by Isaac Asimov
Around the beginning of the twentieth century, two men independently conceived a new and finer use of rockets—exploring the upper atmosphere and space. They were a Russian, Konstantin Eduardovich Tsiolkovsky, and an American, Robert Hutchings Goddard. (It is odd indeed, in view of later developments, that a Russian and an American were the first heralds of the age of rocketry, though an imaginative German inventor, Hermann Ganswindt, also advanced even more ambitious, though less systematic and scientific, speculations at this time.)
The Russian was the first in print; he published his speculations and calculations in 1903 to 1913, whereas Goddard did not publish until 1919. But Goddard was the first to put speculation into practice. On 16 March 1926, from a snow-covered farm in Auburn, Massachusetts, he fired a rocket 200 feet into the air. The remarkable thing about his rocket was that it was powered by a liquid fuel, instead of gunpowder. Then, too, whereas ordinary rockets, bazookas, jet planes, and so on make use of the oxygen in the surrounding air, Goddard’s rocket, designed to work in outer space, had to carry its own oxidizer in the form of liquid oxygen (lox, as it is now called in missile-man slang).
Jules Verne, in his nineteenth-century science fiction, had visualized a cannon as a launching device for a trip to the moon, but a cannon expends all its force at once and at the start, when the atmosphere is thickest and offers the greatest resistance. The total acceleration required, moreover, is attained at the very start and is great enough to crush any human beings inside the spaceship into a bloody mash of flesh and bone.
Goddard’s rockets moved upward slowly at first, gaining speed and expend ing final thrust high in the thin atmosphere, where resistance is low. The gradual attainment of speed means that acceleration is kept at bearable levels, an important point for manned vessels.
Unfortunately Goddard’s accomplishment got almost no recognition, except from his outraged neighbors, who managed to have him ordered to take his experiments elsewhere. Goddard went off to shoot his rockets in greater privacy; and, between 1930 and 1935, his vehicles attained speeds of as much as 550 miles an hour and heights of a mile and a half. He developed systems for steering a rocket in flight and gyroscopes to keep a rocket headed in the proper direction. Goddard also patented the idea of multistage rockets. Be cause each successive stage sheds part of the original weight and starts at a high velocity imparted by the preceding stage, a rocket divided into a series of stages can attain much higher speeds and greater heights than could a rocket with the same quantity of fuel all crammed into a single stage.
During the Second World War, the United States Navy halfheartedly supported further experiments by Goddard. Meanwhile, the German government threw a major effort into rocket research, using as its corps of workers a group of youngsters who had been inspired primarily by Hermann Oberth, a Rumanian mathematician who, in 1923, had written on rockets and space craft independently of Tsiolkovsky and Goddard. German research began in 1935 and culminated in the development of the V-2. Under the guidance of the rocket expert Wernher von Braun (who, after the Second World War, placed his talents at the disposal of the United States), the first true rocket missile was shot off in 1942. The V-2 came into combat use in 1944, too late to win the war for the Nazis, although they fired 4,300 of them altogether, of which 1,230 hit London. Von Braun’s missiles killed 2,511 Englishmen and seriously wounded 5,869 others.
On 10 August 1945, almost on the very day of the war’s end, Goddard died—just in time to see his spark blaze into flame at last. The United States and the Soviet Union, stimulated by the successes of the V-2, plunged into rocket research, each carrying off as many German experts in rocketry as could be lured to its side.
At first, the United States used captured V-2’s to explore the upper atmo sphere; but by 1952, the stock of these rockets was used up. By then, larger and more advanced rocket-boosters were being built in both the United States and the Soviet Union, and progress continued.
EXPLORING THE MOON
A new era began when, on 4 October 1957 (within a month of the hundredth anniversary of Tsiolkovsky’s birth), the Soviet Union put the first man-made satellite (Sputnik I) in orbit. Sputnik I traveled around Earth in an elliptical orbit—156 miles above the surface (or 4,100 miles from Earth’s center) at perigee and 560 miles away at apogee. An elliptical orbit is some thing like the course of a roller coaster. In going from apogee to perigee, the satellite slides downhill, so to speak, and loses gravitational potential. Thus, velocity increases, so that at perigee the satellite starts uphill again at top speed, as a roller coaster does. The satellite loses velocity as it climbs (as does the roller coaster) and is moving at its slowest speed at apogee, before it turns downhill again.
Sputnik I at perigee passed through wispy bits of the upper atmosphere; and the air resistance, though slight, was sufficient to slow the satellite a bit on each trip. On each successive revolution, it failed to attain its previous apogee height. Slowly, it spiraled inward. Eventually it lost so much energy that it yielded to Earth’s pull sufficiently to dive into the denser atmosphere, there to be burned up by friction with the air.
The rate at which a satellite’s orbit decays in this way depends partly on the mass of the satellite, partly on its shape, and partly on the density of the air through which it passes. Thus, the density of the atmosphere at that level can be calculated. The satellites have given us the first direct measurements of the density of the upper atmosphere. The density proved to be higher than had been thought; but at the altitude of 150 miles, for instance, it is still only 1 ten-millionth of that at sea level and, at 225 miles, only 1 trillionth.
These wisps of air ought not be dismissed too readily, however. Even at a height of 1,000 miles, where the atmospheric density is only 1 quadrillionth the sea-level figure, that faint breath of air is a billion times as dense as the gases in outer space itself. Earth’s envelope of gases spreads far outward.
The Soviet Union did not remain alone in this field but, within four months, was joined by the United States, which, on 30 January 1958, placed in orbit its first satellite, Explorer 1.
Once satellites had been placed in orbit about Earth, eyes turned more longingly than ever toward the moon. To be sure, the moon had lost some of its glamour, for though it was a world and not just a light in the sky, it was no longer the world it was thought to be in earlier times.
Prior to Galileo’s telescope, it had always been assumed that if the heavenly bodies were worlds, they would surely be filled with living things, even intelligent humanoid living things. The early science-fiction stories about the moon made this assumption, as did later ones, right into the twentieth century.
In 1835, an English writer named Richard Adams Locke wrote a series of articles for the New York Sun which purported to describe serious scientific studies of the moon’s surface, which discovered many kinds of living things. The descriptions were detailed and were promptly believed by millions of people. And yet it had not been long after Galileo looked at the moon through his telescope that it began to seem clear that life could not exist on the moon. The moon’s surface was never obscured by cloud or mist. The dividing line between light and dark hemispheres was always sharp, so that there was no detectable twilight. The dark “seas” that Galileo thought to be bodies of water were found to be speckled with small craters; they were, at best, relatively smooth bodies of sand. It was soon clear that the moon contained no water and no air—therefore, no life.
Still, it was perhaps too easy to come so quickly to this conclusion. What about the moon’s hidden side that human beings never saw? Might there not be scraps of water under the surface, which, if insufficient to support large forms of life, might support the equivalent of bacteria? Or, if there were no life at all, might there not be chemicals in the soil that represented a slow and possibly aborted evolution toward life? And even if there were nothing of that kind, there were still questions to be answered about the moon that had nothing to do with life. Where was it formed? What wa
s its mineralogical structure? How old was it?
It was therefore not long after the launching of Sputnik I that the new technique began to be used to explore the moon. The first successful moon probe—that is, the first satellite to pass near the moon—was sent up by the Soviet Union on 2 January 1959. It was Lunik I, the first man-made object to take up an orbit about the sun. Within two months, the United States had duplicated the feat.
On 12 September 1959, the Soviets sent up Lunik II and aimed it to hit the moon. For the first time in history, a man-made object rested on the surface of another world. Then, a month later, the Soviet satellite Lunik III slipped beyond the moon and pointed a television camera at the side we never see from Earth. Forty minutes of pictures of the other side were sent back from a distance of 40,000 miles above the lunar surface. They were fuzzy and of poor quality but showed something interesting. The other side of the moon had scarcely any maria of the type that are so prominent a feature of our side. Why this asymmetry should exist is not entirely clear. Presumably the maria were formed comparatively late in the moon’s history, when one side already faced Earth forever and the large meteors that formed the seas were slanted toward the near face of the moon by Earth’s gravity.
But lunar exploration was only beginning. In 1964, the United States launched a moon probe, Ranger 7, which was designed to strike the moon’s surface, taking photographs as it approached. On 31 July 1964, it completed its mission successfully, taking 4,316 pictures of an area now named Mare Cognitum (“known sea”). In early 1965, Ranger 8 and Ranger 9 had even greater success, if that were possible. These moon probes revealed the moon’s surface to be hard (or crunchy, at worst) and not covered by the thick layer of dust some astronomers had suspected might exist. The probes showed even those areas that seemed most Hat, when seen through a telescope, to be covered by craters too small to be seen from the Earth.
The Soviet probe Luna IX succeeded in making a soft landing (one not involving the destruction of the object making the landing) on the moon on 3 February 1966 and sent back photographs from ground levels. On 3 April 1966, the Soviets placed Luna X in a three-hour orbit about the moon; it measured radioactivity from the lunar surface, and the pattern indicated the rocks of the lunar surface were similar to the basalt that underlies Earth’s oceans.
American rocketmen followed this lead with even more elaborate rocketry. The first American soft landing on the moon was that of Surveyor 1 on I June 1966. By September 1967, Surveyor 5 was handling and analyzing lunar soil under radio control from Earth. It did indeed prove to be basaltlike and to contain iron particles that were probably meteoric in origin.
On 10 August 1966, the first of the American Lunar Orbiter probes were sent circling around the moon. The Lunar Orbiters took detailed photographs of every part of the moon, so that its surface features everywhere (including the part forever hidden from Earth’s surface) came to be known in fine detail. In addition, startling photographs were taken of Earth as seen from the neighborhood of the moon.
The lunar craters, by the way, have been named for astronomers and other great men of the past. Since most of the names were given by the Italian astronomer Giovanni Battista Riccioli about 1650, it is the older astronomers—Copernicus, Tycho, and Kepler—as well as the Greek astronomers Aristotle, Archimedes, and Ptolemy, who are honored by the larger craters. The other side, first revealed by Lunik III, offered a new chance. The Russians, as was their right, pre-empted some of the more noticeable features. They named craters not only after Tsiolkovsky, the great prophet of space travel, but also after Lomonosov and Popov, two Russian chemists of the late eighteenth century. They have awarded craters to Western personalities, too, including Maxwell, Hertz, Edison, Pasteur, and the Curies, all of whom are mentioned in this book. One very fitting name placed on the other side of the moon is that of the French pioneer-writer of science fiction, Jules Verne.
In 1970, the other side of the moon was sufficiently well known to make it possible to name its features systematically. Under the leadership of the American astronomer Donald Howard Menzel, an international body assigned hundreds of names, honoring great men of the past who had contributed to the advance of science in one way or another. Very prominent craters were allotted to such Russians as Mendeleev (who first developed the periodic table that I will discuss in chapter 6) and Gagarin, who was the first man to be placed in orbit about Earth and who had since died in an airplane accident. Other prominent features were used to memorialize the Dutch astronomer Hertzsprung, the French mathematician Galois, the Italian physicist Fermi, the American mathematician Wiener, and the British physicist Cockcroft. In one restricted area, we can find Nernst, Roentgen, Lorentz, Moseley, Einstein, Bohr, and Dalton, all of great importance in the development of the atomic theory and subatomic structure.
Reflecting Menzel’s interest in science writing and science fiction is his just decision to allot a few craters to those who helped rouse the enthusiasm of an entire generation for space flight when orthodox science dismissed it as a chimera. For that reason, there is a crater honoring Hugo Gernsback, who published the first magazines in the United States devoted entirely to science fiction; and another to Willy Ley, who, of all writers, most indefatigably and accurately portrayed the victories and potentialities of rocketry.
And yet unmanned exploration of the moon, however dramatic and successful, is not enough. Could not human beings accompany the rockets? Indeed, it took only three and a half years after the launching of Sputnik 1 for the first step in this direction to be taken.
On 12 April 1961, the Soviet cosmonaut Yuri Alexeyevich Gagarin was launched into orbit and returned safely. Three months later, on 6 August, another Soviet cosmonaut, Gherman Stepanovich Titov, flew seventeen orbits before landing, spending 24 hours in free flight. On 20 February 1962, the United States put its first man in orbit when the astronaut John Herschel Glenn circled Earth 3 times. Since then dozens of men have left Earth and, in some cases, remained in space for months. A Soviet woman cosmonaut, Valentina V. Tereshkova, was launched on 16 June 1963 and remained in free flight for 71 hours, making 17 orbits altogether. In 1983, the astronaut Sally Ride became the first American woman to be placed in orbit.
Rockets have left Earth carrying two and three men at a time. The first such launching was that of the Soviet cosmonauts Vladimir M. Komarov, Konstantin P. Feokstistov, and Boris C. Yegorov, on 12 October 1964. The Americans launched Virgil I. Grissom and John W. Young in the first multimanned U.S. rocket on 23 March 1965.
The first man to leave his rocket ship in space was the Soviet cosmonaut Aleksei A. Leonov. who did so on 18 March 1965. This space walk was duplicated by the American astronaut Edward H. White on 3 June 1965.
Although most of the space “firsts” through 1965 had been made by the Soviets, the Americans thereafter went into the lead. Manned vehicles maneuvered in space, rendezvoused with each other, docked, and began to move farther and farther out. The space program, however, did not continue without tragedy. In January 1967, three American astronauts—Grissom, White, and Roger Chaffee—died on the ground in a fire that broke out in their space capsule during routine tests. Then, on 23 April 1967, Komarov died when his parachute fouled during re-entry. He was the first man to die in the course of a space flight.
The American plans to reach the moon by means of three-man vessels (the Apollo program) were delayed by the tragedy while the space capsules were redesigned for greater safety, but the plans were not abandoned. The first manned Apollo vehicle, Apollo 7, was launched on 11 October 1968, with its three-man crew under the command of Walter M. Schirm. Apollo 8, launched on 21 December 1968, under the command of Frank Borman, approached the moon, circling it at close quarters. Apollo 10, launched on 18 May 1969, also approached the moon, detached the lunar module, and sent it down to within nine miles of the lunar surface.
Finally, on 16 July 1969, Apollo 11 was launched under the command of Neil A. Armstrong. On 20 July, Armstrong was the first human
being to stand on the soil of another world.
Since then six other Apollo vehicles have been launched. Five of them—12, 14, 15, 16, and 17—completed their missions with outstanding success. Apollo 13 had trouble in space and was forced to return without landing on the moon, but did return safely without loss of life.
The Soviet space program has not yet included manned flights to the moon. However, on 12 September 1970, an unmanned vessel was fired to the moon. It soft-landed safely, gathered up specimens of soil and rock, then safely brought these back to Earth. Still later, an automatic Soviet vehicle landed on the moon and moved about under remote control for months, sending back data.
The most dramatic result obtained from studies on the moon rocks brought back by the landings on the moon, manned and unmanned, is that the moon seems to be totally dead. Its surface seems to have been exposed to great heat, for it is covered with glassy bits, which seem to imply the surface rock has been melted. No trace of any water has been found, nor any indication that water may exist under the surface or even did in the past. There is no life, and not even any sign of chemicals that may be related to life.
