Although rockets are widely viewed as ultra-modern inventions, the principles behind them have been at least generally understood for thousands of years. The first mechanical devices that might be thought of as rockets were developed as steam-driven curiosities in Greece around the fourth century B.C. By the first century A.D. the Chinese had formulated an early type of gunpowder and were rolling it into tight paper tubes that could propel an arrow or other missile. The rocket was born.
In theory, the rocket is a fairly simple proposition. It is a vehicle that carries some type of fuel internally. The fuel is caused to expand (usually by way of some chemical reaction, such as ignition) and the exhaust from this expansion is forced out through a small opening at the rear. Forward momentum is simply the equal-but-opposite reaction to this exhaust. The mighty Saturn V rocket and the humble balloon that is released with being tied closed, both move about by virtue of the same physical forces.
For centuries, rocketry changed little. Most of the innovations that did occur came about from attempts to deploy rockets as offensive weapons. One common type was a crude rocket rigged to explode on impact, and stabilized in flight somewhat by being tethered to a stick. The British Navy employed rockets of this type as shore-bombardment weapons, and it was their use against Fort McHenry during the War of 1812 that inspired Francis Scott Key (1779-1843) to write his famous line about "the rockets' red glare."
Rocketry took a great leap forward in the early twentieth century, largely thanks to the work of the American scientist Robert H. Goddard (1882-1945). Goddard built the first liquid-fuel rocket and was the first to realize that rockets would operate more efficiently in the vacuum of space.
It was during World War II, though, that modern rocketry developed. The German military had become interested in the possibilities that rockets offered, and sponsored much research and development during the years leading up to the war. The Versailles Treaty that ended World War I forbade Germany from building an air force, and rocketry was seen as one way of circumventing the prohibition. After the war began on September 1, 1939, the Reich poured vast resources into the rocket program. Wernher von Braun (1912-1977) was the brilliant young rocket scientist who directed much of the research. By 1944, Germany had developed and were using dozens of different types of offensive rockets; everything from surface-to-air missiles to anti-personnel weapons. Most famous, though, was von Braun's A-4 rocket, more commonly known as the V-2.
The V-2 was deployed as Hitler's great "vengeance weapon" against the people of England. Launched from mobile bases in Western Europe, the rockets could carry a thousand-pound warhead all the way to London in just minutes. The V-2 was a guided missile, carrying gyroscopes coupled to steering vanes that directed it to its target. Since the re-entry phase of the rocket's flight was supersonic, there was no way for the British to stop it. The British people suffered hundreds of V-2 attacks until advancing Allied armies swept German forces out of launching range. Although the V-2 caused much destruction and loss of life, it was not very effective as a strategic weapon. The Germans were never able to deploy them in the numbers needed to impair the Allies' war efforts. Still, as a harbinger of coming technology, the V-2 was an amazing achievement, and may very well have been the first man-made object to travel beyond the stratosphere.
After the war, von Braun and many of his colleagues relocated to the United States to help develop the American rocket program. One of their first successes was the Redstone missile, which was designed as both an offensive weapon and as the space vehicle used in NASA's Mercury launches. Later they built the multi-stage Saturn rocket, still one of the largest ever constructed, that carried American astronauts to the Moon. Multi-stage rockets allow fuel (usually a combination of liquid hydrogen and oxygen) to be burned quickly during the early stages of the rocket's flight. This helps the rocket develop a very high velocity within a few seconds of its launch, and helps it reach escape velocity--a speed high enough to leave the earth's immediate gravitational field.
Rocketry today is a very well-understood science, thanks to the work of pioneers like Goddard and von Braun. Modern solid- and liquid-fueled rockets have become reasonably safe and dependable vehicle platforms, used by both science and commerce in applications ranging from powering the space shuttle to placing telecommunication satellites in orbit. Tiny solid-fuel rocket motors even power one of the most popular contemporary hobbies: model rocketry. Advances continue to the present day that make rocketry both more accessible and more commonplace.
This is the complete article, containing 789 words
(approx. 3 pages at 300 words per page).
