If we learned that an asteroid impact was eminent, what could we do about it?

Question

Say we knew that in 2016, an asteroid the size of Manhattan was going to enter our atmosphere. We have 10 years to do something about it. What could we do?

Answer 1

There are many possibilities and we would probably put several different plans in place just in case one of them was to fail. We could use a propulsion device to steer it off course over a longer period of time. We could also use a series of nuclear explosions to nudge the asteroid off course. last resort would be destroying it with a nuclear device. We would probably need to use more than 100 nukes because of the number of smaller asteroids created. We could have many layers of nuclear devices, with each layer farther away. Asteroid hits first layer and is broken into smaller pieces, most of which are still headed towards earth. Smaller pieces hit second layer and are made yet smaller. We could make as many layers as we wanted and could perhaps minimize the severity of the consequent impacts significantly.

Answer 2

I think that in 3 years, we could build a very large nuclear electric propulsion (NEP) system and launch the components into orbit for assembly by the shuttle crews or perhaps the ISS crews.

From there, we could go to the asteroid, anchor the NEP to it, and turn it on. It would alter the course of the asteroid just enough to miss earth. It would be an interesting project, I suspect that the NEP would have to be refueled several times. (Remember, your asteroid is the size of Manhattan.) We'd have to develop a lot of technology to do that.

The real nightmare would be to discover a large asteroid would collide with the Earth in 6 months. There's nothing we could do at all. We'd have to try to nuke it, and the probability of success would be very low.

Answer 3

A tip of the hat to Otis, but Karl deserves a mention too.

I'd agree that a nuclear propulsion unit would be the kind of unit with the power and duration required for an emergency scramble like this... ten years is a very short time to respond to an incoming rock - particularly one the "size of Manhattan."

Whether or not it would in fact be enough, would depend a great deal on how quickly we could get it there.

If someone's going to shoot this notion down, this is where they'd have to do it: by showing us via calculation that there's no way a feasible nuclear-thermal or -electric type engine could possibly be put on the menace in time. It may or may not, I don't know enough to run those numbers.

Karl points out that we'd be wise to have multiple programs going at the same time. I nominate building an Orion drive deep space tug on Earth and launching it at the planet-killer.

Nuclear pulsed-propulsion, uses fission bombs to lift a few thousand tons of payload from Earth and then embark on a interplanetary mission. (Actually, it's also possible to slap a passel of solid rocket boosters on it into LEO, thus avoiding most - not all - of the fallout. Desirable - if we've time to add this feature.)

We'd need to get hundreds of tons of payload into orbit anyway, and have up there *yesterday.* No orbital assembly, build that mother in a shipyard, tow it out from the continential shelf, B*A*N*G.

It could carry a nuclear rocket, or if that fails, butt up against the incoming rock and force it off trajectory.

Is that butch or what? :>

Answer 4

If the aftermath of 9/11 and Katrina are any indication, we would talk about it until it was too late. We would probably have some very good environmental impact studies completed in 5 years and then it would become a political issue and everyone would start pointing fingers in an attempt to blame someone for standing in the way of saving mankind. The current administration would ultimately be blamed for lack of leadership and replaced in the next election just in time for the thing to hit. The new administration would then nobly accept responsibility and fire the head of FEMA and hold Congressional hearings while the remaining rest of us struggled to survive and overcome the devastation.

Answer 5

Assuming we had a plan in place, interesting to look at a few numbers.

Say its roughly spherical, 5 miles in diameter and has a specific gravity of 3. The volume would be about 10^13 cf, and the weight about 1.8 x 10^15 lbs.

Assume we are going to nudge it to one side, rather than speed it up or slow it down. To cause it to drift off to the side about 4000 miles in 10 years, the new side velocity would be about 0.067 fps. The imparted energy = 1/2 m v ^2 /32.2 = 1.3x10^11 ft-lbf, or about 1.7 x 10^11 joules. This is only about 0.04 kT of TNT energy, which seems doable. A series of detonations close to one side would probably give it enough impulse, if I did the numbers ok.

Answer 6

Given a ten-year window of planning something, we could figure out all the physics to make this plan work. Launch a space shuttle with some sort of explosive device on it. Plant or fire the device at the asteriod, just enough to deflect it off-course, causing it to pass by the earth without hitting it. It needn't be a large explosion, just enough to change the trajectory of the asteriod. And the sooner we would do that, the smaller explosion we would need, because of the distance from the earth.

Answer 7

We could send up a bunch of oil drillers in the space shuttle, land on the asteroid, drill a hole and stick a nuclear bomb deep down inside and blow the asteroid up from the middle - it has been proven to work

Answer 8

As others said above, we would have to find a way to alter its orbit - the sooner we do it, the easier it will be.

We don't want to blow it up, because then instead of one asteroid hitting us we would have several asteroids hitting us, spread out over a large area to boot!

Answer 9

We probably would argue for 9 1/2 years to verify that it really was going to hit.

We COULD...

hit it with rockets (landing would be too difficult) to modify it's orbit

orbit it with a massive metalic satellite and (through gravity) modify the orbit.

Take our chances

Answer 10

We could leave. Seriously, we could scare up the funding to put some of those old self-sustaining spacecraft-city ideas into reality, particularly on a 7-billion person scale.