Space Weapons Earth Wars

This summary of a report prepared for the US Air Force by the Rand Corporation describes the attributes of space weapons and "sets out a common vocabulary for future discussions" about them. It also works to dispel misconceptions about space weapons so that discussion can be as fact based as possible.

Find the summary here:

The full version can be downloaded here if you're interested:


It is important to understand that “space-based weapons” generally

includes several distinct classes of weapons:

• directed-energy weapons

• kinetic-energy weapons against missile targets

• kinetic-energy weapons against surface targets

• space-based conventional weapons against surface targets.

Directed-energy weapons, which destroy targets with energy transmitted at the speed of light over long distances, are in class of their own. The other three weapon types destroy targets by delivering mass to the target using either the kinetic energy of their own velocity and mass or the stored chemical energy of conventional explosives to destroy the target. Each type of weapon operates in different ways, is suitable for different kinds of targets, has different response

times, and requires different numbers of weapons in orbit to achieve

the degree of responsiveness required to reach a particular target

when needed. Table S.1 summarizes these distinctions.


Directed-energy weapons include a range of weapons from electronic jammers to laser cutting torches. While jammers need to transmit only enough power to compete with the targeted receivers’ intended signals, destroying ballistic missile boosters would require developing and deploying lasers with millions of watts of power directed by optics on the order of ten meters in diameter. Directed-energy weapons could destroy targets on or above the earth’s surface, depending on the wavelength of the energy propagated and the conditions of the atmosphere, including weather.

Although the energy a laser delivers propagates at the speed of light, the laser has to hold its beam on a target until energy accumulates to a destructive level at the target. After destroying a target, it can retarget as quickly as it can point at the next missile, should it have sufficient fuel. When defending against a salvo of missiles, the laser will only be able to destroy a certain number of missiles while they are in their vulnerable boost phase. That number will depend on the laser’s distance from the launch position and the hardness of the missile target. The farther the laser weapon is based from the target and the harder the material of the target, the fewer missiles the laser will be able to destroy during boost phase. Because the distance of laser satellites from missile launch points fluctuates in a predictable way, an opponent launching missiles will be able to choose to launch at times that allow the maximum number of missiles to penetrate the


Kinetic-Energy Weapons Against Missile Targets Above the Atmosphere

Kinetic-energy weapons come in two types: those designed to destroy targets outside the earth’s atmosphere and those that can penetrate the earth’s atmosphere. The first type, described here, could conceivably provide an additional layer of defense against targets that leak through the laser weapons’ boost-phase defense. They would destroy targets using the kinetic energy of high-velocity impact and would require very little weapon mass. As with directed energy weapons, the short response time for missile defense would require dozens of weapons in space for each one within reach of a

potential target.

However, kinetic-energy weapons for use against missile targets are handicapped in their ability to respond quickly to the missile threat. They are not able to engage targets below 60 km because the interceptor needs to stay out of the atmosphere. This may mean that the intercept could only occur after the missile’s boost phase, when multiple warheads and decoys may have been deployed, creating the potential for saturation an order of magnitude greater than for boost-

phase defense with directed-energy weapons.

Kinetic-Energy Weapons Against Surface Targets

Space-based kinetic-energy weapons for surface targets also destroy targets by using their own mass moving at very high velocities. Unlike weapons that engage targets outside the earth’s atmosphere, these must be large enough to survive reentry through the earth’s atmosphere with a speed high enough to be destructive. To preserve accuracy and energy through reentry, they have to attack targets at steep, nearly vertical trajectories. This would mean having either a great many weapons in low orbits to have one within reach of a target whenever needed or a smaller number at higher orbits with longer times to reach targets. A reasonable high-altitude constellation would place about six weapons in orbit for each target to achieve response times of two to three hours from initiation of the attack to destruction of the target.

The effort required to deliver one of these weapons to orbit and then to a target would be similar to that required for a large intercontinental ballistic missile (ICBM). Such weapons could be effective against stationary (or slowly moving) surface targets that are vulnerable to vertical penetration of a few meters, such as large ships, missile silos, hardened aircraft shelters, tall buildings, fuel tanks, and munitions storage bunkers. Because of their meteoroidlike speed entering the atmosphere, these weapons would be very difficult to defend against.

Although they would be of little interest to the United States because it already has weapons that are effective against this class of targets, kinetic-energy weapons could be desirable for countries that seek global power projection without having to duplicate the U.S. investment in terrestrial forces.

Space-Based Conventional Weapons Against Surface Targets

Space-based conventional weapons would inherit their accuracy, reach, target sets, and lethality from the conventional munitions they deliver. Such weapons could engage a broader range of targets than kinetic-energy weapons, including maneuvering targets and more-deeply buried targets. They could use “old” technology. The systems used to deliver them from space might resemble those developed for the return of film and biological specimens from orbit in the 1960s.

The effort to deliver conventional weapons to orbit and then to a terrestrial target is similar to that for space-based kinetic-energy weapons, but conventional weapons are much more responsive. They would take about 10 minutes from weapon release to deployment in the atmosphere, plus whatever time the conventional munitions need to reach the target after that. Small, precision weapons would be preferred for space basing, since their launch costs are higher than the costs of delivering them from aircraft or ships. It would take about six weapons in orbit to keep one within 10 minutes

of a target on earth.

Offer your thoughts on the potential of space weapons here:

Featured Posts