How do sattelites/spacecrafts navigate and settle in space?

[brooklynspacecadet]

everyone sees on their televisions screens the nasa launches with the usual 5,4,3,2,1...<br />ok, but what happens once they leave the atmosphere and are in space?<br />how do they move around up there? how do they "put the brakes on"?<br />additionally how do those satellites up there just sit there in one place and not just float away into another universe?<br />what makes them stay put?

 

[vogon13]

Gravity, inertia, and Newton's 3 Laws of Motion..<br /><br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[nibb31]

They don't stay in one place. The ISS, the shuttle orbiter, or satellites orbit the earth. <br /><br />The rocket accelerates them to orbital velocity, which means that they escape earths gravity. Instead of falling back down to earth, their velocity allows them to stay in orbit. Basically, an orbit is a kind of free-fall where they are moving so fast that they keep on missing the earth. <br /><br />Their speed does not decay as it would in the atmosphere, because there is no air, therefore no friction, so once they reach the correct orbital velocity, they don't need their engines continuously. You only need to fire your engines to accelerate or decelerate, not to keep moving.<br /><br />The ISS and Atlantis are not just floating around in space, they are actually travelling very fast on an orbital trajectory.<br /><br />To return to earth, the shuttle orbiter has to turn around and fire its engines in the opposite direction to slow down, in order to fall back into the atmosphere.<br /><br />

 

[richalex]

Everything in space is moving around all the time, but they move in fairly predictable paths. For example, the Sun follows a predictable path across our sky, caused by the combination of Earth's rotation (day and night) and orbit (1 orbit around the Sun each year). The same rules apply to everything else in space. The space station is orbiting around Earth, just like our Moon is, but the space station is much closer to Earth and so has less distance to travel around Earth than Moon does. <br /><br />Gravity is the main controller of the paths that objects in space travel. Gravity pulls objects towards each other, but it is not a strong force. The bigger an object, the more it attracts other objects. Earth is fairly large, so Earth's gravity has a lot of influence on objects that are fairly close to Earth. <br /><br />Objects that orbit Earth must orbit on an imaginary sheet (called a "plane") that passes through the center of Earth's gravity, near the middle of the Earth. That means that we could not put a satellite into an orbit that only passes over the middle of the Northern Hemisphere, because that orbit would not be on a plane that passes through the middle of the Earth. <br /><br />Objects in orbit are falling down towards the middle of the Earth, but they are also speeding forward so fast that by they time they fall, they have passed over to the other side of Earth. If a rocket were to fly up to where the space station is, but remaining over the same spot where it took off without gaining speed across the Earth, it would quickly fall right back down to Earth when its engines stopped. That is known as a sub-orbital flight, because it never completes an orbit. <br /><br />I hope this answers some of your questions.