A kinetic bombardment or a kinetic orbital strike is the hypothetical act of attacking a planetary surface with an inert projectile, where the destructive force comes from the kinetic energy of the projectile impacting at very high velocities. The concept originated during the Cold War.
The typical depiction of the tactic is of a satellite containing a magazine of tungsten rods and a directional thrust system. When a strike is ordered, the satellite would brake one of the rods out of its orbit and into a suborbital trajectory that intersects the target. The rod picks up speed as it approaches periapsis and the target due to gravity, picking up immense speed until it begins decelerating in the atmosphere and reaches terminal velocity shortly before impact. The rods would typically be shaped to maximize terminal velocity. In science fiction, the weapon is often depicted as being launched from a spaceship, instead of a satellite.
Kinetic bombardment has the advantage of being able to deliver projectiles from a very high angle at a very high speed, making them extremely difficult to defend against. In addition, projectiles would not require explosive warheads, and—in the simplest designs—would consist entirely of solid metal rods, giving rise to the common nickname "Rods from God". Disadvantages include the technical difficulties of ensuring accuracy and the prohibitively high costs of positioning ammunition in orbit.
The Outer Space Treaty prohibits weapons of mass destruction in orbit or outer space. However, the Outer Space Treaty only prohibits nuclear, biological, and chemical weapons. Since the most common form of kinetic ammunition is inert tungsten rods, in most cases, kinetic bombardment remains legal.
Real life concepts and theories
During the Vietnam War, there was limited use of the Lazy Dog bomb, a steel projectile shaped like a conventional bomb but only about 1" long and 3/8" diameter. A piece of sheet metal was folded to make the fins and welded to the rear of the projectile. These were dumped from aircraft onto enemy troops and had the same effect as a machine gun fired vertically. Observers visiting a battlefield after an attack said it looked like the ground had been 'tenderized' using a gigantic fork. Bodies had been penetrated longitudinally from shoulder to lower abdomen. This idea is similar to the concept of bullets not being fired out of a weapon, but having enough velocity to impact a human body with enough force to kill.
Project Thor is an idea for a weapons system that launches kinetic projectiles from Earth's orbit to damage targets on the ground. Jerry Pournelle originated the concept while working in operations research at Boeing in the 1950s before becoming a science-fiction writer.
The system most often described is "an orbiting tungsten telephone pole with small fins and a computer in the back for guidance". The system described in the 2003 United States Air Force report was that of 20-foot-long (6.1 m), 1-foot-diameter (0.30 m) tungsten rods, that are satellite controlled, and have global strike capability, with impact speeds of Mach 10.
The time between deorbit and impact would only be a few minutes, and depending on the orbits and positions in the orbits, the system would have a world-wide range. There would be no need to deploy missiles, aircraft or other vehicles. Although the SALT II (1979) prohibited the deployment of orbital weapons of mass destruction, it did not prohibit the deployment of conventional weapons. The system is not prohibited by either the Outer Space Treaty or the Anti-Ballistic Missile Treaty.
The idea is that the weapon would naturally contain a large kinetic energy, because it moves at orbital velocities, at least 8 kilometers per second. As the rod would approach Earth it would necessarily lose most of the velocity, but the remaining energy would cause considerable damage. Some systems are quoted as having the yield of a small tactical nuclear bomb. These designs are envisioned as a bunker buster. As the name suggests, the 'bunker buster' is powerful enough to destroy a nuclear bunker. With 6–8 satellites on a given orbit, a target could be hit within 12–15 minutes from any given time, less than half the time taken by an ICBM and without the launch warning. Such a system could also be equipped with sensors to detect incoming anti-ballistic missile-type threats and relatively light protective measures to use against them (e.g. Hit-To-Kill Missiles or megawatt-class chemical laser).
In the case of the system mentioned in the 2003 Air Force report above, a 6.1 m × 0.3 m tungsten cylinder impacting at Mach 10 has a kinetic energy equivalent to approximately 11.5 tons of TNT (or 7.2 tons of dynamite). The mass of such a cylinder is itself greater than 9 tons, so the practical applications of such a system are limited to those situations where its other characteristics provide a clear and decisive advantage—a conventional bomb/warhead of similar weight to the tungsten rod, delivered by conventional means, provides similar destructive capability and is far more practical and cost effective.
The highly elongated shape and high mass are to enhance sectional density and therefore minimize kinetic energy loss due to air friction and maximize penetration of hard or buried targets. The larger device is expected to be quite good at penetrating deeply buried bunkers and other command and control targets.
The weapon would be very hard to defend against. It has a very high closing velocity and small radar cross-section. Launch is difficult to detect. Any infrared launch signature occurs in orbit, at no fixed position. The infrared launch signature also has a much smaller magnitude compared to a ballistic missile launch. One drawback of the system is that the weapon's sensors would almost certainly be blind during atmospheric reentry due to the plasma sheath that would develop ahead of it, so a mobile target could be difficult to hit if it performed an unexpected maneuver. The system would also have to cope with atmospheric heating from re-entry, which could melt non-tungsten components of the weapon.
In science fiction
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In the mid-1960s, popular science interest in orbital mechanics led to a number of science fiction stories which explored their implications. Among these was The Moon Is a Harsh Mistress by Robert A. Heinlein in which the citizens of the Moon bombard the Earth with rocks wrapped in iron containers which are in turn fired from an electromagnetic launch system at Earth-based targets.
In the 1970s and 1980s this idea was refined in science fiction novels such as Footfall by Larry Niven and Jerry Pournelle (the same Pournelle that first proposed the idea for military use in a non-fiction context), in which aliens use a Thor-type system. During the 1980s and 1990s references to such weapons became a staple of science fiction roleplaying games such as Traveller, Shadowrun and Heavy Gear (the latter game naming these weapons ortillery, a portmanteau of orbital artillery), as well as visual media including Babylon 5's "mass drivers" and the film Starship Troopers, itself an adaptation of a Heinlein novel of the same name.
The re-purposing of space colonies for use in kinetic bombardment (referred as a "colony drop") is a frequent element of the Gundam franchise and is central to the plots of Mobile Suit Gundam: Char's Counterattack and Mobile Suit Gundam 0083: Stardust Memory.
A smaller "crowbar" variant is mentioned in David's Sling by Marc Stiegler (Baen, 1988). Set in the Cold War, the story is based on the use of (relatively inexpensive) information-based "intelligent" systems to overcome an enemy's numerical advantage. The orbital kinetic bombardment system is used first to destroy the Soviet tank armies that have invaded Europe and then to take out Soviet ICBM silos prior to a nuclear strike.
From the mid-1990s, kinetic weapons as science fiction plot devices appeared in video games. Appearing in Bullfrog Productions' 1996 Syndicate Wars as a player-usable weapon, it also featured prominently in the plot of Tom Clancy's Endwar, Mass Effect 2, "Call of Duty: Ghosts" Unnamed Kinetic Strike Weapon, Call of Duty: Ghosts Odin and Loki strikes, to name some.
The Warren Ellis comic Global Frequency (issue #12, "Harpoon", August 2004) featured the threat of kinetic spears, weapons designed to be dropped from satellites, heat up on re-entry, and strike the ground with the force of a tactical nuke, and as hot as the edge of the sun. Rather than being a weapon of war they were depicted as part of a 'die-back' protocol designed to reduce Earth's human population to a sustainable level.
In 2013 a kinetic weapon bombardment system consisting of tungsten rods in an orbiting platform, codenamed Project: Zeus, was featured in the movie G.I. Joe: Retaliation, where it destroys London. However, the movie misrepresented physics by claiming the rod would not be "launched" or "fired" but merely "dropped". If it were released without force it would orbit the Earth in the same manner as the platform itself. In order for a rod to fall straight toward the center of Earth it would need to be launched away from the station with a velocity equal in magnitude and opposite in direction from the orbiting station. This velocity would be in the range of approximately 7–8 km/s for satellites in low earth orbit (see Orbital speed#Tangential velocities at altitude for more information).
- Railgun (ground/navy, mach 10)
- Kinetic energy penetrator
- Relativistic kill vehicle
- Prompt Global Strike
- Brilliant Pebbles
- https://books.google.com/books?id=pjiuMbDxsJIC&pg=PA107&lpg=PA107&dq=%22brake+out+of+orbit%22&source=bl&ots=Uo1gpLSLUA&sig=XFplYY9iJuA6yNSQZee8Tr0C0RE&hl=en&sa=X&ved=0CCEQ6AEwAGoVChMImvqnjfqWxwIVyx0-Ch2jfgFU#v=onepage&q=%22brake%20out%20of%20orbit%22&f=false - The use of the work "brake" in this paragraph refers to the act of braking; the fact that by slowing the rod's orbital trajectory, the satellite can de-orbit it in order to drop it onto the planet below.
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