Meteoroid speeds and interstellar travel

[Venom]

At 42:00 of this video, the guy says that alien technology that crossed the cosmos would be able to withstand an attack by nuclear warheads because micro-meteoroids in space would do far more damage at the speed their spacecraft would be travelling in.

Would a pebble sized meteoroid be able to slam into a spacecraft traveling, say, a tenth the speed of light at such forces? I mean straight head on collision.

 

[Bikewer]

lots of sci-i writers have speculated about the problems of such impacts; coming up with ideas about "deflector shields" and similar devices.
I don't know the actual energies involved, but even at orbital speeds an impact with small pieces of space junk can cause serious damage.

I remember that years ago, NASA showed a deep pit in one of the shuttle's windows....Caused by a paint chip.

 

[marplots]

Seems doubtful. It isn't just the raw energy calculation but the amount of energy transferred in the collision.

I get (for a one gram pebble at 1/10 c), 4.5 x 10¹⁰ joules.
Wiki says 6.3 x 10¹³J for Little Boy.

But make your "pebble" a bit bigger (or faster) and you can get similar numbers. Just not seeing the same transfer of energy though. What keeps the pebble from going right on through?

 

[Rum]

I would have thought any aliens who have managed to attain interstellar travel would have overcome that particular problem. Not to mention dealing with pea shooter nukes.

My own view, which is based on nothing but a hunch, is that such aliens exist perhaps only incredibly rarely if at all. The more I read the rarer I suspect our sort of life is in the universe. And our sort that can escape their own solar system a lot rarer still.

 

[wea]

duplicate

 

[wea]

I'm not commenting the video since the link doesn't work for me, anyway 100 grams at a speed 0.1c should have a kinetic energy 1/100 megaton (4x10¹⁵J) if I'm not mistaken; being more concentrated on the hull than an atomic explosion, I think a higher "drilling" effect would be likely.

ETA: I see marplots preceded me, I'll just add that, even at "orbital" speed, the stiffness of the hull is often the major cause of the damage. A soft material just undergoes a hole, a rigid shield would be destroyed and the fragments so originated spread on the remaining structures with high energy.

 

[theprestige]

Seems doubtful. It isn't just the raw energy calculation but the amount of energy transferred in the collision.

I get (for a one gram pebble at 1/10 c), 4.5 x 10¹⁰ joules.
Wiki says 6.3 x 10¹³J for Little Boy.

But make your "pebble" a bit bigger (or faster) and you can get similar numbers. Just not seeing the same transfer of energy though. What keeps the pebble from going right on through?

1/10 c is misleading, I think. A ship traveling at 1/10 c will encounter particles traveling along its path, across its path, and against its path. At 1/10 c, overtaking a particle heading in the same direction might not be so bad, but encountering a particle coming the other way could get pretty exciting.

 

[Venom]

I'm sorry I'm having trouble imbedding. Weird.

This is the video by the way: https://www.youtube.com/watch?v=-lj2afg31oU

Again, he says it at 42:00 and I have no idea how fast they're assuming the craft to be travelling but at .1 x c it seems to be pretty damn powerful from reading your replies.
By the way would the above calculations be different if you had the meteoroid coming head-on toward the craft, which is the one traveling 1/10 c and and meteoroid coming in at a much slower speed?

Correct me if I'm reading it wrong but it seems as if you guys are calculating the kinetic energy of the meteoroid going at a tenth light speed.

 

[Gawdzilla Sama]

Micrometeorites would vaporize on impact. They'd do damage, but not as much as a fair sized rock.

 

[MG1962]

lots of sci-i writers have speculated about the problems of such impacts; coming up with ideas about "deflector shields" and similar devices.
I don't know the actual energies involved, but even at orbital speeds an impact with small pieces of space junk can cause serious damage.

I remember that years ago, NASA showed a deep pit in one of the shuttle's windows....Caused by a paint chip.

It was one of the reasons NASA was never too concerned about the Soviets building weaponized space platforms. As one NASA spokesman once said, all they would have to do is put 500 pounds of steel balls into orbit and the let the installation shred itself every orbit

 

[Reality Check]

At 42:00 of this video, the guy says that alien technology that crossed the cosmos would be able to withstand an attack by nuclear warheads because micro-meteoroids in space would do far more damage at the speed their spacecraft would be travelling in.

As other people have pointed out - a "pebble sized meteoroid" travelling at 0.1 c relative to a spacecraft will inflict a lot of damage.

If these aliens allow "pebble sized meteoroids" or nuclear warheads to impact then they are dead. Or for that matter gas and dust could be a problem. See Garrett, Henry (30 July 2012). "There and Back Again: A Layman’s Guide to Ultra-Reliability for Interstellar Missions" (PDF). for the effect on our proposed probes. There is a figure of 0.73 kg/m² of Al removed for a light density of dust for a 6 light year mission at 0.1 c.

However I can see that a technology to prevent meteoroids/gas/dust impacts would stop nuclear warheads, e.g. lasers to turn them into plasma at a long range and then magnetic fields to guide the plasma around the spacecraft.

 

[rwguinn]

I'm sorry I'm having trouble imbedding. Weird.

This is the video by the way: https://www.youtube.com/watch?v=-lj2afg31oU

Again, he says it at 42:00 and I have no idea how fast they're assuming the craft to be travelling but at .1 x c it seems to be pretty damn powerful from reading your replies.
By the way would the above calculations be different if you had the meteoroid coming head-on toward the craft, which is the one traveling 1/10 c and and meteoroid coming in at a much slower speed?

Correct me if I'm reading it wrong but it seems as if you guys are calculating the kinetic energy of the meteoroid going at a tenth light speed.

No difference. The impact is at .1C with a 1gm object...

 

[catsmate]

Seems doubtful. It isn't just the raw energy calculation but the amount of energy transferred in the collision.

I get (for a one gram pebble at 1/10 c), 4.5 x 10¹⁰ joules.
Wiki says 6.3 x 10¹³J for Little Boy.

But make your "pebble" a bit bigger (or faster) and you can get similar numbers. Just not seeing the same transfer of energy though. What keeps the pebble from going right on through?

But the energy of an explosion radiates spherically, little of it is incident on an object. Getting hit with even a small rock dumps all the KE.
The most efficient current fusion bombs yield about 25E12J per kilogramme of mass.

 

[smartcooky]

Whipple shields and other types of multi-shock shields might protect you from micrometeroid strikes.....

http://ares.jsc.nasa.gov/HVIT/index.cfm

.....but I can't see how they would protect you from a nuke!

 

[Samson]

It was one of the reasons NASA was never too concerned about the Soviets building weaponized space platforms. As one NASA spokesman once said, all they would have to do is put 500 pounds of steel balls into orbit and the let the installation shred itself every orbit

The movie gravity seemed to predict that. It has been suggested to me that space adventures will be impossible because the technology will be too late to avoid the man made space debris.

 

[bit_pattern]

I'm sorry I'm having trouble imbedding. Weird.

This is the video by the way: https://www.youtube.com/watch?v=-lj2afg31oU

Copy and past everything after the v= in your Youtube URL and wrap that in the yt tag:

Hence:

https://www.youtube.com/watch?v=-lj2afg31oU"]https://www.youtube.com/watch?v=-lj2afg31oU

Becomes

-lj2afg31oU

And, voilà

 

[Dr.Sid]

While pebbles are rare, there is also problem of constantly hitting lighter stuff, like solar wind particles (protons, alpha particles, or even single electrons). It would act similar to ram pressure during reentry. Sure, atmosphere outside solar system is pretty thin .. but there is some. And at relativistic speeds you cover huge volumes of space every second.
Also there might be pockets of higher density gas

 

[MG1962]

The movie gravity seemed to predict that. It has been suggested to me that space adventures will be impossible because the technology will be too late to avoid the man made space debris.

Agreed, the amount of junk in orbit is already a concern. And I think the issue will get worse as time goes by

 

[GlennB]

The movie gravity seemed to predict that. It has been suggested to me that space adventures will be impossible because the technology will be too late to avoid the man made space debris.

Agreed, the amount of junk in orbit is already a concern. And I think the issue will get worse as time goes by

All the advanced alien races made this same mistake, which is why they've never visited