Nuclear Winter

[kochman]

For use to lose several at once from space debris seems incredibly unlikely... doesn't it?

 

[capnvonbaron]

I am not 100% sure about this (I can't exactly go and check it myself) but I think in deep space objects even the size of a grain of sand are pretty rare.

Well, at highway speeds, a bug splatting on the windshield is going to expel what little kinetic energy it has (12mg housefly @ 30m/s = .0054 J) in perhaps a thousandth of a second. At speeds above even 1% c, that energy is all going to be expelled almost instantaneously, in the realm of a trillionth of a second or less. So if you want to make a spaceship with a hull that can withstand the force of a ton of TNT exploding on it, be my guest. Just hope it doesn't hit more than a couple of particles. God forbid it hit something even softball sized.

PoM has a valid point... I've seen a figure that says if you took a 1 cm diameter sample of all the matter between here and the Vega star system, asssuming you didn't pick up any stray particular matter, the amount you'd pick up wouldn't even fill the eye of a needle. But you do have to remember that you're going to be spending a good deal of time accellerating through the Kuiper belt and Oort cloud (the latter extends nearly a quarter of the distance to Proxima Centauri) where particulate matter is really not that rare in interstellar space terms. It would be safe to assume that the Alpha Centauri system would have something similar surrounding it, so you will be spending over half the journey in non-interstellar medium. I think its a valid thing to worry about.

 

[BrainEater5000]

For use to lose several at once from space debris seems incredibly unlikely... doesn't it?

Sure, I'm just speculating that space junk is going to increase in quantity and increase the rare chance of this happening, but then again, it's probably never going to cause any sort of havoc because surely there are several redundant satellites. So, what I'm trying to say is, never mind.

 

[kochman]

So, I see you are still working on that formula despite no proof that it would really hold up under such extreme circumstances, I see.

Anyhow, I don't buy it. I don't by that a particle of dust would seriously damage such a huge spaceship at such speed... I think it would just do what a bug does...
splat... That's my belief, and I am stickin' with it until more than a (untested at these levels) math formula stands against me.

 

[Willem]

Losing enough communication satellites would create panic and danger here on earth.

It's not just the disruption on Earth but the cost of losing a multi-million dollar satellite. If space junk gets to the point where this is a common-place event, it doesn't become very cost-effective to put stuff in orbit. And once a satellite becomes disabled, then it becomes nothing more than space junk itself, compounding the problem.

 

[Willem]

Anyhow, I don't buy it. I don't by that a particle of dust would seriously damage such a huge spaceship at such speed... I think it would just do what a bug does...
splat... That's my belief, and I am stickin' with it until more than a (untested at these levels) math formula stands against me.

A couple of quotes from this article: http://en.wikipedia.org/wiki/Space_debris

The sudden increase in debris load led to a re-evaluation of the debris issue and today a catastrophic impact with large debris is considered to be the #1 threat to Shuttle operations on every mission.Mission planning now requires a throughout discussion of debris risk, requiring an executive level decision to proceed if the risk is greater than 1 in 200 of destroying the Shuttle. On a normal low-orbit mission to the ISS the risks are estimated to be 1 in 300, but the STS-125 mission to repair the Hubble Space Telescope at 350 miles was initially calculated at 1 in 185 due to the 2009 satellite collision, and threatened to cancel the mission.

If the Kessler Syndrome comes to pass, the threat to manned missions may be too great to contemplate operations in LEO. Although the majority of manned space activies take place at altitudes below the critical 800 to 1,500 kilometres (310 mi) regions, a cascade within these areas would result in a constant rain down into the lower altitudes as well. The time scale of their decay is such that "the resulting debris environment is likely to be too hostile for future space use."

They're discussing ships that are travelling at only orbital velocity being destoyed or disabled. The problem becomes much worse if you're travelling at 10% the speed of light. If you want to close your eyes to what is a well known problem with space travel, that's your business.

 

[kochman]

Brute force and ignorance have solved a lot of problems that science hasn't... so, sure, I will close my eyes to the theory discussed on Wikipedia.

 

[capnvonbaron]

Anyhow, I don't buy it. I don't by that a particle of dust would seriously damage such a huge spaceship at such speed... I think it would just do what a bug does...
splat...

So, if you accelerated the HMS Titanic up to 10% lightspeed, and it plowed into the iceberg, it would simply *splat* the iceberg and not sink?

Sounds fair to me

 

[kochman]

That argument is flawed on so many levels, here are 3... come on... I know you were being tongue in cheek (at least, I hope), but let's be real here.

1) size of objects... particle of dust vs huge spaceship... versus titanic versus iceberg? Not really close to the same thing
2) density of objects is still not considered... particle of dust vs huge spaceship that can travel through atmospheres and at 10% of light speed? compared to ice rock vs ship hull.
3) Titanic was terribly flawed in its construction, it could have survived had it been constructed properly, as I would hope a huge spaceship would be

 

[Willem]

Brute force and ignorance have solved a lot of problems that science hasn't... so, sure, I will close my eyes to the theory discussed on Wikipedia.

Are you always this blind? If NASA specialists consider it a problem are you simply going to dispute their concern? And even if a small particle doesn't destroy an inter-planetary ship out right, we're dealing with a voyage that will take 44 years out in space, being hit by who knows how many particles. That will be alot of wear and tear on a ship to the point that it might end up being destroyed or disabled. Nothing in space lasts that long. Even the shuttles are a little over twenty years old and they're being mothballed soon, with constant maintenance after each flight. If a ship that's light years from the nearest repair facility starts running into problems because of constant particle impacts, there's not much that the crew can do about it, except bend over and kiss their ass goodbye.

 

[BrainEater5000]

It's not just the disruption on Earth but the cost of losing a multi-million dollar satellite. If space junk gets to the point where this is a common-place event, it doesn't become very cost-effective to put stuff in orbit. And once a satellite becomes disabled, then it becomes nothing more than space junk itself, compounding the problem.

Good point.

 

[kochman]

Are you always this blind? If NASA specialists consider it a problem are you simply going to dispute their concern? And even if a small particle doesn't destroy an inter-planetary ship out right, we're dealing with a voyage that will take 44 years out in space, being hit by who knows how many particles. That will be alot of wear and tear on a ship to the point that it might end up being destroyed or disabled. Nothing in space lasts that long. Even the shuttles are a little over twenty years old and they're being mothballed soon, with constant maintenance after each flight. If a ship that's light years from the nearest repair facility starts running into problems because of constant particle impacts, there's not much that the crew can do about it, except bend over and kiss their ass goodbye.

Getting a little snippy are we? Lighten up, Francis...
You are using wikipedia as your source, when I question your source used regarding a theory, you are surprised? Get over it.
I don't buy into a lot of the theories that people push as though they were facts, even NASA. Sorry... global warming being manmade is one that springs immediately to mind. I don't anything on blind faith because NASA scientists say so... prove it.
This statement may flabbergast some of you... but scientific theory (which is all this is) is wrong a lot... often proved to be wrong by the scientific method.
Anyhow, because you are clearly starting to take this personally, I will drop out of this conversation, ignorance blissfully intact. Thank you very much!

 

[TheMeInTeam]

Well, at highway speeds, a bug splatting on the windshield is going to expel what little kinetic energy it has (12mg housefly @ 30m/s = .0054 J) in perhaps a thousandth of a second. At speeds above even 1% c, that energy is all going to be expelled almost instantaneously, in the realm of a trillionth of a second or less. So if you want to make a spaceship with a hull that can withstand the force of a ton of TNT exploding on it, be my guest. Just hope it doesn't hit more than a couple of particles. God forbid it hit something even softball sized.

PoM has a valid point... I've seen a figure that says if you took a 1 cm diameter sample of all the matter between here and the Vega star system, asssuming you didn't pick up any stray particular matter, the amount you'd pick up wouldn't even fill the eye of a needle. But you do have to remember that you're going to be spending a good deal of time accellerating through the Kuiper belt and Oort cloud (the latter extends nearly a quarter of the distance to Proxima Centauri) where particulate matter is really not that rare in interstellar space terms. It would be safe to assume that the Alpha Centauri system would have something similar surrounding it, so you will be spending over half the journey in non-interstellar medium. I think its a valid thing to worry about.

These #'s aren't QUITE right. First of all, it's not quite the same as exploding TNT...the energy involved is certainly comparable but the particle itself will not explode...and the ship probably wouldn't either (why would the item not tunnel? And how deeply would it tunnel in X thickness of material?). The alternative I could picture is like hitting something that would effectively cause a huge indent/hole as the material gave to the force, or maybe like hitting a wall.

This also assumes ramming something head on rather than at an angle which for the larger objects at least would be significant.

Then again at truly high speeds length contraction would probably factor to negate that...though ships traveling at those speeds would have to be designed first before that mattered .

For a trip like that how does time dilation factor in if you get very near the speed of light? I could have said it about 7-8 years ago, but it's been a long time since that physics class. My understanding, however, is that if people could actually accelerate to near-light speeds that time would essentially slow down for them (er...relative to time on earth)?

 

[Willem]

I don't buy into a lot of the theories that people push as though they were facts, even NASA.

Then you believe nothing except what you yourself can prove, which means you believe in nothing at all. For everything eventually boils down to a theory at some point. You've taken cynicism to a whole new level, and there's really no point in you engaging in any sort of discussion. Nothing is true after all.

 

[kochman]

Then you believe nothing except what you yourself can prove, which means you believe in nothing at all.

Wow, you extrapilated that out of what I said?
You are something else there willem, getting snippier and snippier... did you just plug my words into a trusty formula? Or was it a wikipedia article that told you that?
Goodness... Sorry that I believe in things like statistical significance and the scientific method. From now on, I will pass all my thoughts by your first for screening before posting

 

[Willem]

Wow, you extrapilated that out of what I said?

Hmm, let's see. The Theory of Evolution, the Theory of Gravity. I guess the world didn't exist until you were miraculously created and you don't go flying off into space because of magic. Your very perception of reality is nothing but a theory. You don't actually see the objects around you, you merely see the light reflecting from them. You extrapolate their form from what your limited perception allows you to. You can't be absolutely certain that's actually what they look like though. That's nothing but a theory that you've created.

 

[kochman]

And snippier, and snippier...

 

[Willem]

And snippier, and snippier...

No, I'm just trying to point out your absurd logic.

 

[Ghpstage]

Interesting...
I wonder if that equation holds up at such extreme numbers. Is it not possible that it wouldn't?
Anyhow, I guess we are a long way from proving that one... unless there is some study you know of... I don't know much about this stuff, admittedly. It seems hard to swallow that surface toughness/density are not considered at all by the equation...

I think you have misunderstood what this equation actually means and its significance. The kinetic energy equition 1/2MV^2 only gives an objects KE (which obviously doesn't cover all of an impacts properties). The significant part however is that if you double the speed you quadruple the energy as opposed to doubling energy when you doube its mass .

You are also quite right that it doesn't hold up at astronomical speeds, there you need to take relativity into account if you want accuracy. Though I doubt it will make a huge difference to someone merely looking to understand how big a problem it is.

A couple of vids that may explain how its a problem better. Involving squishy birds and aircraft, not to disimilar to your fly on the windshield argument.
757 engine destroyed
Airbus wing damage (with a bit of blood )
C-130 damage from a birdstrike (shows the dead bird )
Bear in mind that these collisions are happening at low speeds during take-off or landing as typically aircraft won't meet any birds at its cruising altitude.

2) density of objects is still not considered... particle of dust vs huge spaceship that can travel through atmospheres and at 10% of light speed? compared to ice rock vs ship hull.

When you want to look at the actual damage inflicted you need to see how that energy changes on impact which will involve heat transfer, structural deformation, velocity changes and quite a few other things. Also if you want to think about density, consider that the energy already calculated was for a mass of very small size, the energy density would be tremendous!

If you actually wanted to come close to making a decent estimation of the effects of impact you would need specialised computer software

 

[6K Man]

Any particles in front of the speeding spaceship will be picked up by the ramscoop. The more, the better.