Rockets or rocket-powered vehicles are used to send a spacecraft in space or beyond Earth’s atmosphere. These spacecrafts could be sent either into any orbit around our Earth or in any other place in outer space. Such rocket-powered vehicles have been used since the 1950s for various purposes – to send manned spacecraft in space or in different celestial bodies or to send unmanned space probes and satellites into space. A rocket must accelerate to a minimum speed of 28,000 km per hour to reach Earth’s orbit and the fuel used for rockets helps to achieve it. This speed is approximately 25 times the speed of sound.
What is the Fuel for Rockets?
Launch vehicles need energy to send the spacecraft into outer space. This energy is required in the form of fuel, which is used to power rocket launchers. These fuels can be divided into two major groups- liquid fuels and solid fuels.
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Liquid Fuels
Various types of Liquid fuels are used in rockets. Some of them are very easily available such as kerosene. It can be used at ground temperature. Liquid hydrogen is also used as a fuel in rockets. It is also known as “cryogenic” fuel and must be maintained at the extremely low temperature of 20 K.
Hypergolic is another type of fuel for rockets or rocket propellant. It spontaneously ignites when it comes into contact with an oxidizer. These fuels are extremely lethal and harmful for any kind of living beings. Thus, these are very difficult to manage.
Solid Fuels
Solid fuels are usually very simple in design. They are like big fireworks. These types of fuels consist of a casing which is filled with a rubbery mixture of solid compounds. These compounds generally burn very quickly when they are ignited. Solid fuels are actually some organic material or powdered aluminum. Ammonium perchlorate is used as the oxidizer in most cases.
When these materials are mixed, the rocket propellant is formed. When the solid rocket engines are ignited, they start to burn their fuel until it is completely exhausted. Once ignited, they cannot be turned off. When the fuel burns in the rocket engine, the flow of exhaust gases comes out through a nozzle at the bottom of the launch vehicle. These nozzles are used to shape and accelerate the flow of exhaust gases so that it can provide a forward thrust and the launch vehicle can take off.
How does Rocket Launching work?
The fundamental working principle of a rocket is based on Newton’s third law of motion, which states that “For every action, there is an equal and opposite reaction”. In case of rockets, the “action” is the rapid flow of exhaust gases from the rear of the vehicle. It is produced by the combustion of the fuel used in the vehicle in its rocket engine.
Here, the “reaction” is the pressure, which is applied to the internal structure of the rocket. It is also called thrust which pushes the vehicle in the opposite direction of the flow of exhaust gases. Rockets usually carry their own oxidizing agent so that when they leave Earth’s atmosphere, they can operate in the vacuum of the outer space.
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How many stages does a Rocket have?
Konstantin Tsiolkovsky, a Russian rocket scientist, first suggested the basic procedure to launch a rocket into outer space. He suggested that the best way to launch the vehicle is to separate it into different stages.
First Stage
The first stage of a rocket consists of the largest rocket engines, massive fuel and oxidizer tanks, and also maximum thrust. The primary function of this stage is to impart the initial thrust which is needed to overcome the gravity of our Earth. It also carries the entire weight of the vehicle and its payload.
When the propellants of the first-stage are completely used, it is detached from the other parts of the rocket to reduce the weight of the launch vehicle. After that, it falls back to Earth – either into the ocean or in a very less populated area. Thus, no living beings is harmed in this process.
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Second Stage
After the removal of the first stage, the rocket engines and propellants continue to increase the speed of the vehicle in the second stage. Most of the expendable rocket launchers have maximum two or three stages. To achieve orbital velocity, some rocket launchers had up to five stages in earlier times.
When the mission of the second stage is completed, it also gets separated from the other parts of the launchers and falls back to Earth. In some cases, this part breaks apart and evaporates when it falls back towards Earth due to the atmospheric heating. Sometimes, this stage also enters the orbit.
Upper Stages
All rocket launchers or launch vehicles usually have more than one stage to accelerate the spacecraft and to achieve the orbital velocity. Since the orbital launch of the first artificial satellite Sputnik in 1957, there have been many different upper stages used in launch vehicles.
Most of these are used only as a part of the rocket launcher. Nowadays, to launch more modern technology, improvements and modifications in the construction of these upper stages are going on. The main objective is to increase the overall lift capability of the rocket launcher, reduce the costs of the mission and increase its reliability.
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What is a Space Elevator and How does it work?
According to many rocket scientists, chemically fueled rocket propulsion is the best way to lift any object out of Earth’s gravity. Konstantin Tsiolkovsky first suggested the concept of a space elevator in 1895. This arrangement consists of a tremendously strong cable which extends from the surface of Earth to the height of geostationary orbit or beyond.
The forces of gravity acts towards the lower end of cable and outward centripetal acceleration acts at the other end. These two forces, acting on the opposite direction, keeps the cable under tension. It also helps the cable to remain still over a single location on Earth. However, this concept can only be applied after serious preliminary research.