A rocket is a tube-like object, some shaped like a paper towel roll, that is sent flying into the air when its fuel is lit on fire. These tube-like objects come in many different shapes and sizes and have many different purposes. Hundreds of years ago, the ancient Chinese used rockets as weapons and fireworks. Only about 33 years ago, the first trip to the Moon in a rocket was successful. Now, rocket scientists are coming up with new and better rockets to explore space in the future.

The Beginning of Rockets

The Chinese invented the world’s first rockets around 1232 A.D. These rockets were basically painted tubes filled with an early form of gunpowder, that the ancient Chinese called "black powder". When the black powder in the rockets was ignited, it burst into flame. As a result, exhaust gas was generated. It exited from the bottom of the rockets, propelling them into the sky. The ancient Chinese called the rockets "arrows of flying fire" because the black powder burst into flame and sent the rocket flying into the air.

The Uses of Rockets

Rockets are useful in many ways. About 770 years ago in China, rockets were used in wars. They didn’t cause much damage, but they certainly frightened their enemies! The ancient Chinese also used rockets as fireworks. Rockets were more commonly used as fireworks than they were as military weapons in ancient China.

Today, rockets are used for many peaceful purposes. For example, they are used to carry payloads for commercial or scientific purposes into space. One of the most important commercial payloads are satellites, which are very important in our daily communication. Scientists use rockets to carry space probes into outer space to study other planets and objects in space. For example, the Viking spacecraft was used to send a Viking 2 Lander to Mars to send very important biological, chemical, and geological information back to the Earth.

Development of Spacecraft

People wanted to travel into space, but the fuel used in the ancient Chinese rockets burned and exploded too quickly. Obviously, scientists could not travel into space using a fuel that exploded or burned out in a few seconds. They had to find a fuel that would burn over a long period of time. Robert H. Goddard, an American scientist, experimented with different kinds of fuels and found that liquid fuel could supply the continuous source of energy that scientists were looking for.

Even though the use of liquid fuel would help to travel longer distances, there was still one problem left. Rockets could only carry a certain amount of fuel. When they ran out of fuel, they would give in to the Earth’s gravity and fall back to Earth. This, of course, was a very big problem until the Russian theorist, Konstantin Tsiolkovsky, invented the multistage rocket. A multistage rocket is a rocket made up of two of more vertically stacked sections. The bottom section takes the rocket up a certain distance and then detaches. The next section up then uses its fuel to move whatever is left of the rocket further up. If the rocket has more than two sections then the process continues until the rocket only has one section left, the very top of the rocket. Multistage rockets were used in the Mercury, Gemini, and Apollo programs.

The Mercury Program

In the Mercury program, the main goals were to send manned spacecrafts into orbit around the Earth, investigate human reaction to and abilities in space, and safely return the spacecraft and the astronaut to Earth. In the beginning of the Mercury project, the Mercury-Redstone 1, an unmanned test rocket, was launched to test the reliability of the emergency escape rocket at the tip of the main rocket.

After the next test flight, a 37-pound chimpanzee named Ham was sent on a suborbital flight in a Mercury rocket. He was brought back to Earth unharmed. Then, on May 5, 1961, Alan Shepard became the first American to be launched into space. During his 15-minute flight, he tested the control system and reported that everything worked well. Virgil "Gus" Grissom, the second man in space, flew successfully, but when he landed in the ocean, the hatch opened too soon and Gus almost drowned. Finally, on February 20, 1962, John Glenn was launched into space and orbited the Earth three times. He was the first American to orbit the Earth. The Mercury Project ended with another 3-orbit mission, a 6-orbit mission, and a 22-orbit mission.

The Gemini Program

The main goals of the Gemini program were to perfect the meetings and docking of spacecraft in space, to assure that man would not be permanently harmed when exposed to weightlessness for a long period of time, and to successfully demonstrate extravehicular activity (EVA). EVA is activity or maneuvers performed by an astronaut outside of a spacecraft in space.

The first piloted Gemini mission, two astronauts, Gus Grissom and John Young, orbited the earth three times. Five days before this, a Soviet cosmonaut was the first man to demonstrate EVA. 

Edward White, an American astronaut, soon reenacted this act on the 4-day, 62-orbit flight on June 3, 1965. He floated around in the weightlessness of space in a 31-pound space suit designed especially for EVA. He moved around in space firing a twin barreled gas gun. Imagine floating in space with a twin barreled gas gun at hand. You fire it in one direction, and you start floating the opposite way. This is how Edward White must have felt while being the first American to ever demonstrate EVA.

After the successful EVA, the U.S. launched the Gemini 5. This spacecraft orbited the Earth for a record breaking eight days. This Gemini mission proved that the spacecraft, Gemini 5, and the pilots, Leroy Cooper and Charles Conrad, could be exposed to weightlessness for eight whole days without suffering any long-term harm or damage. They also performed 17 scientific experiments and made detailed observations of Earth’s weather and ocean currents onboard the Gemini 5.

Now that two of the Gemini program’s goals were completed, there was only one left. The Gemini spacecraft had to rendezvous (meet) and dock with each other. The Gemini 6 and the Gemini 7 rendezvous was the first planned rendezvous, and it turned out to be the first accomplished rendezvous in the world.

Finally, the Gemini 8, with Neil Armstrong and David Scott on board, accomplished the world’s first docking in space. In this docking, something went wrong with the attitude thrusters (which are used to maneuver the spacecraft) and the Gemini 8 and the other joined vehicle started to spin wildly. When the Gemini 8 detached from the other spacecraft, it continued spinning, so the Gemini 8 had to make an emergency landing in the Pacific Ocean near Okinawa. The Gemini program achieved all of its main goals. NASA then moved onto a different space program, the Apollo program.

The Apollo Program

The main goal in the Apollo program was to land on the Moon. Using the technology that had developed from the prior programs, NASA used multistage rockets in the Apollo missions to attempt to land on the Moon. Using a multistage rocket, three astronauts would be sent in orbit around the moon in a Command Module. Then, two of the passengers would be detached from the Command Module in a landing craft, called the Lunar Module, while the other astronaut would stay in the Command Module. In this Lunar Module, the astronauts would land on the Moon’s surface and be free to walk outside of the spacecraft in space suits. On July 20, 1969, Neil Armstrong and "Buzz" Aldrin became the first people in the world to land on the Moon. As Neil Armstrong stepped down from the last step of the Lunar Module he made a statement. "That’s one small step for man…one giant leap for mankind." These words became very famous because they were the first words to come out of an astronaut’s mouth as his boot touched the motionless, gray dirt of the Earth’s Moon.

Rocket Engine and Fuel

There are two main types of rocket fuels, solid propellant and liquid propellant. Solid propellant engines have the simplest designs. They consist of cylinder casing, which is usually made of steel, filled with a mix of solid fuel and oxidizer with a channel of air running through the center of it. As you probably already know, oxygen is needed for anything to burn, but in space, there is no oxygen. How does the fuel burn? The fuel burns by using oxidizer, which provides the oxygen that is needed for it to burn. The fuel and oxidizer burn very fast, exhausting hot gas through the nozzle to produce thrust. When ignited, a solid propellant burns from the center out towards the sides of the casing. The center of the channel determines the speed and pattern of the burn, which determines how the rocket will be propelled. Unlike liquid propellant engines, solid propellant motors cannot be shut down. Once ignited, they will burn until all the propellant is exhausted.

In a liquid propellant rocket, the fuel and oxidizer are stored in separate tanks. They are sent through a system of pipes, valves, and turbopumps to a combustion chamber where they are combined and burned to produce thrust. By controlling the flow of propellant to the combustion chamber, the engine can be started, stopped, restarted, or throttled.

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