For this scenario, you are POTUS. NASA inform you that they have detected a massive asteroid on a collision course with Earth. Their calculations indicate that it will impact the Earth with a force of 10 Gigatonnes (plus or minus) and that Mexico City will be the approximate impact point. NASA then say that they can put together a rocket which will deliver a nuke which should induce a wobble which means that the impact point could be somewhere within a radius of 6000 km of Mexico City but they cannot control where. (This includes all the continental US apart from Alaska.) You have a matter of hours to decide, before it’s too late to complete the launch preparations. No one else knows of the approaching asteroid. The probability is that it will impact the sea; the vast probability is that it will not impact the US. But it might.
What do you do? Do you give NASA the go-ahead?
(And please, this is not a thread for Trump jokes or jibes.)
I don’t know enough engineering or science to know how to predict where it would fall.
But anywhere it’s going to be bad. If it hit Mexico City that’s pretty much as bad as withing the borders of the continental US.
So, as president, I’d give the go ahead. It can’t get much worse, but it could get less bad. As the OP states, even if not guaranteed, it’s more likely to splash down in the ocean.
Well, the first thing I would do is make Mexico pay for it…
Oh, sorry.
Actually, the first thing I would do is demand that NASA go back to the drawing board and calculate a better solution, perhaps with a larger nuke. An asteroid with 10 GT’s of energy would be less than a mile wide (rough n’ dirty calculation derived from the Chicxulub Asteroid which was six miles wide & delivered over 100,000 GT’s of energy, hope my math isn’t way off) so we should have the technology to destroy the rock completely or break it up into smaller bolides which would cause far less damage.
If there’s no time, and this really is the best an underfunded NASA can do… well, the most sensible course of action would be to let the asteroid take its course. Despite what you think, chances are a different impact site would be far worse, especially if it strikes the ocean. Any ocean impact would devastate thousands of miles of coastal cities and the likely total loss of life would be far greater than Mexico City.
On the other hand – since I’m POTUS, the politically expedient decision would be to go ahead and do something, anything, because even if it makes the situation worse, the political blowback would be much worse if I were perceived has having done nothing. Oh, and I’d be sure to blame my predecessor for not funding NASA properly which is what got us into this mess.
Right, my next question is how bad would it be if it hit the sea? I’ve got a feeling the word megatsunami might be used. Evacuating Mexico City would probably be easier than evacuating entire coastlines.
As the President, his primary obligation is to protect the lives of Americans. Any action that could result in jeopardizing American lives could risk getting him impeached, or worse. But then there’s the moral question of a “sin of commission” vs. a “sin of omission”.
Ah, well… That’s an argument against moving it; it could take out all of Texas, or southern California, or everything from Louisiana to Virginia, or the whole of the Caribbean, or all of Venezuela, or all of Peru…
The debris thrown into the atmosphere would likely take out all the agriculture in the Americas and maybe the world. Maybe a fast painless death would be better.
I’m inclined to let it go. I think my conscience would handle knowing I’d caused deaths by doing nothing rather than causing deaths by doing something.
I believe that climate studies have shown that a comet landing in the sea is worse than a land strike. More severe weather problems, spread over the whole earth. So do nothing.
If we see it coming, so does a substantial chunk of the rest of the world. Do we have the right to unilaterally make a world altering decision? Do we have the ability to keep some other country from making a similar choice we don’t like? Most of the announced nuclear powers probably have some sort of missile they could shoot at the incoming asteroid. If we act unilaterally and cause the asteroid to hit another country, have we committed an act of war?
I think I’ll start putting together all the forces I can muster for the relief effort for Mexico City, and also looking into contingencies if other countries act in ways that make it worse for us. I’m not going to take the shot on these facts. If the thing were going to hit a U.S. city, I might chose differently.
10 GT is pretty much nothing geologically. An extinction-level event would require an impact orders of magnitude greater. The K-T impact was 100 Teratonnes.
I know that citations still give 6 miles for the size of the Chicxulub asteroid, but that calculation was made when the crater was thought to be smaller than it actually is. IMHO, the estimate is due for an upgrade to closer to 10 miles. There is no way in hell we have the technology to destroy even a one mile rock. An asteroid is as likely to be a “rubble pile” as it is to be a single solid object anyway. And being broken into smaller parts doesn’t make it less dangerous–no matter if it is one piece or one thousand pieces, the same amount of energy is being dumped into the atmosphere and lithosphere.
Going with your figure of a 1 mile asteroid (not wanting to do the math myself) would result in a crater around 10 miles in diameter, and the heat and overpressure would kill pretty much everything within a couple of hundred miles or so of that. Eardrums might be ruptured for a few hundred miles outside that zone. It wouldn’t be a good day in Mexico, but it wouldn’t be anything close to a mass extinction event.
If you had no ability to make it miss the Earth entirely and no ability to steer it to an empty spot of desert, then leaving it alone is probably as good a bad option as any.
Okay, playing around with an impact calculator, a 10 GT blast would be an impactor somewhere in the range of 1,500 feet in diameter and create a crater less than 5 miles across. Someone a hundred miles from it would experience an overpressure of only around 1.8 PSI and a sound of only around 80 decibels. So a pinprick.
