Why would a communications satellite fall out of the sky? Fact and conjecture wanted.?

Question

There are lots of satellites circling the earth. I'm wondering, do they have a "life span" before they start to fall. Could they all be made to fail at once, and by what, and if they did fail, would they bombard the earth or burn up in the atmosphere? A screenplay depends upon the right answer.

Answer 1

All satellites in orbit are continuously dropping due to atmospheric drag. It's a very small effect that adds up over time so typically satellites will use their propulsion systems to recover the lost speed to maintain their orbit. If they would all start a quick fall at once something would have to slow them down quickly all at once which I can't think of anything that would do that naturally. As for reentry only the larger satellites on the order of tons won't burn up completely. So large communication satellites and space station like structures will survive. An example of this are the Skylab space stations of the 1970's. For a more technically answer if would depend on the speed and angle of reentry.

Answer 2

I don't know what the right answer is for your screenplay but most com sats are in synchronous orbit at about 30000 km they are there to stay. I would image an EXTREMELY fluky hit by a meteor at exactly the right vector MIGHT be able to drop a com sat on earth.
Low Earth Orbit (LEO) satellites do have a life time and would be a better bet. The ISS loses a few km per month between boosts by the shuttle and during a solar maximum the atmosphere heats up and rises putting more LEO sats in danger.
good luck with your screenplay
cheers

Answer 3

Well, the net force on it is not zero, gravity is acting on a satellite, albeit the forces are very small in value. A satellite is not beyond the pull of Earth's gravity. Technically, nothing in the universe is beyond the pull of any object's gravity, its just that the gravitational force of an object weakens as you get further away from it. A satellite is in Earth's gravitational field, but that's not why it doesn't fall out of the sky. A satellite is being pulled the gravitational forces of the sun and other planets as well as Earth, but those forces are so small that they're practically negligible. EDIT: Actually, the guy below me is correct, it'd be 4, None of the above... I forgot geosynchronous orbit just means an object in orbit matches the Earth's rotational period, but a satellite doesn't have to be in geosynchronous orbit to stay in orbit. So yeah, since A thru E can all be argued against, it's gotta be None of these.

Answer 4

When satellites are no longer useful or cannot be repaired, they eventually are shut off and fall from orbit.

A satellite remains in orbit until its velocity decreases and gravitational force pulls it down into a relatively dense part of the atmosphere. A satellite slows down due to occasional impact with air molecules in the upper atmosphere and the gentle pressure of the sun's energy. When the gravitational force pulls the satellite down far enough into the atmosphere, the satellite rapidly compresses the air in front of it. This air becomes so hot that most or all of the satellite burns up.

Answer 5

Hmmm creativity and hypothetical reasons to bring down satellites...

How about the magnetic pole swap? It is theorized that the north/south magnetic poles will switch places relatively soon. Maybe during the swap, gravity will lessen a small amount, just enough to let the atmosphere expand a little bit and cause drag on low earth orbit satellites (more than they were designed to handle) bringing them all crashing down at once. Since the atmosphere would be less dense they wouldn't completely burn up and could smash into major cities world wide.

Ooo I'd watch that (:

Answer 6

Communication satellites in geostationary orbit cannot fall because they are in such high orbits. Satellites in lower orbits can fall after a few years because they are orbiting in the thin upper atmosphere and so experience a tiny amount of drag. That drag causes the satellites to very gradually spiral down until they enter the denser parts of the atmosphere and fall to the ground or vaporize in the upper atmosphere from the fierce heating cause by the increasing drag in the denser air.

Answer 7

Hey, Baldmike. How many hypotheticals you want us to consider all at the same time?

A Mass Coronal Ejection (MCE) of the magnitude that was experienced in 1859 is generally viewed to be a potential satellite "killer", though most of the newer models can "button up" and survive the radiation. Anything presently Earth-generated would be far too puny and localized (like all-out nuclear war) to affect the satellites themselves.

I'm afraid that the Earth-orbits vary from geosynchronous (23,000 miles up) to low Earth orbits (200 to 300 miles up), many of those polar orbits. I cannot imagine even the MCE event as being strong enough to "knock down" satellites. That would be quite a stretch. I promise to do more research and put you on a contact list.

While I'm thinking about it, a Shoemaker-Levy 9 event on Earth or Mars, even, is far more plausible, and dovetails right in with all those people I refer to as "Chicken Littles". There were 21 chunks of that comet hitting Jupiter. Your scenario might change to Mars and a well-developed colony.

Answer 8

Most communication satellites are in geosynchronous orbits, 21,700 miles high. At they distance, air drag is practically nonexistent. Their orbits do not decay appreciably for decades, and it would take a century or more for them to fall back into the atmosphere and burn up. Pieces of a really big one might reach the ground.

The iridium satellites, on the other hand orbit at 485 miles above the ground. Air drag at that height is significant, requiring occasion boost from a small rocket. Still, it would take years for one of them to reenter the atmosphere after running out of fuel. The most likely scenario for one of them to fall ahead of schedule would be a computer glitch causing its rocket to fire in the wrong direction and fail to shut down.

Answer 9

There is no perfect orbit that a body can maintain that will last forever.

When something is in orbit around another body, it is really just in a state of freefall around it. It is constantly falling toward the surface but is also traveling fast enough to keep from falling onto the surface.

Manmade sattellites all have a limited lifespan. Their orbits are continually decaying and will fall SOON (relatively speaking) unless more boost is given.

The Moon, however is GRADUALLY pulling away from the earth at a rate of mere centimeters a year.

Answer 10

Yes, depending on the altitude of their orbit and their velocity. The only way to make them fall all at once would be if they all had the same altitude and velocity and yes they would depending on their mass burn up in the atmosphere, maybe a few very small pieces would make it through.............gravity would eventually pull them all down