“Rods from God” is the nick-name given to a hypothetical orbital weapon for bombarding targets on the Earth from space. Just how feasible is this concept?
Cover graphics from Transformative Flight Plan (2003), a document which looks as though it was written by HYDRA but was actually prepared for and by the USAF. It talks of hypervelocity rod bundles as a potential weapon. (Image credit: USAF)
There are undeniable links between the spaceflight and military communities but apart from a few tests of anti-satellite weapons, the odd armed space station and laser battlestation there have been mercifully few weapons in space. Yet the idea of bombarding the Earth from orbit keeps coming up again and again. Thankfully it is ridiculous. I believe the idea is that having weapons hovering menacingly overhead will persuade your enemies to behave themselves. However this idea is stupid- I cannot think of a better word. Anyone who suggests such an idea must have learned their science from Tom Clancy books or Steven Seagal movies.
The current version of this mad scheme is the kinetic energy weapon and is usually described as scores, possibly hundreds, of tungsten (chosen for its high melting temperature and hardness) projectiles orbiting the Earth in formation or attached to a satellite ‘bus’. These could be either relatively small darts (weighing about 100kg) or large ‘phone poles’ (about 8000 kg each). When required these projectiles can be commanded to dive, singly or en masse, at targets on the Earth’s surface, smashing into the victim at orbital speed. As the projectile’s kinetic energy is released, the blast would be equivalent to a large conventional bomb (a 100kg projectile traveling at 7km/s would release about 2.5 gigajoules of kinetic energy, a tonne of TNT releases about 4.2 gigajoules). This would be a non-nuclear precision weapon, essentially a smart bomb that can target anywhere in the world. It is further claimed that the darts would be capable of penetrating deeply into the Earth’s surface enabling non-nuclear attacks on installations deep underground.
This idea is said to have originated in 1964 (but was revised and updated in 1975) in the mind of Jerry Pournelle, engineer, writer and consultant to the US Air Force. He originally named the concept “Thor” after the hammer-wielding Norse god of thunder. Pournelle said each projectile was
…an orbiting element some 20 to 40 feet long. It requires a GPS receiver to locate itself; a means of taking it out of orbit; an atmospheric guidance system, such as a means of changing its center of gravity (moving weights, small fins, etc.), and a communication system to give it a target and activate the system…Achievable accuracy has been estimated at ten to twenty feet CEP (Circular Error of Probability)
Pournelle assumed extremely cheap fully reusable single stage to orbit launch vehicles were just around the corner and would enable his concept to be quickly deployed, sadly no such craft have yet been built. Moving further into fantasy, Pournelle later had a smaller but more accurate optically guided variant of the weapon described as “crowbars” used by invading alien space elephants (really) to devastate the US military in Footfall (1985), a novel he co-wrote with Larry Niven. In this book, Niven and Pournelle introduced the concept
You take a big iron bar. Give it a rudimentary sensor, and a steerable vane for guidance. Put bundles of them in orbit. To use it, call it down from orbit, aimed at the area you’re working on. It has a simple brain, just smart enough to recognize what a tank looks like from overhead. When it sees a tank silhouette, it steers toward it. Drop ten or twenty thousand of those over an armored division, and what happens?
Subsequently similar weapons have appeared in other fictional works where they always work perfectly! A recent example is the movie GI Joe: Retaliation (2013) which is dissected in this video:
This artificial meteorite concept is often nicknamed ‘the rods from God’ even by its supporters, who usually claim it would be relatively cheap to set up (indeed some claim it already exists). They give the impression that at the press of a button, these rods will just fall from the sky on their victims. However it is not that easy. As each rod circles the Earth it is moving at least 7 km/s, to make the rod fall from orbit under gravity, we need to adjust its orbit to intersect the Earth’s surface. To do this each rod therefore needs to be attached to a rocket motor and its fuel tanks (or solid propellant), suddenly each cheap 100kg rod has ballooned into a multi-tonne vehicle, perhaps the size of a Soyuz spacecraft. At least it does not need a heatshield, a tungsten projectile could reasonably be expected to survive the expected heat of re-entry.
The ground-penetrating effects of such projectiles is grossly over-stated too- do falling meteorites of this sort of size always bury themselves hundreds of metres under the ground? Laboratory experiments show that objects striking the surface at speeds greater than 1 km/s are melted by their own kinetic energy before they penetrate the ground, effectively liquefying on impact. Rather than slamming into the target at 20 times the speed of sound, the rods may need to be slowed down to fast aircraft speeds to prevent them disintegrating on impact.
The problems of guiding each rod is usually dismissed with handwaving references to GPS, although some armchair space marshals also follow Pournelle’s fictional lead to suggest each rod would have its own imaging sensor to find and steer onto moving targets like tanks or warships. I have no doubt that the electronics are feasible but the rod now needs control surfaces hooked to its guidance system and sounds more like a missile than a cheap metal rod. Do these now complex projectiles require maintenance in orbit?
Finally, it is said that the rods can hit any target on Earth minutes after the KILL button is pressed. Once again, this doesn’t seem properly thought out. The rods can only hit targets on or near their orbital track, for weeks at a time some parts of the world would be invulnerable as their potential attackers would never come within hundreds of kilometers from their positions. The only way around this limitation is to have hundred of rods waiting ready in multiple orbits, requiring a ludicrous number of launches. Even if the target is directly under the rod’s orbital track, the attack may not be instantaneous, as those who order the attack wait perhaps 90 minutes for the rods to move around the Earth into position. Even the Joint Chiefs of Staff cannot overrule Sir Isaac Newton.
A rods from god bombardment would probably look a lot like this test of the re-entry vehicles of a LGM-118A Peacekeeper ICBM. The projectiles are highly visible; it would be obvious that an attack was taking place, so this would not be a weapon for covert strikes. Each reentry vehicle here is a large and complex piece of hardware, not a simple “crowbar” or “telephone pole”. (Image credit: USAF via fas.org)
The number of launches needed to deploy even a few dozen individually weighty weapons is glossed over by Rods enthusiasts. Assuming they are deployed, every rod (or their carrier satellite) will move around the Earth on a regular and predictable orbit where they will be observable from the surface by radar and optical sensors, so potential enemies will always know where they are. “Dropping” the projectiles from orbit is no actual advantage by the way, by the time they reach the surface they will have no more kinetic energy than was imparted to them by their original launch vehicle. After considering all this, to be honest, it would make more sense to launch each rod from the Earth’s surface directly to the target. To make them less vulnerable to preemptive attacks, perhaps the rods should be based in hardened underground silos or hidden in submerged submarines. Congratulations, we have just reinvented the ICBM!
The most recent unclassified mention of the concept is in a USAF document called The US Air Force Transformative Flight Plan (2003) which talks of “hypervelocity rod bundles” as a potential weapon in the post 2015 period. Note this mention in an official document does not mean the US military can magic this weapon into existence. There is a history among militaries world-wide of wasting billions on R&D into projects which are hopelessly impractical or even completely ungrounded in reality (see hafnium excimer bomb, atomic-powered aircraft, camouflage uniforms which make the wearer more conspicuous and using ESP for espionage). As of 2015 no kinetic-energy orbital bombardment system has officially been proposed or tested, never mind deployed.
The older version of the concept is the idea of putting nuclear bombs in geostationary orbit over a potential enemy country is still brought up from time to time. This is even more ill-conceived than the Rods from God. When you think about it, it is obvious that a geostationary orbit must be above the Earth’s equator. Now there are only thirteen nations on the equator and it hard to see why any would want to suspend a bomb over say, the Maldives or Gabon.
Even though they are sometimes put forward by apparently sensible people or organizations, “Rods from God” and other schemes for bombing the Earth from space are half-baked science fiction concepts. The cost of developing an orbital bombardment system would make the F-35 project look cheap in comparison. They are militarily pointless and hopelessly implausible. Similar damage could be inflicted more cheaply and easily by conventional ground-based weapons.
A cynic would say that clever diplomacy would avoid the need for the weapons altogether.
(Update: since I wrote this I have discovered the 2003 paper Space Weapons: Not Yet by Richard L. Garwin which discusses this concept and others. Garwin’s conclusions about how believable this concept is are very much in agreement with my own.)
(Article by Colin Johnston, Science Education Director)
Your claim that the rod’s orbital velocity would need to be cancelled is about as far from the truth as it gets. From a circular orbit with an altitude of 400 km, the delta v necessary to drop into an earth-intersecting elliptic orbit is about 120 m/s. Incidentally, this also leaves the projectile with way more energy than it would have if it stopped dead as you described. Much of this additional energy may be lost to atmospheric drag as it now follows a ballistic trajectory, but considering the additional mass allowed by the reduced fuel load, it should be more than made up for. The disadvantage here is a longer strike delay, but with terminal guidance it shouldn’t be too much of an issue.
As for issues with burning up in the atmosphere, the fact that it’s a tungsten pole renders the comparison to a meteorite rather misleading. Tungsten has a far, far higher vaporization energy and much better than structural strength than a meteorite, especially when considering that meteorites generally aren’t monolithic. Further, the rod shape means that it will have a tremendous sectional density and there’s no reason that reentry tiles couldn’t be used to protect the projectile further.
As to whether ground-penetrating impact is a real possibility, I don’t know.
Hi, thanks for your comment. I think you have a point in that I have oversimplified how the projectile is meant to fall and I’ll amend the post to reflect this.
You’re right too, that a tungsten projectile isn’t going to burn up on re-entry, I’ll fix that too.
Making a hole is easy. You just hit it more then once. Using the logic here, it was impossible to dig the Panama Canel because the shovel wasn’t big enough. As far as breaking orbit, a cpmpressed gas charge will do it. You obly need motors and fuel if speed is needed. A Rail gun would do the job. Please note that such a rail gun didn’t exist in 2004 when this article was written. PLus the number in ORbit will be in the millions, not dozens.
What makes this weapon desirable is that is is unstoppable. That and the small impact area. Dropping one on Assad would have saved 100,000 lives so far, mabe a milliion or more before that little dust up is done. No need to invade Iraq when you can plonk Saddam from orbit while he is floating around his pool.
What gripes me is that those who advocate peace and love will not accept responsibility for those killed by their silliness.
Hi John, thank you for your comments but I’m not quite sure that you fully appreciate the issues.
I don’t think this is correct, surely if it was correct infantry could then defeat tanks by blazing away at them with machine guns?
Again, are you certain about this? An orbiting satellite needs to lose a significant amount of velocity to re-enter on command, the only way we have to do this is by firing a retro-rocket. The smallest re-entry vehicles I know of are the “buckets” which returned film from KH reconnaissance satellites, have a look at photographs and diagrams of these, there is always a substantial rocket motor and propellant tank.
Let’s imagine each rod weighs 100kg in orbit (ignoring a deorbit system). This is the smallest mass I have heard quoted by fans of this idea. To set up the system you are suggesting needs 100kg x 1000 000 (=100 thousand tonnes) of stuff placed in orbit. To give this a context ESA estimates there are only 6300 tonnes of human-made material in orbit. You ought to try to compare this mass with the total mass launched into orbit by all the world’s space agencies since 1957. Setting up your system would require an incredible launch capacity (which I wish we had, it would help open up the Solar System for human habitation).
We’re straying a bit away from discussing space technology, but have you thought about what you are saying here? Advocating peace is “silliness”? Really?
see i hate people like you, you are the reason for the set back of technology. If the rods were build (which im sure they have been already) numerous space based technologies would be developed for civilian benefit. Look at Apollo, think of all the technological benefits that came because of that. And you are underestimating human innovation, as well as the militarys budget. Creating something that resembles project thor isnt outside the realm of possibilities. These if the space shuttle carries 115 tons into orbit and here you suggest a little 100kg payload is unfeasible is an insult to NASA and all space faring nations. Put a 1000kg payload we might have a space based weapon that has the energy of a M.O.A.B. potentially destroying small mountains, now wouldn’t that be cool?
Source please for your assertion that the Space Shuttle could place a 115 ton payload into orbit?
With such technology as the chance to refine the orbital ballistic system would a pinpoint L.A.S.E.R. orbital system be something else to consider? This technology could present a much more viable and beneficial system to many fields some military related yes, but also it can be transfered to the medical, economic, and energy fields. With such a system in place the advantages for offense as well as defense are very interesting and exciting.
space shuttle: 24,000 kg
Saturn V, 118,000 kg (retired 1973)
SpaceX falcon heavy: 53,000 kg
Rods from God would be used on fixed installations with heavy anti ballistic missile defenses.
I suspect the first fictional use might have been “The Moon is a Harsh Mistress” 1966. The moon is a prison colony of earth that revolts. Instead of launching grain with oversize rail guns, they launch 200 ton cannisters of rocks at cities. ‘throw rocks, get sparks, throw big rocks get big sparks’ the sparks were about 10 kiloton blasts, if irc.
Remember Jarts? The Lawn Darts that are so horrifying to modern sensibilities? The US air force figured out that they could load up B-52’s with a version of those and drop from max altitude. In fact, that was the most cost effective way they figured out to stop a soviet armor invasion rolling into Germany. The tungsten darts would puncture the tanks top armor and kill everyone inside.
The lawn darts had no aiming system, they were to be simply dropped using regular ballistic aiming at advancing armor columns.
This and all the news surrounding the devaluation of Chinese currency, the selling of U.S. debt and any possibility of armed retaliation by either side for anything is a joint Chinese – U.S. psychological operation.
When the United States, under whatever pretext, institutes martial law, perhaps as early as September of 2015, it will use Chinese troops to assist in the mop-up. The United States and China are absolutely joined at the hip economically and militarily. Odierno was in China last year, or the year before conducting land war exercises. Please read the following blog: americainrevelation133.blogspot.com
Dear Robert, I don’t understand what you think this has to do with the subject of this article.
What an interesting Site! Thank you.
Even Intelligent comments, too!
I arrived here following a melodramatic article (and posts) from here:
http://www.naturalnews.com/050816_Tianjin_explosion_space-based_weapons_military_retaliation.html
which pointed to you.
I shall return as whatsis-name-said.
Himagain
Dear admin,
Been reading up a bit on this and major flaw in your reasoning seems to me the asumption you would need to shed the 7-8 m/s lateral velocity you need to stay in low orbit.
Why not put the weapon in (almost) geo synchronous orbit? We put satellites there all the time. This is way more out there of course (22.000 mi / 35.000 km) but that would mean:
– even more kinitic energy
– even with a small thruster pack / vectored ejection most places on earth would be targetable
– long long flighttime
You would have to build the rod of someting that can withstand the friction of a mach 12 entry.
You should also shape the rod for minimal friction. But given that? Why not?
It would be a non nuclear (hence allowed in all current space treaties) fixed site killer.
Non stopable. Non detecable.
Take out that north korean or iranian nuclear site if you have to without risk for your own military.
Or imaging an orbital strike on that fleet in the harbour.
Yoy would only use it on non mobile high value assets which you need to kill stealthy / deniable or which would be to costly to kill by other means.
Expensive? Not much more than many satellited already up there, but if i where in the pentagon?…. i would have it sitting there right now.
Even a dozen “shots” would be the option to quietly difuse a war situation or the need to go to war.
And if the us does not put it up there, one of the other spacepowers surely will. Imagine the chinese being able to pick off the white house or the pentagon. Or a carrier at anchor.
I think strategy wise it would give the us a valid option when dealing with rogue regimes with nasty assets. Kill missile sites. Nuclear plants, the dictators summer house etc.
Much tech is already there and off the shelve. I realy dont think its that weird and far fetched.
Just my 2 cents
Dear Edwin, thank you for your comment. Unfortunately I am not in agreement with your reasoning that a geosynchronous equatorial orbit (GEO) is an advantageous location to base these weapons.
Firstly, as I point out in the article, the weapon could only hit targets on or near the Earth’s equator. Secondly, it still takes a substantial de-orbit system to “stop” the projectile and make it fall to Earth (it would take less energy to send the the weapon to the Moon from GEO than it would to make it fall back to Earth). By the way I estimate it would take about 3 hours (at minimum) to fall (so targets could be evacuated or moved if they knew the weapon was on its way).
I do not understand why you think there is a military advantage to basing a kinetic energy projectile in orbit- ignoring politics, launching the same projectile on a missile from the Earth’s surface is more effective.
I remain unconvinced that this concept is viable at all.