ENGINEERS planning vehicles for excursions into space are inevitably attracted to the greatest source of energy we know — the sun. Solar energy is ever renewing. Clouds are no problem outside our atmosphere; “nights" are merely the brief periods a satellite is in the shadow of the earth or a planet. As a source of auxiliary power or energy for propulsion, the sun offers advantages.
Solar energy is already being utilized for auxiliary power. Vanguard I has been reporting from space with a 1 /200-watt radio transmitter powered by six solar batteries that use selenium cells to convert sunlight into electrical energy. This operation will be carried much further in the “paddlewheel" satellite now planned as a prototype of a probe to be sent eventually for a look at Venus. This satellite will have four fins, resembling huge paddles, which will be packed with solar batteries. The design provides a maximum surface to expose the cells to sunlight and makes certain that at least one fin will always be turned toward the sun.
Yet even this ambitious project is only a primitive beginning. Designers are thinking in terms of satellites that will need as much as 4 kilowatts of auxiliary power, or 800,000 times the Vanguard’s supply. Two scientists at the National Aeronautics and Space Administration’s Langley Research Center, Albert E. von Doenhoff and Joseph M. Hallissy, Jr., have explored a number of alternative methods for using solar energy to produce this power.
Sunlight would be collected by an extremely lightweight reflector resembling an enormous plastic umbrella. Such unwieldy structures are quite feasible in space, where there is no aerodynamic drag. The heat gathered at the focal point of this huge mirror would be used to vaporize a liquid to drive an engine. If the liquid used were mercury, the engine would operate much like a steam engine, and the whole system, including the collector and the necessary generator, would weigh 855 pounds. An alternate system would use liquid sodium to introduce heat into and remove it from a heat engine. This would result in savings in the size and weight of the heat collector, the storage system, and the boiler; the whole unit would weigh only about 580 pounds.
Solar energy for propulsion
Other engineers are looking ahead to power not for auxiliary needs but to propel vehicles through space. Experts at Los Alamos and a Columbia physicist have separately proposed propulsion systems that would make use of the pressure of sunlight in much the same way that a sailing ship makes use of wind pressure. The pressure of light is small, amounting only to about 1/100 of a pound per acre of the earth’s surface. Unlike a ship, however, a vehicle moving through space does not require a large source of energy, since it does not have to overcome the resistance of the sea.
Dr. Theodore P. Cotter and his associates at Los Alamos propose that a 350-foot circular satellite carrying a 25-pound payload be put in orbit around the earth with a device that would automatically open a large sail of thin plastic film. Radio signals from the earth would spread the sail while the satellite moves away from the sun and turn it edgewise while the satellite moves toward the sun. The quarter-mile-wide sail— weighing only 1000 pounds — would gradually speed up the satellite until it moved out into space. The Los Alamos scientists estimate that this sunjammer would take about two and a half years to travel to Mars and back.
A similar propulsion system has been proposed by Professor Richard L. Garwin of Columbia University. He suggests a small satellite unit with an aluminized plastic sail 230 feet in diameter, attached to the satellite by thin ribbons of plastic 650 feet long. An automatic sail-furling system would be operated by a solar battery.
A quite different system has been suggested by Krafft A. Ehricke, German-born rocket expert who is a division chief at Convair. His ship would use the radiant energy of the sun to heat a propellent gas for a jet engine.
Ehricke’s design is no streamlined space rocket. It looks like a golf ball squeezed between two basketballs. The “ball” is a small sphere containing liquid hydrogen. The two big outer spheres, 128 feet in diameter, are the sunshine traps. They are built of extremely thin plastic, and half of their inner surfaces have a metallic coating, providing two hemispherical reflectors that can be rotated to catch the sun’s rays no matter in what direction the ship is headed.
The propulsion system of Ehricke’s ship pumps liquid hydrogen from the tank at minus-420 degrees Fahrenheit to heating areas set along the focal axes of the reflectors. Here the concentrated rays of the sun heat the hydrogen to plus-1540 degrees Fahrenheit. Piped to a nozzle fastened astern of the central sphere, the hot gas is spewed out, providing some 100 to 200 pounds of thrust. The ship is steered by changing the direction of the propulsion nozzle. The two-man crew rides in a gondola.
Ehricke points out that such a solar-energy-powered craft has certain disadvantages. The thrust that can be achieved from the diffused energy of sunlight is relatively small, so that the craft must he very lightly built. Small meteors might damage the bubblelike reflector spheres, or cosmic dust sharply cut down their efficiency. Even if all the engineering problems are solved, Ehricke believes that such a space craft would have only enough power for lunar exploration or travel in the region between the earth and the moon.
Atomic oxygen for power
A third solar propulsion system is proposed not for outer space but for the upper atmosphere. Here, some sixty miles out from the earth, the molecules of atmospheric oxygen have been broken apart into single atoms by the radiant energy of sunlight. When this so-called atomic oxygen is recombined into molecular form, there is a large release of energy. Three scientists of AerojetGeneral Corporation — S. T. Demetriades, G. B. Kretchmer, and M. Father — suggest using this energy to drive a low-altitude satellite.
The vehicle would pick up the oxygen atoms and compress them by its own speed, re-forming molecules and releasing energy for propulsion. The concept has a certain resemblance to a locomotive running over a coal outcrop and scooping up its fuel as it goes.
The ram-jet effect required by the satellite, however, could be achieved only at speeds several times that of sound. Since the density of the atmosphere at a sixty-mile altitude is only one millionth of what it is at sea level, the available power released would be necessarily small, requiring that the vehicle be extremely light, possibly made of thin metal foil. The scientists have prepared a preliminary design of a ram-jet atomic-oxygen power plant for the Air Force office of Scientific R esearch.
Repairing a damaged retina
A beam of light four times as intense as the sun’s rays is being used to “weld” human eyes. Surgeons at Columbia Presbyterian Medical Center in New York are repairing tiny rents in the retina (the lightabsorbent cells of the eye) by a process they call photo-coagulation. The beam from a superarc lamp is aimed into the anesthetized eye through a series of lenses. The transparent lens of the eye itself further concentrates the beam to produce a ½-mm. burn alongside the retinal tear.
A circle of these tiny burns around the rent causes the blood vessels back of the retina to emit an adhesive fluid, which seals the damaged area and prevents the retina from becoming detached from the tissue beneath. The method cannot be used after detachment occurs; the five thousand cases of retinal detachment that U.S. eye doctors see each year must be dealt with by complex and delicate surgery.
The Zeiss-made photo-coagulator —invented by a Bonn physician is also used to treat some eye tumors, particularly retinoblastoma in infants, and certain blood vessel tumors. In Germany, according to one ophthalmologist, the instrument is used to treat malignancies in the eye, but U.S. physicians avoid this technique for fear it will cause the cancer to spread.
The fish horn bellowing across the meadow or the farm wife’s voice strained to breaking point as she tries to shout above the noise of the tractor may soon become rustic memories. Farmers are able to telephone from anywhere on the farm — with combination loudspeaker and extension systems tailored by Bell Telephone to fit the communications needs of an individual farm.
A typical system may include several extensions in house, barn, and other buildings — even in a booth in a field — and outside two-way loudspeakers mounted on barn walls or roof, connected with all extensions. All the equipment is connected to the main telephone in the house, where the farmer’s wife, with a simplified switchboard, can hold calls while she consults her husband. If she transfers the call to him, he can answer into one of the two-way loudspeakers without even getting down from his tractor seat.
Open microphones in the barn pick up the noises of the stock at the flick of a switch to assure the farmer at his dinner table that all is well. Months of interviewing farmers went into the new system, now being tried out in test areas.
Prefabrication is being applied to road building in Germany. Instead of being poured on the spot, concrete is cast in big slabs in a factory, unhampered by weather conditions or delays in preliminary preparations. The base is prepared as usual, the slabs brought to the site in special trailer trucks and lowered onto the foundation by cranes. A final asphalt layer is added, but German engineers are experimenting with using the slabs without the asphalt.
The German company using the new method claims that in a typical job prefabrication saved seven weeks, although costs were 10 per cent higher. The system is particularly suited to heavily traveled highways or important access roads that must be finished as quickly as possible.
Meanwhile, Dr. Ronald Scott of California Institute of Technology sees a day coming when roads will be made by a machine that will move over the ground, picking up dirt in front, mixing in chemicals, and spewing the treated dirt out in back to form a completed road surface. As soon as the mixture sets, it will be as serviceable as a concrete road.
Dr. Scott points out that a desert’s dry lake beds — such as Bonneville Salt Flats in Utah — are hard enough to take auto and aircraft traffic because natural salts and alkalies have bound together their silts and earth just as cement binds sand and gravel into concrete. A wide variety of chemicals may be used as stabilizers to duplicate the process. One already in use is sulphite liquor, a waste product of the paper industry. Even molasses has been used successfully for earth stabilization, according to Dr. Scott.
Anyone who has ever had an overloaded grocery bag split open and spill its contents will appreciate the latest invention of 84-year-old Sanford Cluett. The man who invented pre-shrinking for shirt collars and dresses has applied shrinkage to paper to produce paper bags that stretch with the load instead of tearing. Now being jointly licensed by Cluett Peabody and West Virginia Pulp and Paper, for manufacture under the trade name Clupak, the stretchable paper is already being used for cement and fertilizer sacks, as well as grocery bags.
Clupak bags look like ordinary paper but have from three to twelve times the stretch. The result is a bag five times as tough as conventional kraft paper. The new paper gets its stretchability through a completely mechanical process. A moist web of paper, still in plastic form, is squeezed against an endless rubber blanket that has been stretched by passing over a roller. As the rubber shrinks back to its original size, the paper shrinks with it. The amount of shrinkage in this process determines the amount of stretch in the fmished product.
The licensers suggest a wide range of uses, including disposable clothing, uniforms, hospital bed sheets, towels, printing papers, building papers, air-lift parachutes, and saddle blankets.
Nylon printing plate
Nylon has come a long way from the hosiery field, where it got its start. One of the most interesting new uses is in a light, strong, and extremely accurate printing plate developed by Time Inc. and Arthur D. Little. The plate, a nylon composition mounted on aluminum, is pre-sensitized, eliminating one step.
Additional time is saved by combining development and relief etching in a single process after the image has been projected on the nylon with ultraviolet light. The nylon plate is said to have such a close tolerance — plus or minus .0005 inches — that no adjustment is needed after it has been locked on the press.
Alcohol without hangovers
Dr. Robert Carroll, a chemical consultant, and Dr. Lawrence C. O’Brien, of Perkin-Elmer Corporation, report they have found a way to distinguish between those ingredients of an alcoholic beverage that cause hangovers and those that make it taste and smell good. Now they are working on ways to distill alcoholic liquors relatively free of the fusel oil and acetaldehyde that make trouble, yet preserving characteristic flavor and aroma. If successful, such a process would cut short or even eliminate the expensive aging now necessary to make many liquors palatable.
Partisan drinkers may be glad to hear that vodka and gin contain less of the undesirable chemicals than other forms. Of the various types of whiskies, Scotch has the lowest hangover potential from the chemical point of view.