The Outer Space Treaty was signed in 1976 by one hundred and seven countries. Among its provisions is a ban on putting any nuclear, biological, or chemical weapons in Earth orbit. Of course there is the problem of being able to actually know exactly what is being launched into orbit by different countries and private firms. For all we know, there could be many nuclear, biological, or chemical weapons in Earth orbit right now ready to be used at a moment’s notice. But setting aside that issue, is there any way that destruction could be rained down on targets on Earth from orbit that do not involve the listed types of weapons? As a matter of fact, such an option does exist.
During the Vietnam war, the U.S. used a weapon called a “Lazy Dog.” These were two inch long steel pieces which had fins. Hundreds of these were dropped on Vietnam by planes. The principle of these steel projectiles is referred to as “kinetic bombardment.” These projectiles could be dropped from as low as three thousand feet and reach speeds of up to five hundred miles an hour. They hit with such force that they could punch through nine inches of concrete. These Lazy Dog projectiles gave rise to Project Thor.
The U.S. Air Force has a design for a very simple device that could be used as a weapon from orbit. A simple tungsten rod could hit a target on Earth with the destructive power of a nuclear warhead on an intercontinental ballistic missile. Project Thor was based on using a tungsten rod twenty feet long and one foot in diameter. The U.S. Air Force used the term “hypervelocity rod bundles” in a report. A magazine of these rods would be contained in a satellite. The rods would have fins and a small computer to control trajectory. These rods could be dropped from orbit a few thousand miles above the Earth. The rod would reach speeds of up to almost eight thousand miles per hour. When it hit, the rod would penetrate hundreds of feet into the earth. It would be able to destroy hardened bunkers or hidden underground military sites. Although the rod would cause a devastating explosion similar to a ground-penetration nuclear warhead, there would be no radioactive fallout.
One big problem with the whole idea of Project Thor was the fact that it costs about ten thousand dollars per pound to launch anything into space. At twenty four thousand pounds per rod, it would cost two hundred and thirty million dollars just to put one rod in orbit above the Earth. However, the cost of launching is going down rapidly as private space companies vie for launch business. The new Falcon Heavy lifter from SpaceX will be able to launch twice the payload at one third the cost when compared to the current heavy launch vehicles. That would reduce the cost of putting on rod in orbit to about forty million dollars. The cost of one Minuteman III ICBM in today’s dollars is would be about fifty seven million dollars. This means that one of the kinetic bombardment rods would be cheaper to launch into orbit that it would cost for a new Minuteman missile. Considering that the annual U.S. defense budge is approaching six hundred billion dollars, forty million dollars to put a rod in orbit is really a small part of the budget and quite feasible.
