How could a specific asteroid be diverted to impact the earth?

Here's a quick guide to changing the orbit of an asteroid:

1. Figure out where it is. This is the crucial bit. You need to know its position, mass, velocity, orbit, size, density, and composition, and perhaps one or two other parameters. These are crucial, especially the first three. You'll need all this data to model its orbit and what will happen when you deal with it. Now, you might not have time to launch a probe to it (or divert another probe near it), so you'll have to make some educated guesses. If you can get good images of it, you should be able to figure out its size, position, and velocity.
2. Predict its future. You'll need a lot more than a crystal ball for this. Create a computer model (multiple ones for different scenarios, if possible) that predicts its orbit, both past and future. Create a model depicting the solar system, and put in the asteroid. Then you can figure out its closest approach to Earth in the near future. Take some measurements from this model, especially concerning its position and velocity at a certain time.
3. Start building. Unless you're a Jedi, you won't be able to move this thing with just the power of your mind. You'll have to send something up there to do something about the asteroid. Either retrofit an existing rocket or build one from the ground up (though again, you may not have time to start from scratch) and make sure it is capable of delivering objects beyond Earth orbit. Also, create a payload. This is going to be the thing that will interact with the asteroid.
4. Launch. At the proper time, launch the rocket and its payload. Make sure the payload isn't injected into Earth orbit; if this happens, it will be useless. The craft must escape from Earth's gravity if it wants to do anything. This is the only way to get it near the asteroid.
5. Interact with the asteroid. This is a bit of a broad title, but there are few different approaches you could take. I would ram the asteroid with the craft to transfer momentum and change the asteroid's orbit. This would have to be done with extreme precision, though. Ram it at just the wrong velocity and it could miss Earth by thousands of miles.

6. Continue taking data. I almost forgot - make sure you have a backup craft (and rocket). Lots of things could go wrong along the way, and if you're out to destroy civilization, you need a contingency plan. Even if you manage to hit the asteroid, you could have hit it too hard or too softly. Be prepared to launch again to correct the orbit.

   Anyway, keep collecting data from the asteroid. You'll get better information as it nears Earth, which could help you if you need a second launch. If you have a lander on the asteroid, that could be a great source. Alternatively, have part of the spacecraft continue to do a flyby with the asteroid while the other half impacts.

7. Wait. There isn't a lot you can do from here. Just sit back, relax, and get your affairs in order. If something has gone wrong, though, make sure you have redundancy and go back to step 4. Or step 3, if you have the time and completely forgot.

I don't know how much force it would take to move the asteroid in question. The NASA page says it has a mass of $2.4 \times 10^{13} \text { kg}$, which is quite sizable. The craft would have to be either very massive (a downside because you have to get it off Earth) or be going very fast to make a difference. The choice is yours. It also depends on just how much the asteroid's orbit must be changed in order for it to hit Earth.

As you asked,

The page estimates the magnitude of the impact at 8.6e+05 MT. Assume it hits the Pacific Ocean. Could humanity survive this impact?

I think we'd have some trouble. The largest nuclear bomb ever detonated, the Soviet Tsar Bomba, had an energy output of an astonishing $50 \text { megatons}$. This asteroid's impact (as NASA's estimates have it) would produce many times that amount - even if it didn't directly impact Earth.. Now, if we changed the orbit of the asteroid just enough so that there would be a direct hit, a lot more energy could be released. But it would have to be timed just right. Precision here is everything.

What would be the effects of this? Let me name just a few:

• Tidal waves. If you chuck a large rock into the middle of a pond, it makes quite the splash, right? Okay, now make that rock much bigger, and going at a much faster speed. I'd think you're going to have some issues. If it hits in the Pacific Ocean, many island nations could have severe flooding, and some minor atolls could sustain severe damage. The damage to continents would depend on just where the asteroid hit.
• Impact winter. We're going to have some chilly weather for a while. Clouds of gas and dust could be stirred up, although I've only heard about impact winters when asteroids (or other rocky objects) hit land. Hitting the ocean could reduce this issue. Still, I'd prepare for a long winter. You could get some serious sledding in.

I would think that's it. The water is going to absorb a lot of the energy of the asteroid. Also, it could break up upon re-entry, creating a lot of smaller rocks (yikes!). This would further dissipate the energy, although a much bigger are could be effected, and the resulting damage could be substantial.

posted over 9 years ago

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