The Basics of Rocketry
Everyone knows the term "rocket." Putting aside ballads, basketball and dance troupes, what do we actually mean when we say something is a rocket? In fact, "rocket" can refer to two things: a rocket engine or an object powered by a rocket engine.
A rocket engine differs from other engines — such as jet engines — because it produces thrust using only substances from within. It doesn't draw in outside oxygen to create thrust, as jet engines do, and this gives rocket engines the unique ability to keep right on working in an oxygen-free environment, like outer space. Most rocket engines are chemical, meaning they use propellants (usually fuel and an oxidizer) to create a chemical reaction that produces thrust.
Rockets can range from those simple enough to construct at home to rockets complex enough to put humans into orbit. But they all rely on the same basic "rocket science," and they're all a product of a long and amazing rocket history.
Rockets That Go Boom
Rocket technology has been finding its way into weapons for centuries, going back to 1232 when the Chinese attached rudimentary rockets to arrows and used them to ward off Mongol invaders during the battle of Kai-Keng. Fast-forward a few centuries and America's national anthem, "The Star Spangled Banner," references the "rockets' red glare," a nod to British rockets launched during the War of 1812. In more recent history, Germany bombed London with rockets during World War II.
These days, rockets continue to play a prominent role in warfare. The military uses them primarily to power things like missiles, which wouldn't get very far without the thrust from a rocket (or other) engine. Rockets also allow military personnel to fire explosives from great distances, far from enemy lines or sometimes at enemy aircraft. But rockets have a place in closer combat, as well. A rocket-propelled grenade (RPG), for example, is a handheld rocket launcher that is fired from the shoulder and often used to target armored vehicles.
The idea of rockets as weapons dates back ages, but scientific exploration trumps destruction in newer applications for rocket engines.
Rockets That Go Zoom
Since the middle of the 20th century, the unique ability of rocket engines to operate without oxygen has made them the power behind manned and unmanned flights into space. Without rockets, it wouldn't have been possible to launch probes, satellites, shuttles or human beings into orbit. The iconic moment when Neil Armstrong took his first step on the moon would never have happened without rockets. Scientists also use rockets for atmospheric research, and these "sounding" or meteorological rockets help us learn more about weather patterns and the Earth's atmosphere. And, of course, rockets continue to make their mark on pop culture through fictional heroes like "Iron Man," who relies on rocket-powered boots to fly in his massive armor.
Perhaps the best-loved and most entertaining kind of rocket remains one that has been around for thousands of years -- fireworks. These rockets are still making people look up to the skies in wonder and probably will be for centuries to come.