
Air Force 'rods from god' kinetic weapon could hit with nuclear-weapon force - vezycash
https://www.businessinsider.com/air-force-rods-from-god-kinetic-weapon-hit-with-nuclear-weapon-force-2017-9
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millstone
> 20 feet long, 1 foot in diameter tungsten rods

I was curious about the price of this so I did some monster math (FYI complete
arms layman, serious errors are likely).

Raw materials: Volume is 15.7 cu ft = 444,574.5 cm3. Density is 19.3g/cm3 =
8,580 kg. Estimated price of $30.3k per metric ton [1] = $260k in tungsten.
Cheap.

Now for launch price. SpaceX advertises $90 million for 8 metric tons launched
into low-earth orbit [2]. Yowza.

A single Trident submarine based missile is in the order of $65-$100 million
depending on various sources. So cost-wise these seem within the same order of
magnitude as nukes.

1: [https://www.metalary.com/tungsten-
price/](https://www.metalary.com/tungsten-price/) 2:
[https://spacenews.com/wp-content/uploads/2016/05/spacex-
pric...](https://spacenews.com/wp-content/uploads/2016/05/spacex-price.gif)

~~~
ChrisGranger
That price per ton doesn't include making it in the desired shape, though,
right? Tungsten is very tough to work with, so I imagine that'd add
significantly to the price, though I've no idea how much.

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ars
It just needs to be more or less a rod. The exact shape doesn't matter much,
so there's not going to be much working it, just melt it into a rod and done.
(There are some ceramics that can handle the necessary temperature.)

You can also sinter it, it doesn't need to be especially strong, just hold
itself together while falling, and sintering can make it strong enough.

The strength plays no part at all when it impacts. At the energy involved it
might as well be a noodle. It just needs to handle the heat and resistance of
reentry. Mainly heat.

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taneq
> The strength plays no part at all when it impacts. At the energy involved it
> might as well be a noodle. It just needs to handle the heat and resistance
> of reentry.

So why tungsten, rather than a tungsten skin on a lead bar?

~~~
Someone
_when it impacts_. You want your missile to reach the ground in one part, and
you want it to have low air resistance, so that most potential energy goes
into the kinetic energy at impact, rather than say, heating or melting your
projectile or the air.

Also, the density of tungsten is about 75% larger than that of lead. Iridium
and osmium are about 15% heavier still, at about twice the density of lead
(osmium is heavier, but by only 0.12%)

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sebazzz
How accurate can it be - or does it only work when there is almost no wind?
Also, isn't there a maximum velocity based on air drag - if so, can something
similar not be dropped from a plane?

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tgtweak
I'd imagine at that speed (mach 8) it spends only a few short seconds in the
part of the atmosphere that is dense enough to cause it to deviate from wind.
Maybe a few metres? The thing I was more curious about is how they drop it
from non-geostationary orbit and still have it entering the atmosphere and
landing at the right place.

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Phlarp
It would need a precise retrograde burn at a precise orbital location. This
means it will be slower than surface based nukes and have a highly variable
time to target. At a low orbit this could be 90 minutes, at geostationary
orbit it could be almost a day, but it will always vary based on the location
of the target and the weapons orbital position when the order is issued.

~~~
tgtweak
I think they'd just get very strategic about the direction they launch it from
the satellite. They mentioned 15 minutes in the article but that would require
multiple satellites in the sky. The idea of putting rocketry and guidance
systems omboard seems plausible too.

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Phlarp
You can't deorbit something just by "dropping" it from a satellite. If you
want to target a single "rod" they would need independent onboard guidance and
propulsion.

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zaro
But why, there are already more than enough ways to kill people. And yet
somehow sane and affordable healthcare is out of reach.

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phendrenad2
To be fair, coming up with new weapons is a lot simpler than fixing the
world's healthcare systems.

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l0b0
In what sense? In the "we have the technology, medicine _and money_ for people
to live healthy well into their seventies but we choose to spend it on
doomsday machines instead" sense? In the "our armed forces are now so well-
equipped and well-funded they would simply take over if we tried to cut
funding to reasonable levels" sense? In the "everybody else is an enemy"
sense? What a lot of nonsense.

~~~
phendrenad2
I meant in the "give billions of dollars to weapon manufacturers and they'll
keep inventing crazy shit, but you can't even begin to enumerate the number of
organizations and agencies you'd have to give funding to in order to effect
change in our systemically flawed healthcare status quo" sense.

In other words, it's a complexity problem. It's easy to take money, throw it
at a defense contractor, and get weapons out the other end. But to change
healthcare, thousands of laws would have to be changed, and hundreds of
government agencies would have to change their daily operations. And
politicians would use the change to polarize their voter base.

What we need is to educate the younger generations on the benefits of
universal healthcare, show them how it's the inevitable way of the future, and
eventually they'll get into office and do the hard work of making the
necessary changes. It may take generations.

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darkpuma
I'm pretty skeptical that the energy dispersed from a tungsten rod impact
would be dispersed in a manner similar to a nuclear weapon. That is to say,
while they may both be just as energetic, the nuclear bomb might be dumping
most of it's energy into thermal radiation while the tungsten rod, I would
expect, is dumping a lot of it's energy into shattering bedrock as it burrows
half a kilometer deep into the earth's crust. Yes, ultimately that energy is
dispersed as heat, the rocks pierced by the rod would get hotter, but instead
of the thermal energy being emitted in one horrible microsecond in the
atmosphere above the target, it would be dispersed over a longer time period
and over a larger area straight into rock.

That's just my intuition. I don't think these would actually be as effective
as the raw energy values might suggest.

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pdonis
_> I'm pretty skeptical that the energy dispersed from a tungsten rod impact
would be dispersed in a manner similar to a nuclear weapon._

You're right, it wouldn't. See below.

 _> the tungsten rod, I would expect, is dumping a lot of it's energy into
shattering bedrock as it burrows half a kilometer deep into the earth's crust_

Yes, that's the point: the expected use for these weapons is to hit hardened
targets underground, so you want the energy to be concentrated, not dispersed
like in a nuclear blast.

~~~
darkpuma
What's to say it would have the desired terminal effects when it hits the
underground bunker, instead of simply piercing the bunker and continuing
deeper underground? If the underground bunker is built with bulkheads, would
one portion of the bunker getting pierced by a rod necessarily turn people in
another section into hamburger meat?

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whamlastxmas
Guessing by lethal shockwaves are from relatively small explosions (like
packets of C4), I'm going to go ahead and guess the energy dispersed from this
would easily shatter all the concrete of the bunker and instantly kill
anything living.

~~~
darkpuma
Maybe, but I'm not convinced. With enough velocity, a ping pong ball can blow
a clean neat circular hole straight through a ping pong paddle. Fast moving
objects can cause extremely localized damage. On the other hand if you shoot a
fast at a plastic jug full of water, an incompressible fluid, it will shred
the water jug specifically because that water is incompressible. Fill the jug
with air or sand and you'll then find that the jug remains intact when you
shoot it, save for two bullet-sized holes through both sides.

If the tungsten rod is able to borrow through hundreds of meters of bedrock,
it seems to me that's a sufficiently efficient penetrator that it might 'ice
pick' straight through the target bunker dumping only a small fraction of it's
energy into the bunker, as it then goes deeper through more bedrock.

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whamlastxmas
Your ping pong ball example is fairly counter to everything I've ever seen but
I'm no physicist. I would be very surprised if there's any velocity that would
put the ball through the paddle without completely destroying both

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dvh
I have my doubts. You would have to stop it from orbiting first (8km/s). What
kind of rocket would be needed to get 8km/s deceleration of 12 tons on LEO?
And it would only gain 10km/s. Why not go directly from the ground then?

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bagels
It doesn't even take 1km/s to deorbit.

[https://space.stackexchange.com/questions/12011/how-
could-a-...](https://space.stackexchange.com/questions/12011/how-
could-a-90-m-s-delta-v-be-enough-to-commit-the-space-shuttle-to-landing)

~~~
darkpuma
Yeah but you'd want your orbital kinetic weapon to pass through as little
atmosphere as possible to minimize aerodynamic breaking and to reduce the
accuracy problems inherent in those aerodynamic effects. The steeper the
reentry, the better, which means a greater delta-v requirement.

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Y_Y
There's an economic incentive for the moon base! Since it's so expensive to
bring heavy payloads up by rocket we can just mine them on the moon. It surely
won't be too long until the US needs to mass-produce the godrods anyway.

~~~
Someone
From the moon, you don’t need high quality weapons; you can compensate by
increasing mass. And that moon base could become independ3nt because of its
ability to launch rocks
([https://en.m.wikipedia.org/wiki/The_Moon_Is_a_Harsh_Mistress...](https://en.m.wikipedia.org/wiki/The_Moon_Is_a_Harsh_Mistress#Book_3:_TANSTAAFL!))

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bcOpus
Independence requires more than the ability to “drop rocks” it requires total
self-sufficiency. Without that you’re bombing the people who can kill you just
by withholding essentials like food, water, and air. No one is even pretending
that a colony on the moon or Mars could be self-sufficient to thst degree with
anything like our current technology.

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Someone
No village or small city is self-supporting nowadays. Why would a moon base of
similar size be different?

What matters is whether enough money flows in to buy elsewhere what you can’t
produce.

If (a big if, but an assumption in Heinlein’s novel) a moon base can be made
profitable, and kids get born there, so that people end up thinking of
themselves as citizens of them moon, would it be fair if most of those profits
keep ending up on earth?

In Heinlein’s novel, the idea is not that those living permanently on the moon
bomb those on earth (even though that does happen), but that they use the
threat of bombing them to get a fairer deal.

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cpeterso
Carl Sagan argued against developing the technological methods that would be
needed to defend against asteroids hitting the Earth because the methods
proposed would more likely be used as weapons against the Earth.

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drivingmenuts
Pretty soon we’ll just dropping small meteors. Farming them might not be
cheap, but we’re not going to run out of them.

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kumarvvr
Always have been curious about bringing outerspace stuff to earth.

Lets say we learn to mine asteroids, wouldnt the extra weight added to earth
affect its orbital mechanics in anyway?

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ygra
Considering that lots of stuff already ends up on Earth from outer space, I
doubt it has a meaningful effect. We also throw stuff from Earth into space
(the planet does so without us as well).

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ars
If this has "nuclear weapon force", then the rocket used to launch it also
contains that much energy.

A quick bit of match says the space shuttle energy is about 1 kiloton of TNT
equivalent. That's a pretty small bomb.

Maybe the new launch systems are more powerful.

Although it seems simpler to just fly a rocket full of fuel at the target.

~~~
darkpuma
With a series of rocket launches, bringing multiple boosters up to the rod,
you could raise it to a higher orbit incrementally than a single rocket would
permit. But this would be very expensive and I'm skeptical of the practical
value of this sort of weapon in the first place, even if we assume the rod is
given equivalent energy.

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rscho
"the moon is a harsh mistress"

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ggm
The cost thing, they need to do inflation-adjusted dollars. They wrote this
bit really badly. The cost of launch as dropped, kg for $, over time. But,
also inflation happens so a million $ isn't the big deal it was.

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frv103
Interesting that this was literally the major plot point in one of the GI Joe
movies. I wonder if they got the idea from the movie. If you google around,
the weapon in the movie created a lot of discussion about the real life
viability and physics involved about this exact topic.

Here’s a clip of the weapon being used in the movie:
[https://m.youtube.com/watch?v=jOKf5r_JMAo](https://m.youtube.com/watch?v=jOKf5r_JMAo)

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mtarnovan
"During the Vietnam War, the US used what it called "Lazy Dog" bombs. "

Sure, they got the idea from the GI Joe movies /s

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yardstick
Not the op, but just wanted to note various technologies in the past have been
inspired by fiction: [https://screenrant.com/star-trek-real-life-
gadgets/](https://screenrant.com/star-trek-real-life-gadgets/)

It’s a symbiotic relationship at times. Eg Computers became a thing, fiction
ran with it and made up hand held tablet computers, Tricorders, universal
translators etc, which materially (not always exclusively) influence future
technology designs and directions. Today we have real tablet computers,
universal translators etc which were inspired by fiction.

Edit: I missed the specific point being made that the Vietnam War was well,
well before the GI Joe movies in question. Apologies!

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mtarnovan
Sure. I just wanted to point out that the linked article describes similar
weaponry used by the US in Vietnam, so the point about inspiration from a
movie is kinda moot.

~~~
yardstick
Ah right, apologies I missed that! You make a fair comment given the GI Joe
movies came out decades after the Vietnam war.

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scotty79
Rod of god sounds funnier than rods from god. Let's call it that.

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Ritsuko_akagi
lance of Longinus?

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FlowNote
A $220 million per shot rod of God can burrow deep. How do you maximize the
value of that shot? Wiping out a city? Taking out military target? Pfft, nay.

How can you make a $200M shot free up trillions in liquidity?

You target the bunkers of billionaires and wipe out all of the blackmail they
store. That'll justify the high cost per shot eaaily.

