For this reason, they cannot operate in the vacuum of space. Unlike combustion or jet engines, rockets carry their own supply of oyxgen of other oxidizer with them. Just like the fuel, these can be in either solid, liquid, or hybrid form more on these later. The oxidizer and fuel are mixed in the rocket's combustion chamber and the exhaust gases are expelled at high speed from the rear of the rocket.
The process works both in the presence of an atmosphere and in the vacuum of space. The actual workings of the rocket usually take place in the absence of air -- in fact, unlike cars and airplanes, rockets do not have any air intakes. The molecules of the rocket's exhaust are individually very small, but they exit the rocket's nozzle very fast and in a large quantity giving them a great deal of momentum.
Enough, in fact, to provide a multi-ton object with the momentum it needs to escape Earth's gravity. Quite an impressive feat when you think about it. Thrust and lift are two of the fundamental forces of flight and, while related, they are distinctly different forces the other two fundamental forces being drag and weight.
The first, thrust, is any force that moves an aircraft or rocket in the direction of the motion. It can be created using a propeller, jet engine, or, of course, a rocket engine.
In the former two examples, the air is pulled in and then pushed out in an opposite direction -- much like a household fan. In the latter, no air is required to provide the vehicle's thrust. Lift, on the other hand, is the careful interaction of aerodynamic forces that keep airplanes, or similar vehicles, in the air. For aircraft, providing lift is the main job of the wings and other lift surfaces. For rockets, lift is less of an important consideration, as its trajectory and "flight" are more a factor of its propulsion and trajectory of flight as considerations for overcoming drag tend to take precedence.
That being said, lift is important for the stabilization and control of the rocket during flight and is usually provided by the fins, nose cone, and body tube. Most modern rockets consist of at least two stages.
These are sections of the rocket that are stacked one on top of each other in a cylindrical shell aka serial staging. Other types of rockets use parallel staging. In this case, smaller first stages are strapped to the body of a central "sustainer" rocket.
At launch, all of the engines are ignited. When the propellants in the strap-on rockets are extinguished, they are discarded while the sustainer engine continues burning. Each stage has its own set of engines, which vary in number depending on the design. For example, the first stage of SpaceX's Falcon 9 has nine engines, whereas Northrop Grumman's Antares rocket has two.
The job of the first stage is to get the rocket out of the lower atmosphere. There may or may not be extra side boosters to help out, too. Because this initial stage must carry the weight of the entire rocket with payload and unspent fuel , it is usually the biggest and most powerful section. As the rocket accelerates, it initially encounters an increase in air resistance -- which it must also overcome through brute thrust. To save on money when shooting for far-away planets such as Jupiter, some spacecraft whip around a planet say, Venus and use its gravity to get a speed boost.
This shortens the time it takes to get to other destinations. Follow LiveScience on Twitter livescience. Live Science. Suborbital rockets such as Blue Origin's New Shepard are strong enough to temporarily enter space, either for scientific experiments or space tourism.
Orbital-class rockets are powerful enough to launch objects into orbit around Earth. Depending on how big the payload is, they also can send objects beyond Earth, such as scientific probes or sports cars. Ferrying satellites to orbit or beyond requires serious power. For a satellite to remain in a circular orbit miles above Earth's surface, it must be accelerated to more than 16, miles an hour. The Saturn V rocket, the most powerful ever built, lifted more than , pounds of payload into low-Earth orbit during the Apollo missions.
As some rocket makers go big, others are going small to service the growing boom in cheap-to-build satellites no bigger than refrigerators. Rocket Labs's Electron rocket can lift just a few hundred pounds into low-Earth orbit, but for the small satellites it's ferrying, that's all the power it needs. A launch pad is a platform from which a rocket is launched, and they're found at facilities called launch complexes or spaceports. Explore a map of the world's active spaceports.
A typical launch pad consists of a pad and a launch mount, a metal structure that supports the upright rocket before it launches. Umbilical cables from the launch mount provide the rocket with power, cooling liquids, and top-up propellant before launch.
The structure also helps shield the rocket from lightning strikes. Different launch complexes have different ways of putting rockets on launch pads. At NASA's Kennedy Space Center, the space shuttle was assembled vertically and moved to the launch pad on a tank-like vehicle called a crawler. The Russian space program transports its rockets horizontally by train to the launch pad, where they're then lifted upright. Launch pads also have features that minimize damage from the rocket's launch.
When a rocket first ignites, valves lining the launch pad spray hundreds of thousands of gallons of water into the air around the exhaust, which helps lessen the rocket's deafening roar. Trenches beneath the launch pad also direct the rocket's exhaust out and away from the craft, so the flames can't rise back up and engulf the rocket itself. There are many launch sites around the world, each with different pros and cons. In general, the closer a launch site is to the Equator, the more efficient it is.
That's because the Equator moves faster than Earth's poles as the planet rotates, like the outer edge of a spinning record. Launch sites at higher latitudes more easily place satellites into orbits that pass over the poles. Between and , 29 spaceports sent satellites or humans into orbit. Many of the sites are still active, including the only three facilities ever to launch humans into orbit.
More spaceports are on the way, both public and private. In , the U. The European Space Agency's spaceport in French Guiana is open to visitors , but the agency encourages travelers to plan ahead. Tourists can visit Kazakhstan's Baikonur Cosmodrome, the storied home of the Soviet and Russian space programs, but only by booking a tour. The facility remains closely guarded. See pictures of the villages near Russia's Plesetsk Cosmodrome, where salvaging discarded rockets is a way of life.
If you can't visit a spaceport in person, never fear: Many public space agencies and private companies offer online livestreams of their launches. All rights reserved. How do rockets work?
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