Can we destroy an asteroid with a high powered laser?

[Bionic-Badger]

@Bionic-Badger still, that was 2 years ago and even if it can only generate so much energy for that long, we do not have that many nukes, in 10 minutes though, we could shoot this 60 times. Mabye to date, it could have had another amplifier added for a power of 1000 terrawatts :eg:.

60 x 30 femtoseconds x 300TW = 540 joules ~ 100W light bulb on for 5.4 seconds. Even if they kept firing that laser for those two years since that article, it'd produce only about 1/75th the energy of a single ton of TNT. The MIRACL megawatt continuous laser would need to be run for more than an hour to produce as much energy as 1 ton of TNT. That laser works by damaging the projectile, causing it to self-destruct, not vaporization from the energy of the beam itself. It's really amazing how much energy is in chemical and nuclear reactions.

Even nukes would probably be too weak to do much to an asteroid, if it weren't detected in time to use other methods to deflect it away over time like solar sails, or rockets, or asymmetric coloring.

 

[Blord]

If they are forseeing the asteroid is hitting the earth in 2029, there is enough time to plan a mission to the asteroid and with one calculated nukeblast to put it out of the trajectory.
The asteroid don't have to be destroyed completely, just a little push in the early stage is enough to miss the earth.

It will be a real bummer if it hits the moon and pushing the moon out of its orbit and on a ramping course with earth.

 

[Coherent Light]

2029 is not the problem it's 2036 when it returns!! If it goes through the keyhole in 2029 it WILL HIT in 2036.

 

[Blord]

No, the earth is in an orbit around the sun. It will be pure coincident if they meet again in 2036.

And in 2036 we have already developed the Death Star weapon. Ask Darth Vader how to make one.

 

[Coherent Light]

Well the Russians say that they are going to intercept apophis to make sure it will not hit the earth..........UMMM just guessing that if They do that the probability of a hit goes up to 100%, and it will most likely strike their old foe Washington DC. Glad I'm out west.

 

[millirad]

Or pass close enough to the moon to put it in a really eccentric orbit that causes really low tide and then massive tidal waves every day.

It will be a real bummer if it hits the moon and pushing the moon out of its orbit and on a ramping course with earth.

 

[Benm]

Back to the start:

I was watching The Universe on National Geographic. If Apophis will strike on 2029, can they construct a laser powerful enough to maybe "Vaporize" the asteroid?

I think the realistic answer would be 'no'.

Even if you had some extremely powerful laser and targetting system, all it would effecvtively do is heat up the asteroid. First of all you would have to heat it to melting point, and then to the point where it starts evaporating. The vacuum in space will help the latter process, but it would still take a tremendous amount of energy.

In order to vaporize the asteroid you would have to deposit enough energy onto it it vaporize the entire thing, but even if you could, the question remains what good it would actually do.

Melting and vaporizig an asteroid will not alter its trajectory at all, in only makes a differece between a solid object, molten blob or could of gas colliding with the earth. The molten blob vs solid rock isn't likely to make a difference at all, so lets just dismiss that as a solution.

Vaporizing the thing will make a difference, but the outcome would still be very unpleasant - a huge could of gas would strike the atmosphere, possibly resulting in radiation at ground levels, and likely disturbing sattelite communications, even destroying sattelites that would otherwise be missed completely by the solid asteroid.

I think the only viable solution would be to alter the course of the asteroid such that it just misses the planet. This could perhaps be done by nuclear blasts at one side. If there is more time to act, it could be feasible to park some rocket engines on its surface while it is still far away, alterting the trajectory ever so slightly to miss the earth.

The problem is that its more likely to get an asteroid strike with very little advance warning. We know of many asteroids, comets and such that will pass by the earth in years or decades. But the true concern should be the ones we do not see coming at all, or just days before they will impact. Defending at those is still beyond human capability at the moment, but we should be lucky it does not happen very often at all.

 

[magonegro]

Knowing the orbits of as much objects as possible, we potentially could attach small reactors to smaller objects to modify its orbits and use them like bullets against Apophis, taking advantage of its complementary movements and LOTS o kinetic energy, and thus producing a much more powerful impact per gallon of fuel used in the reactors. Cons: Takes time to plan this and maybe we couldn't find a suitable object to be converted in a bullet. Also, this need very accurate aiming. Another possibility is to modify the orbits of these little objects along the years to put them in a controllable and known zone, to be used like bullets when needed.

 

[Benm]

That would be difficult indeed, especially the finding and planning part.

I presume that something would be worked out if an object was discovered that is on a collision trajectory but will hit after at least a number of decades. With these known objects, the advantage is that they usually pass by the earth closely several times before becoming a real danger, and there is room for a slight course alteration to result in a big difference after a decade.

Altering course by a fraction of a degree would be completely effective if the object has one or more passes to go before impact. To alter the course of one that will not make a pass but comes straight at us would be much more difficult, since you would:

- have to get whatever moves it out to as large a distance as possible
- have to make a major course alteration to avoid collision

The kind that kills off most life on the planet doesnt happen often though: About once in 100 million years on average. Asteroids that leave impact craters large enough to level a major city are more common, about 1 per 1000 years.

Such a thing isn't the end of the world though, and if the impact point can be calculated, simply evacuating the area and rebuilding the whole city could be more cost effective than trying to muck with the asteroids trajectory. The latter could also be an ethical problem: What do you do when you can alter its course sufficiently to avoid hitting a city, but only such that it impacts elsewhere on earth? I think you may have a conflict on your hands if that happens, especially if this 'elsewhere' is on foreign soil.

 

[tlanzetta]

Im pretty sure lasers only go so far because of the gravity of earth bends it adventually

 

[AJ_Dual]

Im pretty sure lasers only go so far because of the gravity of earth bends it adventually

(facepalm)

While it's true gravity can bend the path of light, the entire mass of the sun can only bend starlight coming from it's edge by a degree or so.

The mass/gravity of the earth would have a negligible effect on any laser beam. Although such a system if it were even to be attempted would be all in space anyway.

 

[Benm]

That effect is both marginal, and bidirectional.

If you are looking at an object that is 'in the wrong position' due to gravitational bending or lensing of the light coming from it, you can just shoot back exactly in the direction the object appears. The gravitational effects will affect the beam such that it ends up exactly on target.

This is different from the typical example of trying to spear a fish that is underwater: In that case, the transistion between water and air does distort the optical path, but not the path of the arrow.

If you wanted to shoot a laser at a fish under water with a laser, you should aim to where it visually appears to you, not to where it actually is like you would trying to hit it with a spear.

 

[Arayan]

Im pretty sure lasers only go so far because of the gravity of earth bends it adventually

LOL, Earth is not a black hole

 

[ped]

"can we destroy an asteroid with a laser"


Yeah, get a WL arctic S3 , and throw it at the asteroid!

 

[Justin]

Vaporizing a small portion of the asteroid actually would alter its course due to reactive pressure from the outgassing. Comets do this when they are exposed to sunlight. However, it would take a lot of outgassing to significantly alter the path of a large planet-killing rock, so we would have to identify the target early and actually travel out there to give ourselves enough time to gradually push it away from a future intersection with Earth's orbit.

I vote for a very large array of small, controllable mirrors in a solar orbit, to focus solar energy over a very long period of time and slowly alter the asteroid's course enough to avoid a collision.

 

[Bluefan]

Vaporizing a small portion of the asteroid actually would alter its course due to reactive pressure from the outgassing. Comets do this when they are exposed to sunlight. However, it would take a lot of outgassing to significantly alter the path of a large planet-killing rock, so we would have to identify the target early and actually travel out there to give ourselves enough time to gradually push it away from a future intersection with Earth's orbit.

I vote for a very large array of small, controllable mirrors in a solar orbit, to focus solar energy over a very long period of time and slowly alter the asteroid's course enough to avoid a collision.

Throwing your mirrors at the asteroid will probably be more effective.