Satellites???

Question

Why don't satellites crash into Earth?

Answer 1

centrifugal (center seeking) force.

Satellites in orbit must reach a balance between the earth's gravitational pull and the satellite's own escape velocity. When those two forces are equal, the satellite doesn't get closer or farther away from the earth.

Objects in low orbit must travel faster than objects in high orbit. This is because the gravitational pull from the earth is stronger the closer you get to it, and the satellite will need a higher velocity to counter the pull.

It is the canceling of these two forces that make any object in orbit seem weightless.

Answer 2

Eventually, without adjustments, they do. The atmosphere of Earth gets gradually thinner and thinner but there's no outer boundary to it. If there is are enough molecules of gas in the way, they will exert a drag on a satellite, slowing it down. This is important because speed is the key to staying in orbit.

Every rocket launch trajectory is an elipse. Powered flight sends the payload up faster than the acceleration of gravity. When the power stops, gravity takes full control, the payload slows, stops, and falls, accelerating toward the ground. If it's straight up, you can't see the arc of the trajectory, but if it's angled, you'll see a parabolic arc (an elipse, if the Earth wasn't in the way). The more power applied to the launch, the larger the arc and the farther downrange the payload lands.

If the rocket has enough power, the landing point moves beyond the edge of the Earth. This is effectively an orbit. Gravity is still pulling the rocket toward the Earth, but the rocket's speed is high enough that it continually misses the Earth. You can't maintain the speed without more power because of the drag of air. But if you get high enough that the air is too thin to interfere, you can maintain the orbit with almost no additional power.

The minimum orbit is about 100 miles up, although there is still a slight drag. 150 miles up, where the shuttle orbits, is pretty stable. 200 miles up is space station territory. The higher up you are, the more energy it took to get you there and the faster you have to be going, but the easier it is to stay there.

When a shuttle or a Soyuz returns to Earth, it first fires rockets into the direction of its travel. These act as a brake, slowing the spacecraft down, making its arc shorter and beginning its re-entry.

Answer 3

They are in orbit, just like the Moon. If you don't understand what keeps the Moon from crashing into Earth, you won't understand how satellites stay up either.

Answer 4

So long as they maintain enough velocity to stay in orbit, they won't. But when they slow down enough, they eventually do, but they're pretty small and they burn up on reentry. Some are larger, like SkyLab, and actually do crash (in that case, in Australia, I think).

Answer 5

when earth see a satelite i hide on the back of the sun