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? What are the stages of a rocket launch?
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.
Many spacecraft and satellites travel no further than this low Earth orbit LEO , but those destined to leave Earth entirely and explore the wider solar system need a further boost in speed to reach escape velocity — the speed at which they can never be pulled back by our planet's gravity.
The escape velocity at Earth's surface — 6. It gets lower at a greater distance from Earth, and probes bound for interplanetary space are often first injected into elongated or elliptical orbits by a carefully timed burst of thrust from an upper-stage rocket, which may remain attached to the spacecraft for the rest of its interplanetary flight.
In such an orbit the spacecrafts' distance from Earth can range from hundreds to thousands of miles, and its velocity will also vary, reaching a maximum when the spacecraft is closest to Earth — a point called perigee — and slowing down further out.
Surprisingly, however, the critical rocket burn used to escape into interplanetary space is usually made when the spacecraft is near perigee. This is due to the so-called Oberth effect , an unexpected property of rocket equations that means a rocket is more efficient when it is moving at higher velocity.
One way to understand this is that burning a spacecraft's fuel allows the engine to utilize not only its chemical energy, but also its kinetic energy, which is greater at higher speeds. On balance, the additional rocket thrust needed to reach escape velocity from a low altitude at higher speed is less than that needed to escape from a high altitude when moving at a lower speed.
Spaceflight engineers and mission planners often refer to the " Delta-v " required to accomplish a specific flight maneuver, such as a change in orbit.
Strictly speaking, the term Delta-v means change in velocity, but engineers use it specifically as a measure of the amount of impulse, or thrust force over time, needed to accomplish a maneuver. Broadly speaking, missions are planned around a "Delta-v budget" — how much thrust they can generate for how long using the spacecraft's onboard fuel supplies. Sending a spacecraft from one planet to another with minimum Delta-v requirements involves injecting it into an elliptical orbit around the sun, called a Hohmann transfer orbit.
The spacecraft travels along a segment of the elliptical path that resembles a spiral track between the orbits of the two planets, and requires no further thrust along its journey. On arrival at its target object it may use gravity alone to enter its final orbit, or it may require a burst of rocket thrust in the opposite direction — usually accomplished by simply turning the spacecraft around in space and firing the motor — before it can achieve a stable orbit.
Join our Space Forums to keep talking space on the latest missions, night sky and more! 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. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. 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. A shotgun is shooting about an ounce of metal in one direction at about miles per hour, and your shoulder gets hit with the reaction. If you were wearing roller skates or standing on a skateboard when you shot the gun, then the gun would be acting like a rocket engine and you would react by rolling in the opposite direction.
If you have ever seen a big fire hose spraying water, you may have noticed that it takes a lot of strength to hold the hose sometimes you will see two or three firefighters holding the hose. The hose is acting like a rocket engine. The hose is throwing water in one direction, and the firefighters are using their strength and weight to counteract the reaction. If they were to let go of the hose, it would thrash around with tremendous force.
If the firefighters were all standing on skateboards, the hose would propel them backward at great speed! When you blow up a balloon and let it go so that it flies all over the room before running out of air, you have created a rocket engine.
In this case, what is being thrown is the air molecules inside the balloon. Many people believe that air molecules don't weigh anything, but they do see the page on helium to get a better picture of the weight of air. When you throw them out the nozzle of a balloon, the rest of the balloon reacts in the opposite direction. More on Rocket Engines. Photo courtesy NASA. Thrust " ". Solid-fuel Rockets: Fuel Mixture " ". Solid-fuel Rockets: Channel Configuration " ". The propellant mixture in each SRB motor consists of an ammonium perchlorate oxidizer, The propellant is an point star-shaped perforation in the forward motor segment and a double- truncated- cone perforation in each of the aft segments and aft closure.
This configuration provides high thrust at ignition and then reduces the thrust by approximately a third 50 seconds after lift-off to prevent overstressing the vehicle during maximum dynamic pressure. Simplicity Low cost Safety. Thrust cannot be controlled.
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