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How can I protect a country against an unguided orbital strike/"rods from god" style weapon?

I was thinking maybe stopping the launch would be easier than stopping/blowing up the actual rods in mid-air, so how would you do that?

You can use technology that is likely to be developed within roughly 50 years or less from now.

The countermeasure must be able to be used more than once.

Money is not an issue.

Please ask for more information if further clarifications are needed.

Edit you can attack the launch vehicle before the strike and you can pick any sized country to protect but the bigger the country the better protecting Russia wins over protecting the Vatican. M.a.d is a last resort solution

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  • $\begingroup$ What are we protecting? $\endgroup$
    – Seraphim
    Commented May 4, 2020 at 22:45
  • $\begingroup$ A country like I said in the question, do you mean what kind of country? $\endgroup$ Commented May 4, 2020 at 22:46
  • $\begingroup$ What is launching the strikes? Can we attack the launch vehicles before the attack? $\endgroup$
    – Alexander
    Commented May 4, 2020 at 22:52
  • $\begingroup$ @Zeronineseven an idea of the size of the country would help. Protecting the Vatican (0.19 square miles of theocracy) is easier than protecting the motherland (8.65 million square miles of love and comradeship). $\endgroup$ Commented May 4, 2020 at 22:53
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    $\begingroup$ Use Soft Power: Encourage lots of tourism. Have frequent International Beer Festivals. Host Eurovision. Use straight-up propaganda to make your nation's Bikini Team popular and keep them popular. Nobody gonna bomb the Gorgania Bikini Team during FebruaryFest. $\endgroup$
    – user535733
    Commented May 5, 2020 at 1:32

4 Answers 4

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Unguided orbital strike has a predictable ballistic path. Intercept the strike rod.

  1. A thing in orbit has one way it can go. Its path can be calculated and predicted.

  2. A thing in orbit has one chance to drop a rod so the rod falls on point x. The orbiting thing cannot stop. If you can see the orbiting satellite and you know the target you know exactly when it is going to drop the rod.

  3. Hit the rod with something as high in the air as you can. A kinetic orbital weapon must be aerodynamic to maximize terminal velocity and energy delivered on impact and minimize energy shed to the atmosphere on re-entry. If you can hit it and make it tumble it will shed much of its energy to the atmosphere and slow down.

  4. Since I am setting this up, I will use something like an AEGIS system using 10 small railguns which shower the flight path with 1 kg Mach 8 projectiles. I would like a projectile which will disintegrate on its own before hitting the earth, and I find incorporating explosives inelegant, so they are made of dry ice in a gold foil wrapping.

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    $\begingroup$ Only problem here is that orbital period varies with height. The station holding the rods will likely be in low earth orbit, meaning they'll have an orbital period of about 1.5 hours. Meaning you will never have more than 1.5 hours warning, and usually less. And you don't know where exactly under that orbit it's aiming. It is likely the rods will not be totally unguided, they will have some cross-range capability. Making the ballistic path and target much less predictable. $\endgroup$
    – Ryan_L
    Commented May 5, 2020 at 0:19
  • $\begingroup$ @Ryan_L - why would a low earth orbit be preferred for a weapon like this? $\endgroup$
    – Willk
    Commented May 5, 2020 at 2:11
  • $\begingroup$ A few reasons. First, it means you will be over the target as fast as possible. Higher orbits have the same problem I mentioned above but worse. The target will have more warning the higher the satellite is. Further, these rods are very heavy, most of their cost will be in simply launching them. The higher the orbit, the higher the cost. They may also be easier to intercept. At a higher orbit, they will re-enter at a higher speed and with higher stresses. Any damage an intercepter causes is thus more like to disintegrate the rod. $\endgroup$
    – Ryan_L
    Commented May 5, 2020 at 2:17
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Mutually Assured Destruction

The most effective defense against attack is to convince your would-be attackers that they're better off leaving you alone in the first place. See my answer to a very similar question here. There isn't that much difference between how a JRPG Final Boss (tm) uses MAD (like in that question), compared to how it's played out in the real world.

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This may sound like a radical idea, but the best course of action may be to do nothing.

A "rod from god" is one of the least efficient ways of causing major damage you can imagine.

The highest velocity impact you will probably get will be from an Osmium bolt due to its really high density and melting point. Let's use a 5m long rod with a 100cm^2 cross-section as an example. At that size you have an 1129.5 kg projectile with a terminal velocity of about 2,480 m/s to impact with. This results in a maximum of 3,473.4 mJ impact. Now that may sound impressive, but for comparison, that is about the same amount of energy you get out of 75kg of rocket fuel.

To put that heavy of a rod into orbit you will need to burn about 20,000 kg of rocket fuel. The cost of fuel + osmium means that each rod would costs about 36 million dollars to put into space for a weapon system that has about the same destructive capability of a standard $20,000 surface-to-ground missile.

Combine this with the fact that they are not very easy to aim at ad-hoc targets because of the way orbital mechanics work, and not only do rods-from-god fail the weapon of mass destruction test, they utterly fail as weapons of regular destruction too. So, the countries of the world are all completely safe from being toppled by rod-from-god weapons with or without counter measures.

Given your criteria, larger nations like Russia are way less vulnerable because you simply can't destroy enough stuff to put a real dent in thier infrastructure. Leveling the Vatican could be done for a few trillion dollars, but if you're going to put that much money into leveling a small city, it's way cheaper just to buy a fully equipped aircraft carrier and support fleet.

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I would have killer satellites and/or a fleet of B-52s armed with either multiple kinetic kill vehicles (MKKV) launched via Pegasus rockets, or MIRACL units. From the lower stratosphere, atmospheric turbolence is negligible and could allow a "soft kill" on incoming rods (destroying their aerodynamic surfaces and/or guiding systems).

If necessary, in fifty years I am quite confident we could come up with a more agile version of Project Excalibur capable of hard kills against freshly-launched rods.

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