted in a shockproof, armor-plate cabinet designed to withstand the crash on the moon, it could continue to send out “on-themoon” reports until its storage-battery power was exhausted.
As techniques and rocket engines and fuels improve, it should be possible to design a multiple-stage, instrumentcarrying rocket to soar completely around the moon and return to the earth. This undoubtedly will be the scientist’s second try into space. In such a rocket automatic cameras as well as automatic recording instrumonts will bring back a wealth of scientific data, as well as pictures of the other side of the moon—something no earthly human ever has seen.
How Fast Can You Go?
The main problem then in the construction of a crewless space rocket principally is one of engineering and rocket-engine design. In a crewed rocket, however, which is the ultimate goal, the problems of the reactions and limitations of the human body are involved.
Fortunately speed, as such, has little or no effect on the human body. Right at this moment, you, as a human on the face of the earth, are travelling around the sun at a speed of 20 miles a second (almost three times faster than the necessary speed for a moon rocket), yet you experience no sensation. When you drive your car your greatest sensation of movement is during the time you are gaining speed, not after you have attained it. It is not speed that we have to worry about, but changes in speed or acceleration.
Scientists like to express acceleration or change of motion in terms of the force of gravity. To them, a one G acceleration is the rate of change of speed of a freely falling body under the influence of nothing but the force of gravity. If you remember some of your school science you will recall that that amounts to an acceleration of 32 feet u second for every second of fall, discounting air resistance. If you carry out the necessary multiplication and division to translate that into miles an hour for every hour of fall, you will find, believe it or not, that every time you dive off the high board at vour favorite swimming pool or jump down a few steps your body is accelerating at a rate of about 78,000 miles an hour for every hour.
We know, then, that an acceleration of one G (or 78,000 miles an hour) can’t hurt us. We live with it 24 hours a day. The pilots of fast pursuit airplanes during manoeuvres often subject themselves to five Gs or six Gs for short periods. The ability to withstand high G forces without ill effects varies with the individual, but tests have shown that with practice the average person can stand an acceleration of three to four Gs without pulling enough blood away from the brain to black-out.
Suppose for our theoretical moon rocket we settle on a fairly safe maximum acceleration of three and one half Gs and see where our calculations bring us out with respect to speed, time and altitude. An acceleration of three and one half Gs would mean an acceleration three and one halftimes that of the normal pull of gravity or approximately 265,000 miles an hour for every hour (three and one half times 78,000). With such an acceleration we would reach the 25,000-mile-an-hour speed of liberation necessary to escape the earth’s pull of gravity in a trifle more than five and one half minutes at an altitude of about 700 miles, well out of the earth’s atmosphere.
No Joy Ride
Since the earth’s pull of gravity decreases as we move away from the earth, the rocket’s speed could be cut down gradually until, as it reached the point of equal gravitational pulls from the earth and the moon, it would be j approaching zero. The pull of the moon then would take over and the rocket ! would gather speed.
The first human to attempt a trip to ! the moon—or around the moon—via | such a rocket will be embarking on no j week-end joy ride. He will have to be ¡
reconciled to the possibility of miscalculations, equipment failure, and collision with a meteor. His quarters by necessity will be cramped, his food rations small, and if he conserves fuel by travelling at the minimum necessary velocities, the nonstop round-trip flight will take him about a week—four days to the moon and three days back. The differences in time between the “going and “return” trips will be caused by the fact that on the outward trip his rocket will be fighting against the earth’s pull of gravity for most of the way while on the return trip that same pull of gravity will be helping him most of the way.
Because the gravitational pull of the moon is only about one fifth that of the earth the pilot will need comparatively little of the rocket’s remaining power to escape the moon’s gravity on the return trip and reach the helping pull of the earth.
The rocket’s descent to the earth’s surface will be no direct plunge. Such a manoeuvre, because of the rocket’s speed and the increasing air resistance, would he likely to heat it to incandescence. Instead, by diving his rocket deeper and deeper into the earth’s atmosphere as he circles the earth in an ever-diminishing spiral, the pilot will use the resistance of the earth’s air for short intervals at a time to slow him down more and more. With each succeeding dip into the earth’s atmosphere from outer space, the rocket will lose speed until finally its speed will be low enough to allow further slowing by the successive openings of a series of “braking parachutes.” Finally, when the speed is low enough, a large parachute will open to lower the rocket safely to earth. The story that pioneer rocket pilot tells will pave the way to your first trip to the moon.
At the present time, any description of what the first large passengercarrying, multiple-stage rocket to the moon will look like can be little more than pure prophecy. However, based on facts that are known, a rough sketch can be drawn.
First of all, it will be no small affair. To carry the necessary fuel and the equipment and supplies for its crew and a small number of passengers will require a rocket about as long as the channel span of the Montreal Harbor Bridge (about 1,100 feet). Poised on end, for its take-off from the earth, it would tower just about as high as New York’s famed Empire State Building. Its launching weight, it has been estimated, would be in the neighborhood of 50,000 tons, although the final stage that reaches the moon will weigh only 50 tons.
At take-off, the crew and passengers, in their compartments up near the nose or top and final stage, would be strapped in full-reclining seats adjusted so that their bodies would be horizontal and at right angles to the direction of motion. This supine position would reduce the effects of acceleration to a minimum by presenting the smallest possible column of blood or movement of internal organs to the effects of the three and one half Gs acceleration force.
Floating in Space
Once the power is shut off and the rocket begins to coast toward the moon, the passengers would be weightless and would probably find it less dangerous to remain strapped in their seats than to float through the air like atmospheric swimmers.
Thick quartz or special plastic windows would give them a good view of
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grow smaller and smaller and the moon larger and larger.
To ease his 50-ton space ship to a gradual stop on the face of the moon, the pilot would turn his rocket around, so, as it descends stem-first under the pull of the moon’s gravity, he can use his rocket’s jet as a buffer to slow him down. If a good upright landing is made, his rocket then would be in a launching position for its take-off for the trip back to earth.
During the space flight, an air-conditioning and oxygen system would take care of the “atmospheric” needs of the passengers and crew. To venture out on the surface of the moon, however, they would have to don special lunar suits to provide them with a normal earth atmosphere—sort of diving suits in reverse that would not
only supply the wearer with oxygen but a normal earth atmosphere of 15 pounds per square inch plus heat for the frigid lunar nights and cooling for the broiling lunar days. Eventually, in the minds of such moon-rocket enthusiasts as Pendray and Ley, vast underground lunar cities would eliminate the need for bulky lunar suits.
But this is speculation. Man has yet to break the bonds of gravity that shackle him to this globe, before he can consider colonizing or conquering another orb. Yet, year by year, as he reaches farther into the cold depths of the vacuum of space, the placid, human face of the moon looms larger. One day, perhaps not so very far in the future, the first moon traveller will step from his rocket onto the lonely surface of the earth’s satellite. When this happens, the Planetary Age will have begun. ic