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A satellite in orbit around the Earth does not fall into the Earth because the force of Gravity between the satellite and Earth is exactly balanced by the centripetal reaction force of the satellite constantly changing direction.

Think of driving in a car in a straight line. Now, think about turning right. You will be pulled towards the left. Well, actually, you are going in a straight line and the car is moving to the right. That causes you to drift towards the left. You encounter the door, and now you are going to the right as well. The door is pushing on you towards the right, and you are pushing towards the left against the door. The force pushing you towards the right is sort of like Gravity, while the force you are pushing on the door to the left is your centripetal reaction force. Since you are going in a constant speed circle, these two forces are balanced. Its the same type of thing as a satellite.

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13y ago
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12y ago

Satellites in orbit around Earth are travelling at very high speeds. Gravity makes them continually fall toward Earth, but because Earth is curved they travel around it.

The force the satellite experiences is a force that could be described as centripetal, or towards the center of the satellite's orbit. Assuming the satellite is a geostationary satellite, or that it maintains its orbit at relatively the same spot to the earth, this becomes a very simple idea of balancing forces.

A satellite experiences a force Fg, or the force due to gravity. This force can be calculated by the equation:

Fg = G*(ME*MS)/(ro)2

Where G is the gravitational constant, ME is the mass of the Earth, MS is the mass of the satellite, and rois the radius of orbit (from the Earth's center).

Since this force is centripetal, we can set this equal to:

Fc = MS*v2/ro

Where v is the velocity of the satellite.

When you set this equal, you can solve for the velocity necessary to keep a geostationary satellite in orbit as a function of the height of the orbit.

G*(ME*MS)/(ro)2 = MS*v2/ro

(G*ME/ro).5 = v

Since G and ME are constants, the relationship can be simplified to:

v = (C/ro).5

This shows that the velocity needed to keep a satellite in orbit is inversely proportional to the square of the radius of orbit. Perhaps the most fascinating thing about this is that the mass of the satellite has no effect. (They simply require more energy to reach orbit.)

Falling Satellites

Satellites can eventually fall out of orbit, either due to some slight friction with the atmosphere (that slows them down), or because their orbits become otherwise unstable. Many will use manuevering (or station-keeping) rockets, small rocket engines attached to them that can be fired to keep their orbits stable.

In the long term, we accept that satellites cannot be economically kept in orbit, and design them to have a limited lifespan. That is, we look at the satellite's proposed orbit, and, taking into account the amount of fuel that the on-board station-keeping rockets will have, calculate the maximum amount of time that the orbit can be maintained. This is the maximum operational lifespan of the satellite, and the rest of the on-board components are design to last just slightly longer than this.

In other words, Planned Obsolesence - the satellite stops working just before it falls out of orbit.

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12y ago

Satellites actually are falling back to Earth, but because they are travelling so fast around the the globe - they keep on missing. It's this balance of speed that also stops them from floating away.

Imagine a person holding a ball on a piece of string. If the person spins too fast the tension on the string will increase and the ball will want to fly off. If the person doesn't spin fast enough the ball is going to keep falling back to the person when released. But if the person spins at just the right speed they can maintain a balance in between the two.

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12y ago

The vast majority of man-made satellites orbiting the earth will indeed eventually have their orbit decay and fall back into the earth's atmosphere.

However, many of the satellites in a geosynchronous orbit or beyond (including several in highly eccentric orbits) will not fall back to earth - instead they will either fall towards the Moon, or, in most cases, simply exit the Earth-Moon system and wander the Solar System.

The exact fate of a specific satellite depends entirely on its orbit at the time it runs out of maneuvering fuel and can make no more adjustments; it then is totally at the mercy of gravitational force.

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15y ago

In a perfect vacuum, a satellite will remain in orbit indefinatly, but space contains dust and gasses, and colliding with these will gradually slow it down and cause it to lose altitude.

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16y ago

A satellite has to maintain a constant velocity of 8000 m/s in order to stay in Earth's orbit. If it gains mass or slows down at all, it will fall back into Earth's atmosphere.

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15y ago

the satellite is throne in orbit with such a specific speed that centrifugal force on it is balanced by centripital force due to gravity on it so it becomes stable...

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12y ago

They usually burn up in the atmosphere. occasionally they are large enough that pieces hit the ground.

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Q: What happens when artificial satellites fall back to earth?
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What happens to old satellites?

Old satellites orbiting near the Earth eventually fall back into the atmosphere and burn. Satellites orbiting farther away stay in orbit indefinitely.


Does Venus have any satellites?

No. Venus has no natural satellites (moons). Neither does Mercury.


What are examples of solar satellites?

In one sense all the planets are solar satellites, that is, they orbit the sun, just as the moon is Earth's satellite. So Mars, Venus, Earth and all the planets are solar satellites.In another sense a solar satellite could be any of Earth's artificial satellites, because most of them use solar panels to generate the electricity they need to keep sending data back to Earth.


What force acts to pull natural and artificial satellites to earth?

Gravity. A natural satellite aka asteroid, then meteor, then meteorite all get pulled to Earth through gravity. With artificial sattelites it's tge same thing, gravity. The difference is we launch our satellites to the perfect zone around the planet where they become trapped in orbit around us. Sometimes things occur that bump these satellites out of their orbit and gravity takes over, pulling the satellite back to the surface.


What were satellites originally made for?

The first artificial satellite that had a particular purpose (other than just for scientific research) was the Echo satellite; a large mylar balloon placed in orbit to reflect radio signals back to the Earth. Now, satellites are used for all kinds of communications; TV, cell phones, overseas phone calls, internet and such; weather satellites that help to predict the weather and track storms, and reconnaissance satellites that take photos of the Earth. Oh; GPS satellites.


What were Echo 1 and Telstar 1?

Communications satellites, launched in the 1960's. There were 2 Echo satellites, which were passive (the signal would bounce back to earth like a mirror). The Telstar satellites were active, meaning that the signal was retransmitted back to earth.


Who invent the world is round?

The earth is a spherical shape, and they food this out because in the late 20th century, artificial satellites sent back pictures confirming the earths round shape. Much earlier, Aristotle suspected earth was a sphere by observing that earth cast a curves shadow on the moon during an eclipse.


How do satellites get the weather?

Satellites take pictures and accumulate other information into the computer. They analyze the data and send it back to weather stations on earth.


How was the satellite invented?

The idea of an artificial satellite goes back at least as far as the prototype science fiction story "The Brick Moon". The idea that actual, real satellites could perform useful work goes back to about 1947, when science fiction author Arthur C. Clarke realized that satellites orbiting the equator at about 22,000 miles out, would appear not to move in the sky. You could aim an antenna at it and leave it. Thus you could make communications satellites that could transmit a signal from anywhere on Earth to anywhere on Earth, just by having 3 satellites spaced around the Earth. The first actual, real satellite was Sputnik, sent up by the Russians in the late Fifties.


How many satellites are moving around earth?

One big, natural satellite has been in orbit 4.5 billion years. We call it "the moon." There are about 180 man made satellites in geosynchronous orbit. More are added every few years. In low earth orbit there are about 3000, at the present time. Older ones tend to fall back to earth, but new ones are added every few months. The first artificial satellite was launched by the Russians in 1957.


What do GPS satellites do?

GPS satellites orbit the earth, around 20,000Kms above us. They contain very precise atomic clocks which they use to produce a special timing signal which is then broadcast back to earth. Back on earth, we can use our GPS receivers (Like Sat Nav) to pick up the GPS signals, and by using very clever mathematical algorithms in conjunction with the timing signals we receive from the satellites, calculate our position on the surface of the earth.


How do satellites fall back to Earth?

That will happen if they lose movement energy - usually due to atmospheric drag, if they are not high enough above Earth.