Beyond: Our Future in Space (4 page)

Rather than becoming China’s first astronaut, Wan Hu was probably obliterated from the explosive force of so many rockets detonating simultaneously. Despite this spectacular failure, the Middle Kingdom was far ahead of other countries in developing rockets, beginning a long tradition that twinned rocketry with warfare.

The earliest uses of rockets are poorly documented. There are reports that the Greek philosopher Archytas, who speculated about the edge of space, amused the citizens of Tarentum in southern Italy by moving a wooden bird through the air suspended on wires. The propulsion mechanism was escaping steam. The first true rockets were probably accidents. In the first century AD, the Chinese learned how to make simple gunpowder from saltpeter, sulfur, and charcoal dust.
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They put this mixture into bamboo tubes and tossed them into a fire to make explosions during religious festivals. Some of the tubes may have failed to explode, instead skittering out of the fire propelled by gas from the burning gunpowder.

The word
rocket
appears as early as the third century, during the Three Kingdoms period. Soldiers had learned to attach bamboo tubes filled with gunpowder to arrows, light them, and then launch them with bows. In 228, the Wei State used this kind of “fire arrow” to defend the city of Chencang from the invading forces of the Shu State.

Over the next few centuries, rockets continued to appear in harmless fireworks celebrations, but they showed more promise as military weaponry. The Chinese discovered how to make rockets that could launch themselves. A tube holding gunpowder was capped at one end, with space for a slow-burning fuse, and the other end was left open. The tube was attached to a stick to provide stability and a crude guidance system. When ignited, the outrushing gas from this solid-fuel rocket produced a large forward thrust. Such rockets were first used in battle by the Chinese in 1232 to repel Mongol invaders.
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Although they weren’t effective as weapons of destruction, one can only imagine the psychological effect of being on the receiving end of a barrage of “arrows of flying fire.”

Soon, other cultures began their own experimentation and implementation. The Mongols adopted rockets and hired Chinese rocket experts as mercenaries, who helped them conquer Russia and parts of Europe. They used rockets to capture Baghdad in 1258. Quick to learn, the Arabs used rockets ten years later to help defeat Louis IX of France between the Seventh and Eighth Crusades. Europeans soon learned its secrets and started to improve the technology.
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Roger Bacon discovered the optimum formula for gunpowder: 75 percent saltpeter, 15 percent carbon, and 10 percent sulfur. This recipe was more explosive than Chinese recipes and gave rockets greater range.

Early rockets were so unreliable they could only be used to confuse and frighten the enemy. As the chemistry of gunpowder matured, however, rockets began to influence the outcome of battles. It was the world’s first arms race.

The Chinese continued to create new and complex rockets throughout the Ming Dynasty, when even a great seafaring nation like China suffered many thefts and losses due to piracy. To fight the pirates, General Qi Jiguang used hardwood for the body of the rocket and had armor-piercing swords or spears at the front end. He put more than 2,000 rockets on ten warships and developed multishot rockets that allowed up to a hundred of the devices to be launched simultaneously with a single fuse. Other innovations were multistage rockets that could fly for several miles over water and rockets with reusable tubes. General Qi used all of these methods to defend the Great Wall from the Mongols.

The Chinese were first to develop gunpowder and rockets, and during medieval times they were able to keep invaders at bay with formidable arsenals, but their science was based on experimentation with no corresponding development of theory. In the late thirteenth century, mathematician Yang Hui noted: “The men of old changed the name of their methods from problem to problem, so that as no specific explanation was given, there is no way of telling their theoretical origin or basis.”
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Ironically, the stability of Chinese civilization worked against innovation. With a strong central government and stifling bureaucracy, there was little incentive to try something new. Europe, meanwhile, suffered a series of famines and plagues that put an end to growth and caused social upheaval. The Renaissance and the Scientific Revolution emerged from this chaos and propelled Europe to great prosperity.

Ultimately, neglect of science and technology caused the Chinese to lose their edge. By the late fourteenth century, Europe had caught up. For warfare, Europeans developed and perfected the smooth-bore cannon. Rockets were relegated to firework displays.
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Wan Hu’s dreams of traveling to the stars were forgotten.

They were given a firm theoretical basis in the work of Isaac Newton, the author of a theory of gravity and laws of motion that would be the basis for space travel centuries later. Newton’s 1687 masterwork,
Principia
, unified the terrestrial and celestial realms. Drop an apple and it falls in one second 3,600 times farther than the Moon curves in its orbit, both caused by the action of the Earth’s gravity. He described a “thought experiment” where a cannon points sideways at the top of a mountain high enough to be above the atmosphere. With no friction or air resistance, the only force operating is gravity.
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Fired at modest speed, the cannonball will land at the base of the mountain. As the initial speed is increased, the ball travels farther and farther before landing. Newton calculated the speed where the ball falls toward the Earth’s surface at the same rate as the Earth’s surface is “falling away” from it (
Figure 5
).

This is the concept of an orbit. Any projectile shot from Newton’s hypothetical cannon at 7.9 kilometers per second or 17,650 mph would remain a captive of the Earth’s gravity but would never hit the ground. At over 11 kilometers per second or just over 25,000 mph, the projectile would be liberated from the Earth forever.

The Visionaries

Konstantin Eduardovich Tsiolkovsky was an unlikely rocket scientist. In 1857, he was born into an impoverished family of Polish immigrants in a small Russian town, the fifth of eighteen children. At the age of ten, he developed scarlet fever, leaving him deaf and isolated. By the age of fourteen, his mother had died and he had given up formal schooling.

A reclusive teenager, he moved to Moscow so he could spend long hours at a local library, where he studied physics and astronomy. At the library he was influenced by Nikolai Fyodorov, a futurist who advocated radical life extension and immortality and who thought that the future of humanity lay in space. He also stumbled on the works of Jules Verne and became inspired by Verne’s tales of space travel. Tsiolkovsky’s family recognized his talent but worried that he was studying obsessively and forgetting to eat. When he was nineteen, his father brought him back home and helped him get a teaching credential so he could earn a living.

Tsiolkovsky became a math teacher in a small provincial school outside Moscow. In his spare time he wrote science fiction, but soon he became more interested in the concrete problems of space travel. He realized that passengers would not survive the acceleration forces of a cannon, the method Jules Verne imagined to get travelers to the Moon. He was far from any center of learning, so when he tried to publish his work on the kinetic theory of gases, a friend had to point out that those ideas had been published twenty-five years earlier. Even as a teenager, Tsiolkovsky had constructed a centrifuge to test the effects of strong gravity. Chickens procured from local farmers were his test subjects. Later, he built the world’s first wind tunnel in his apartment and conducted experiments on the aerodynamics of spheres, disks, cylinders, and cones. But he had no funding for his research and he was isolated from the scientific community, so most of his insights were theoretical.

In 1897, however, Tsiolkovsky had an insight that underlies all of space travel today.

He devised an equation relating the change in mass of a rocket to its exhaust velocity. He recognized the critical role of a nozzle in forcing the gas out at high velocity, and he predicted the need for multistage rockets to overcome the Earth’s gravity. He also designed fins and gas jets to control the trajectory, pumps to drive fuel into the combustion chamber, and mechanisms that used propellant to cool the rocket in flight. His fertile mind came up with designs for dirigibles, metal jet aircraft, and hovercraft. Hearing about the newly constructed Eiffel Tower triggered the idea of a space elevator as a way of getting into orbit without a rocket.
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This Russian visionary continued to face adversity.
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A year before he developed the rocket equation that bears his name, Tsiolkovsky’s son committed suicide. Eight years later, a flood destroyed most of his papers. Three years after that, his daughter was arrested for engaging in revolutionary activities.

In 1911 he wrote: “To place one’s feet on the soil of asteroids, to lift a stone from the moon with your hand, to construct moving stations in ether space, to organize inhabited rings around Earth, Moon and Sun, to observe Mars at the distance of several tens of miles, to descend to its satellites or even to its own surface—what could be more insane!”
¹¹
His work took all these ideas from unreal fantasy to the brink of reality.

Tsiolkovsky was sustained in his work by a philosophical and spiritual movement called cosmism. In Russia, one of the foremost proponents of cosmism was Nikolai Fyodorov, whom Tsiolkovsky had met at the library. They shared a utopian belief that the future of humanity was to spread into space and conquer disease and death. Cosmism emerged after the Russian Revolution, envisaging a heroic image of the proletarian who strides forth from the Earth to conquer planets and stars.
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One quote epitomizes Tsiolkovsky’s views on space: “The Earth is the cradle of humanity, but mankind cannot stay in the cradle forever.”

In the 1920s, the young physicist Hermann Oberth was unaware of Tsiolkovsky’s work, but he too dreamt of space travel. Like the Russian, Oberth was inspired by Jules Verne, rereading the novels to the point of memorization. He dabbled with rockets as a child and by 1917 his expertise had grown such that he fired a rocket with liquid propellant as a demonstration for the Prussian minister of war.
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His doctoral thesis, “The Rockets to the Planets in Space,” later became an essential contribution to rocket science, but initially it was rejected. Oberth was fiercely critical of the German education system, saying it was “. . . like an automobile which has strong rear lights, brightly illuminating the past. But looking forward, things are barely discernible.”
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Like Tsiolkovsky, Oberth worked outside academia for the majority of his career, earning a living as a schoolteacher. He was a leading member of the “Spaceflight Society,” a German amateur rocketry group whose members scavenged any materials they could find for their rockets as Europe descended into an economic depression. In 1929, Oberth was a technical adviser to the film pioneer Fritz Lang for
Woman in the Moon
, the first film ever to have scenes set in space. He lost an eye during a publicity stunt for the film. That same year, he conducted a captive firing of his first liquid-fueled rocket engine. One of his assistants was eighteen-year-old Wernher von Braun, who would later feature prominently in our efforts to reach space.