Defending the Earth from meteors using lasers

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Discussion Overview

The discussion centers on the feasibility of using laser beams, particularly chemical lasers, to defend Earth from meteors. Participants explore the theoretical and practical implications of this approach, including energy requirements, technological limitations, and alternative methods of planetary defense.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose using gas lasers to create plasma that could burn meteors before they enter the atmosphere.
  • Others argue that the power requirements for such lasers would be equivalent to hundreds of nuclear power stations, raising concerns about energy sourcing and storage.
  • A few participants suggest that the cost of implementing such a laser system should be considered, with some emphasizing the importance of saving the Earth over financial concerns.
  • There is a discussion about the practicality of using nuclear explosives as an alternative method for deflecting larger asteroids, with some expressing skepticism about the effectiveness of lasers for this purpose.
  • Some participants question the assumption that burning meteors would eliminate them, suggesting that it could result in more dangerous debris.
  • Concerns are raised about the implications of deploying powerful lasers in orbit, including potential military applications and environmental impacts.
  • Participants discuss the limitations of current technology and the potential for future advancements in both laser and nuclear technologies.

Areas of Agreement / Disagreement

Participants express a range of views, with no consensus on the effectiveness or feasibility of using lasers for meteor defense. Some support the idea while others raise significant concerns about energy requirements, costs, and alternative methods.

Contextual Notes

Participants highlight various assumptions, including the energy needed to vaporize meteors and the potential consequences of using lasers versus nuclear options. The discussion reflects uncertainty about the capabilities of current technology and the implications of proposed methods.

Dovla
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Hello all. I am new here.

I have an idea about defending the Earth from meteors using laser beams. I thought about using chemical lasers to burn the meteors.

The first phase is that we use gas lasers if possible to create plasma by heating the gas and to use that plasma beam to strike at the meteor before it enters the lower atmosphere. The end result of this would be that the meteor would be burned. Now the second phase.

For this idea, we would need many chemical lasers in many areas. But some would be located on satellites. Those on the satellites would target the far-Earth side of the meteor so that both sides would simultaneously burn.

On this forum there are many professional physicists so I am interested to see what they think about this, looking at it from physics perspective.
 
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Conceptually the idea is not impossible.
The trouble is that lasers powerful enough to accomplish this would require a power source equivalent to hundreds of nuclear power stations.
 
Your idea would be a lot more interesting if it came with a cost proposal.
 
rootone said:
Conceptually the idea is not impossible.
The trouble is that lasers powerful enough to accomplish this would require a power source equivalent to hundreds of nuclear power stations.
If we advance enough, we might be able to store energy. I know we will not be able to keep it forever, but we might be able to make the energy circulate and we might be able to harvest solar energy using panels and store them or use nuclear energy.
 
.Scott said:
Your idea would be a lot more interesting if it came with a cost proposal.
I think it is more important to save the Earth than to save money.
 
Dovla said:
I think it is more important to save the Earth than to save money.
That would be especially important if your method was the only one available.
 
Is it possible to turn gas in the laser into plasma by heating?
 
  • #11
Dovla said:
On this forum there are many professional physicists so I am interested to see what they think about this

It doesn't seem that way to me. It seems to me that having them point out problems is making you unhappy.
 
  • #12
Dovla said:
I think it is more important to save the Earth than to save money.
That's not really how we do things here on earth.
 
  • #13
Vanadium 50 said:
It doesn't seem that way to me. It seems to me that having them point out problems is making you unhappy.
You are thinking wrong. I want to discuss this with everyone,
 
  • #14
Dovla said:
So the problem is all about obtaining and storing energy?
Producing that amount of energy and releasing it more or less instantly is definitely a big problem in itself.
It also has secondary consequences in that unless the conductors used to carry the current are supercooled they will probably vaporize themselves.
Supercoooling thousands of tons of electrical conductors requires even more energy if it can be done at all.
Then you have the problem of the atmosphere; a fair amount of your hyperlaser energy will used up in ionising the air before it gets to the target.
 
  • #15
Dovla said:
I think it is more important to save the Earth than to save money.

Try comparing the cost of your proposal to the cost of simply nudging the asteroid out of the way so that it misses the Earth. If you start soon enough, only a very small push is sufficient to make it miss the Earth.
 
  • #16
phyzguy said:
Try comparing the cost of your proposal to the cost of simply nudging the asteroid out of the way so that it misses the Earth. If you start soon enough, only a very small push is sufficient to make it miss the Earth.
What if the asteroid is big enough that nuclear bombs cannot save us?
 
  • #17
Dovla said:
What if the asteroid is big enough that nuclear bombs cannot save us?
If it's that big, we should have sufficient time in spotting it and giving it a nudge. Nuclear explosives could cause issues with debris
 
  • #18
Dovla said:
Hello all. I am new here.

I have an idea about defending the Earth from meteors using laser beams. I thought about using chemical lasers to burn the meteors.

The first phase is that we use gas lasers if possible to create plasma by heating the gas and to use that plasma beam to strike at the meteor before it enters the lower atmosphere. The end result of this would be that the meteor would be burned. Now the second phase.

For this idea, we would need many chemical lasers in many areas. But some would be located on satellites. Those on the satellites would target the far-Earth side of the meteor so that both sides would simultaneously burn.

"Small" asteroids (say, below 50m) are not dangerous enough to bother - they can do only localized damage, not regional or global scale.

Asteroids larger than that are too massive to nudge away with laser evaporation (with today's technology).

Technology is going to progress, but ALL technology is going to progress, not only laser tech. With the possibility of heavier payloads being sent to incoming asteroids, and better guidance, it's more practical to send multiple multi-megaton nukes than building multi-terawatt lasers. (Also, for one, I object to anyone *having* multi-terawatt laser in Earth orbit!)
 
  • #19
Dovla said:
I have an idea about defending the Earth from meteors using laser beams. I thought about using chemical lasers to burn the meteors.

The first phase is that we use gas lasers if possible to create plasma by heating the gas and to use that plasma beam to strike at the meteor before it enters the lower atmosphere. The end result of this would be that the meteor would be burned. Now the second phase.

For this idea, we would need many chemical lasers in many areas. But some would be located on satellites. Those on the satellites would target the far-Earth side of the meteor so that both sides would simultaneously burn.
You seem to think that "burning" meteors (whatever that means) would make them simply vanish. What you will probably get is something coming at Earth with even more energy than it started with.
 
  • #20
nikkkom said:
(Also, for one, I object to anyone *having* multi-terawatt laser in Earth orbit!)
Yeah that sure could be a problem if it was deployed for regular warfare purposes.
Vaporizing an incoming large meteor is on the same scale as vaporizing a city.
Then again it might make fantastic projects like lightsail probes to other nearby stars realisible.
 
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  • #21
nikkkom said:
Technology is going to progress, but ALL technology is going to progress, not only laser tech. With the possibility of heavier payloads being sent to incoming asteroids, and better guidance, it's more practical to send multiple multi-megaton nukes than building multi-terawatt lasers. (Also, for one, I object to anyone *having* multi-terawatt laser in Earth orbit!)
Nuclear bombs can pollute our athmosphere, and nuclear bombs can't be used outside of Earth's athmosphere.
 
  • #22
Dovla said:
nuclear bombs can't be used outside of Earth's athmosphere.
Why is that?
 
  • #23
DrClaude said:
Why is that?
Rocket that travels into space will deplete its oxygen reserves so we won't be able to send it that far away. Lasers have bigger range and can be sent to bigger distances, we just need energy. With lasers, we can strike meteors when it is farther away thus preventing any unneccesary debris.
 
  • #24
Is it impossible to add an oxygen tank JUST for the reaction? I'm no rocket scientist, but I can't see that being an obstacle that will prevent creating a nuclear explosion.
 
  • #25
You have many misconceptions in this post:

Dovla said:
Rocket that travels into space will deplete its oxygen reserves so we won't be able to send it that far away.
We have sent rockets beyond Pluto. How far away do you want to send them? Also, why do you think rockets need oxygen reserves? Automated probes typically don't use fuel containing oxygen in deep space.

Lasers have bigger range and can be sent to bigger distances, we just need energy. With lasers, we can strike meteors when it is farther away thus preventing any unneccesary debris.

Lasers are subject to the inverse square law, so the further away you aim it, the less intense it is. This does not apply to a bomb, assuming you hit the target.
Also, why are you so fixated on blowing the thing up? The right answer is to modify the orbit slightly so that the asteroid will miss the Earth. This takes much less energy and is much more feasible.
 
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  • #26
You don't have to destroy the asteroid to defend the Earth. You just have to deflect it. So, a laser could perhaps vaporize some material on one side of the asteroid, causing a reaction force that nudges the asteroid slightly in the other direction.

Lensing by the atmosphere will create some aiming difficulties for Earth based lasers.
 
  • #27
Khashishi said:
You don't have to destroy the asteroid to defend the Earth. You just have to deflect it. So, a laser could perhaps vaporize some material on one side of the asteroid, causing a reaction force that nudges the asteroid slightly in the other direction.

BTW, the nuke can be used in a similar way. It can be detonated not on/under asteroid surface, but above it. This would evaporate top regolith layer. With careful selection of detonation point, you can tailor the "push" to your needs.
 
  • #29
Ok. I just wanted to hear your thoughts on this idea.
 
  • #30
phyzguy said:
Also, why are you so fixated on blowing the thing up? The right answer is to modify the orbit slightly so that the asteroid will miss the Earth. This takes much less energy and is much more feasible.

DrClaude said:
What you will probably get is something coming at Earth with even more energy than it started with.

Blowing it up at close range will probably make the situation worse. Blowing it up at a great distance may help as the trajectories of the resultant bodies will change as long as you get a sufficiently large explosion. If too small it will just coalesce again under gravity. Changing its course seems the better option. Attach some sort of engine on a poll and fire it up. The good news is that the technology and capability already exist for that option.

BoB
 

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