the US Air Force's Plan to Stop the Earth Rotating
iflscience.com
iflscience.com
So no. To suggest "the US Air Force" had such a plan is most likely click-bait.
And you’re right, just because someone had an idea doesn’t make it a “plan”.
it would require 2.6 x 1021 kilograms (5.7 x 1021 pounds) of propellant, which is "about 500 times the mass of the Earth’s atmosphere".
According to the article.
>2.6 x 1021²¹ kilograms (5.7 x 1021²¹ pounds) of propellant
They don't say what propellant though, but I assume whatever kind of jet fuel they used at the time.
Consider angular momentum. It must be conserved. And a cool fact about that is that if you spin around and gain angular momentum, you steal it from the earth until you stop.
So all we need is a large number of very large and very fast spinning devices that we can turn on, spin up over say 5 minutes, and then stop afterwards. They'd probably need to spin at speeds that would shatter the atoms they're made of, of course, and the entire continent would need to be covered in them, I imagine.
But at least the atmosphere would be saved, and it wouldn't be a sudden stop and start.
Of course, the US military is not exactly known for its great sense of humor.
Why would they release such an idea? To overwhelm the opponent's intelligence agencies. They need to dedicate some time to analyze even silly ideas like this. If you send too much noise their way, you tie their hands down. To some extent.
If you look for patents filed by the US Navy, you'll find all sorts of even more ridiculous ideas (see [1], [2]). I'm pretty sure the US Air Force is ok to play the same type of games.
[1] https://www.vice.com/en/article/4adpv9/us-navy-has-patents-o...
[2] https://nationalinterest.org/blog/reboot/navy-just-filed-pat...
The only source of such huge amounts of energy would probably require converting more mass to energy than is easily obtainable in a few millennia of continuous mining and filtering for nukes etc.
I don’t see why you can’t build scaled up versions of those engines, strategically place them around the globe so that when they’re fired up the force they create would counter the Earths rotation.
I’m really curious if the idea is feasible no matter how ridiculous it is.
Let's say you are less ambitious that stopping the rotation of the entire Earth. You cut a small ring out of the Earth, a very tiny one: 100 km wide and 100 km deep. The circumference of the Earth is 40000 km, so the volume of this ring is 0.4 billion km3. The Earth's crust density is about 2.5 tons/m3, so we got ourselves a ring of one billion billion tons, or one billion Gigatons. This ring does exactly one rotation in 24 hours so that's 40000 km in 24x3600 seconds, that's 462 m/s, let's call that 500 m/s.
Let's unroll this ring. It has become a gigantic spear that travels through space with 0.5 km/s and weighs 1 billion gigatons. Our task is to stop it. We put a gun at the tip of the spear, and fire shells. The recoil of the gun will slow the spear down. The heavier and the faster the shells, the greater the recoil. The product of the mass of the shells and their speed needs to be equal to the product of 0.5 km/s and 1 billion gigatons. If the shells you fire have relativistic speed, you need to multiply with an additional factor to account for that, but we can't fire relativistic shells, so we'll ignore that.
Now you have a problem: obviously even the US Air force can't find one billion billion tons of stuff to fire into space. So we need to use less mass and higher speed. But the energy goes up as the square of the speed, as every kid knows (m v-squared over two). But hey, we have nukes, we can afford, right? Let's go crazy.
We can use ion thrusters. They shoot ions at truly mind-bending speeds. Up to 100 km/s. Two hundred times higher than the speed of our cosmic spear. So, we'll need to only fire 5 million gigatons of ions into space.
How much energy do we need? m v-squared over 2, everything in the metric system: m is 5e18 kg, v is 2e5 m/s, we get 1e29 joules. One ton of TNT has about 4e9 joules, so our energy requirement is about 25e18 tons of TNT, or 25 billion gigatons of TNT. The largest nuclear bomb ever in possession of the US Air force had a yield of 15 megatons. So, we are talking about roughly speaking 15 trillion such bombs.
But that is to stop only a tiny, tiny bit of Earth. A tiny ring that has a volume of 0.4 billion km3. The whole Earth has a volume of 1000 billion km3. You would need many quadrillions of Castle Bravo bombs to do the job.
Anyone have an antimatter containment device and an antimatter asteroid laying around?
If would take a lot of time but this could actually be done without requiring a huge amount of energy. Find bodies in elongated orbits that bring them from the outer solar system to near Earth's orbit. Send something out to them when they are still far enough away that it only takes a nudge to alter their orbit into one that will hit Earth and give them an appropriate nudge.
To get to the targets without having to use a lot of energy use unstable orbits around Lagrange points [1].
[1] https://en.wikipedia.org/wiki/Interplanetary_Transport_Netwo...
This Ellsberg guy from RAND and this Zimbleman guy from Smithsonian then both engaged in a bit of fun XKCD-style “what if” / “do the math” speculation, that also seems fine.
I don’t know what happened at the final step here that has this writer reporting on it like it’s a real proposal.