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ETpro's avatar

Is it time to develop a crashing satellite defense system for the whole Earth?

Asked by ETpro (34247 points ) October 24th, 2011

First it was Skylab. Pieces the size of a kitchen range and weighing several hundred pounds were expected to make it intact to the ground. But where? We never really found out. Now a multi-ton satellite of the German Space Agency has crashed. It came down over the weekend somewhere, with chunks likely as big as a refrigerator and weighing a ton making it to the ground. But it’s not clear where it crashed. Two major cites in China, both with 1 million plus populations, were in the danger zone but fortunately, both were spared.

We have movies like Enemy of the State in which satellite surveillance can track an individual everywhere they go and even pan around to stare in their face or read the wristwatch on their arm. But reality is obviously vastly more crude than Hollywood movies suggest. With more and more space junk decaying in orbit and crashing to the Earth, sooner or later there is going to be a collision where significant numbers of human beings are injured and killed. And we can’t predict where that calamity will occur till after the fact.

I understand the degree to which chaos theory influences the final trajectory of a falling satellite. If we ever get to the point where we can accurately predict ground zero, it may take decades. It’s possible we will never reach that point. The exact decay trajectory may prove to be stochastic. If our rocket science, physics, math and Earth sciences mavens want to explain the prediction difficulties in answering, feel free.

But given that we can’t predict where to play heads up, isn’t it time we develop a tracking and defense system capable of blowing these things up while they are high enough in orbit that the debris will just burn up on reentry? It might prove handy to defend against comets and asteroids as well.

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11 Answers

mazingerz88's avatar

Either that or each new satellite could maybe have self-destruction capability or thrust feature where it could maneuver itself to be captured by Earth’s gravity then plunge into an ocean or a desert.

El_Cadejo's avatar

I’ve also thought about this quite a bit myself. Great question.

Though I must say this is worthless against asteroids. Ya see if that were to happen what we’d have to do is send a group of humans up there to plant a bomb on the asteroid and blow it up in space. :P

Hibernate's avatar

I believe so.

njnyjobs's avatar

@uberbatman… that concept has been thought of and made into a movie, Armageddon

ratboy's avatar

I suspect the probability of death or injury from raining space junk is very much smaller than the probability of death or injury from, say, errant automobiles. I would devote the resources to something more pressing. Anyway, there is a degree of coolness to being killed by a gizmo from outer space.

RocketGuy's avatar

I would agree with @ratboy – probability of getting hit by space junk is much lower than probability of being hit by a car.

I think nowadays, satellite designers are planning in fuel for de-orbit into the ocean. You don’t want to blow anything up while in orbit because the pieces would stay in orbit until they hit something (probably important).

njnyjobs's avatar

^^ how can you doubt that coming from someone named RocketGuy..?

ETpro's avatar

@uberbatman I was just thinking of a back up plan to deal with asteroids if Bruce Willis happens to be tied up on locatoni filming another blockbuster hit when the object approaches Earth.

@ratboy It would be a super-cool way to punch your ticket, but the downside is you’d never get to enjoy the glow.

@RocketGuy That’s probably more cost effective than deploying a defense system, but doesn’t address comets or asteroids.

Isn’t anybody going to explain why it is so incredibly difficult to predict where a satellite will crash?

RocketGuy's avatar

Air resistance is a function of the orientation of the satellite. Head first, and it goes further. Bellyflop and it goes shorter. If it tumbles an unknown rate, you don’t know how many minutes of head first and how many of belly forward. Thus you can’t tell where it will land.

El_Cadejo's avatar

@njnyjobs yes, I know… that was the point :P

ETpro's avatar

@RocketGuy It’s even much more complex than that. The Earth isn’t a perfect sphere. The height of an atmosphere at equilibrium would therefore vary as the satellite’s path varied. Add to that the fact the atmosphere is nowhere near equilibrium. It’s a seething mass of high and low pressure systems constantly swirling and moving about. Thus the density of the atmosphere at a constant altitude varies from almost nonexistent to relatively high. Even actively navigating a satellite to a predictable splashdown is challenging.

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