So on Earth , the acceleration of gravity is 32 feet per second per second 21 mph per second. If you were floating in space with a bag of baseballs and you threw one baseball per second away from you at 21 mph, your baseballs would be generating the equivalent of 1 pound of thrust. If you were to throw the baseballs instead at 42 mph, then you would be generating 2 pounds of thrust.
If you throw them at 2, mph perhaps by shooting them out of some sort of baseball gun , then you are generating pounds of thrust, and so on. One of the funny problems rockets have is that the objects that the engine wants to throw actually weigh something, and the rocket has to carry that weight around.
So let's say that you want to generate pounds of thrust for an hour by throwing one baseball every second at a speed of 2, mph. That means that you have to start with 3, 1-pound baseballs there are 3, seconds in an hour , or 3, pounds of baseballs. Since you only weigh pounds in your spacesuit , you can see that the weight of your "fuel" dwarfs the weight of the payload you. In fact, the fuel weights 36 times more than the payload.
And that is very common. That is why you have to have a huge rocket to get a tiny person into space right now -- you have to carry a lot of fuel.
You can see the weight equation very clearly on the Space Shuttle. If you have ever seen the Space Shuttle launch, you know that there are three parts:. The Orbiter weighs , pounds empty.
The external tank weighs 78, pounds empty. The two solid rocket boosters weigh , pounds empty each. But then you have to load in the fuel. Each SRB holds 1. The external tank holds , gallons of liquid oxygen 1,, pounds and , gallons of liquid hydrogen , pounds.
The whole vehicle -- shuttle, external tank, solid rocket booster casings and all the fuel -- has a total weight of 4. To be fair, the orbiter can also carry a 65,pound payload up to 15 x 60 feet in size , but it is still a big difference.
All of that fuel is being thrown out the back of the Space Shuttle at a speed of perhaps 6, mph typical rocket exhaust velocities for chemical rockets range between 5, and 10, mph. The SRBs burn for about two minutes and generate about 3. The three main engines which use the fuel in the external tank burn for about eight minutes, generating , pounds of thrust each during the burn.
Solid-fuel rocket engines were the first engines created by man. They were invented hundreds of years ago in China and have been used widely since then. The line about "the rocket's red glare" in the national anthem written in the early 's is talking about small military solid-fuel rockets used to deliver bombs or incendiary devices.
So you can see that rockets have been in use quite awhile. The idea behind a simple solid-fuel rocket is straightforward. What you want to do is create something that burns very quickly but does not explode.
As you are probably aware, gunpowder explodes. In a rocket engine, you don't want an explosion -- you would like the power released more evenly over a period of time. In this case, instead of gunpowder, you get a simple rocket fuel.
This sort of mix will burn very rapidly, but it does not explode if loaded properly. Here's a typical cross section:. On the left you see the rocket before ignition. The solid fuel is shown in green. It is cylindrical, with a tube drilled down the middle. When you light the fuel, it burns along the wall of the tube. Liquid forms of fuel tend to be classified as petroleum like kerosene , cryogens like liquid hydrogen , or hypergolics like hydrazine. In some cases, alcohol, hydrogen peroxide, or nitrous oxides can also be used.
Solid propellants tend to come in two forms: homogenous and composite. Both are very dense, stable at room temp and are easily stored. The former can be either a simple base like nitrocellulose or a double base like a mixture of nitrocellulose and nitroglycerine. Composite solid propellants, on the other hand, use a crystallized or finely ground mineral salt as the oxidizer. In most cases, the actual fuel tends to be aluminum-based.
The fuel and oxidizer may be held together with a polymeric binder that is also consumed during combustion. Launchpads, as the name suggests, are platforms from which rockets are launched. They tend to form part of a larger complex, facility, or spaceport. A typical launchpad will consist of a pad or launch mount, which will usually be a metal structure that supports the rocket in an upright position prior to blastoff. These structures will have umbilical cables that fuel the rocket and provide coolant prior to launch, amongst other functions.
They will also tend to have lightning rods to protect the rocket during lightning storms. Launch complexes will vary in design, depending on the rocket's design and the operator's needs. For example, the NASA Kennedy Space Center designed the Space Shuttle to attach vertically to a rocket and was moved to the launch pad on a massive tank-like vehicle called a " Crawler.
In Russia, rockets were assembled and transported horizontally to the launch pad before being lifted upright in situ. And that, rocket fans, is your lot for today. While this introduction has been pretty brief, it should equip you with the basic tidbits of knowledge you'll need to gain a basic appreciation for these amazing pieces of technology.
There are plenty of resources out there to learn more, and we thoroughly recommend you check them out at your own leisure. By subscribing, you agree to our Terms of Use and Privacy Policy. You may unsubscribe at any time. By Christopher McFadden.
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.
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.
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