Why rockets work

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. But, as it moves higher, the atmosphere becomes thinner and the air resistance lessens. This means that the stress experienced by the rocket during a typical launch rises initially, to a peak and then falls back down.

The peak pressure is known as max q. For the SpaceX Falcon 9 and the United Launch Alliance Atlas V , max q is usually experienced at between 80 and 90 seconds of a launch, at an altitude of between seven miles 11 km to nine miles Once the first stage has completed its duty, rockets usually drop that section and ignite their second stage.

The second stage has less work to do because it has less mass to move and has the advantage of having a thinner atmosphere to contend with. For this reason, the second stage often only consists of a single engine.

Most rockets will also jettison their fairings at this stage too this is a pointed cap at the rocket's tip that protects the payload. In the past, discarded lower sections of the rocket would simply burn up in the atmosphere.

But starting around the earlys, engineers began designing these sections to be recoverable and reusable. Depending on the profile of this gap, which may be circular or star-shape, for instance, the amount of exposed surface will change during the flight.

This article is brought to you by All About Space. All About Space magazine takes you on an awe-inspiring journey through our solar system and beyond, from the amazing technology and spacecraft that enables humanity to venture into orbit, to the complexities of space science. The more widespread liquid-fueled rockets are far more complex. Typically, they involve a pair of propellant tanks — one each for the fuel and the oxidant — connected to a combustion chamber through a complex maze of pipes.

High-speed turbopumps driven by their own independent motor systems are used to deliver liquid propellant into the chamber through an injection system. The rate of supply can be throttled up or down depending on requirement, and fuel can be injected as a simple jet or a fine spray. Inside the combustion chamber an ignition mechanism is used to begin combustion — this may be a jet of high-temperature gas, an electric spark or a pyrotechnic explosion.

The detailed design of a liquid rocket stage can vary a lot depending on its fuel and other requirements. Some of the most efficient propellants are liquefied gases such as liquid hydrogen , which is only stable at very low temperatures — around minus degrees Fahrenheit minus degrees Celsius. Once loaded aboard the rocket, these cryogenic propellants must be stored in heavily insulated tanks.

Some rockets avoid the need for an ignition mechanism using hypergolic propellants that ignite spontaneously on contact with each other.

Rockets are the key to exploring our solar system , but how do they go from orbit to deep space? The first stage of any spaceflight involves launch from Earth's surface into a relatively low orbit around miles km up, above the vast majority of the atmosphere. Here gravity is almost as strong as it is on the surface, but friction from Earth's upper atmosphere is very low, so if the uppermost stage of the rocket is moving fast enough it can maintain a stable, circular or elliptical trajectory where the pull of gravity and the vehicle's natural tendency to fly off in a straight line cancel each other out.

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? What are the stages of a rocket launch? Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets.

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Environment Planet Possible India bets its energy future on solar—in ways both small and big. Environment As the EU targets emissions cuts, this country has a coal problem. In , Robert Goddard tested the first liquid-propellant rocket engine.

His engine used gasoline and liquid oxygen. He also worked on and solved a number of fundamental problems in rocket engine design, including pumping mechanisms, cooling strategies and steering arrangements. These problems are what make liquid-propellant rockets so complicated. The basic idea is simple. In most liquid-propellant rocket engines, a fuel and an oxidizer for example, gasoline and liquid oxygen are pumped into a combustion chamber.

There they burn to create a high-pressure and high-velocity stream of hot gases. These gases flow through a nozzle that accelerates them further 5, to 10, mph exit velocities being typical , and then they leave the engine.

The following highly simplified diagram shows you the basic components. This diagram does not show the actual complexities of a typical engine see some of the links at the bottom of the page for good images and descriptions of real engines. For example, it is normal for either the fuel or the oxidizer to be a cold liquefied gas like liquid hydrogen or liquid oxygen.

One of the big problems in a liquid-propellant rocket engine is cooling the combustion chamber and nozzle, so the cryogenic liquids are first circulated around the super-heated parts to cool them. The pumps have to generate extremely high pressures in order to overcome the pressure that the burning fuel creates in the combustion chamber. The main engines in the Space Shuttle actually use two pumping stages and burn fuel to drive the second stage pumps.

All of this pumping and cooling makes a typical liquid propellant engine look more like a plumbing project gone haywire than anything else -- look at the engines on this page to see what I mean.

We are accustomed to seeing chemical rocket engines that burn their fuel to generate thrust. There are many other ways to generate thrust however. Any system that throws mass would do. If you could figure out a way to accelerate baseballs to extremely high speeds, you would have a viable rocket engine.

The only problem with such an approach would be the baseball "exhaust" high-speed baseballs at that left streaming through space. This small problem causes rocket engine designers to favor gases for the exhaust product. Many rocket engines are very small. For example, attitude thrusters on satellites don't need to produce much thrust. One common engine design found on satellites uses no "fuel" at all -- pressurized nitrogen thrusters simply blow nitrogen gas from a tank through a nozzle.

Thrusters like these kept Skylab in orbit, and are also used on the shuttle's manned maneuvering system. New engine designs are trying to find ways to accelerate ions or atomic particles to extremely high speeds to create thrust more efficiently. See this page for additional discussion of plasma and ion engines.

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Mobile Newsletter chat subscribe. Space Transportation Systems. How Rocket Engines Work. HowStuffWorks See more rocket pictures. The vacuum of space Heat management problems The difficulty of re-entry Orbital mechanics Micrometeorites and space debris Cosmic and solar radiation The logistics of having restroom facilities in a weightless environment.

If you have ever shot a shotgun , especially a big gauge shotgun, then you know that it has a lot of "kick. That kick is a reaction.