"While many electronic devices can be shielded using the same techniques outlined in the section on EMP weapons, most sensors and high-gain antennas cannot be shielded without preventing them from performing their primary functions.
"A space-based HPMW weapon must have an antenna or array of phased antennas with an area measured in acres to point and focus its beam properly on terrestrial targets. The resources necessary to construct such huge structures could be expensive to lift into orbit, and difficult to assemble in the free-fall [ weightless s- MILNET] environment. Like the NPB, the HPMW weapon is a line of sight [ no mirrors - MILNET] device that must "see" its target before it can fire.
"The level of pulsed, electrical power required to produce weapon-level microwave fluxes is now becoming available (for ground-based systems). Compact, scalable laboratory sources of narrow-band, high-power microwaves have been demonstrated that can produce gigawatts of power for 10 to a few hundred nanoseconds [ more than adequate - MILNET] Ultra-wideband microwave sources are less well developed, but research in this area appears promising. A HPMW weapon should, however, be able to temporarily disrupt circuits and jam microwave communications at low power levels.
A space-strike HPMW system would consist of a constellation of satellites with very large antenna or arrays of antennas. The farther out in space the constellation resides, the fewer the number of satellites required. However, there is a corresponding increased requirement for more power and larger antennas. Another possibility is to overlap "spot" beams from many smaller HPMW satellites on each target, gaining the benefit of high power on centroid (but a very much larger combined spot) at the cost of satellite proliferation. A useful distributed HPMW weapon system of this type might resemble the Iridium or Teledesic constellation of LEO satellites [ communications satellite systems in Low Earth Orbit - MILNET] (many tens of hundreds of satellites, however, and the HPMWs would not be small satellites).
At low powers, the HPMW weapon system is fully capable of jamming communications when pointed at the opponents receiving stations or platforms, in addition to its obvious uses against an enemy's electrical and electronic systems at higher power levels. Since water molecules are also known to absorb certain bands of microwave frequencies, it is also possible a properly designed HPMW weapon system could be used to modify terrestrial weather.
Minute devices, if small enough, could be immune to HPMW weapons simply because microwave frequencies cannot couple enough energy into them to cause damage. ..Optical devices are inherently immune to microwave radiation, although the sections of optical circuits where light is converted back into current still have to be shielded.
The HPMW weapon system is not deemed suitable for space-force applications in 2025." [ Only if you ignore the possibility of hovering over facilities -- this weapon system could be quite effective against non-hardened manufacturing facilities, hideouts, or opponent's bedrooms - MILNET]
Kinetic Energy Weapons
The Kinetic Energy Weapon uses extremely high velocities to "penetrate" its targets with catastrophic shock. A 30 meter object falling to earth will ablate as it reenters, but its impact is equivalent to a 10 KT nuclear weapon and does not have the radiation effects. Smaller devices have smaller impacts, but far exceeding a typical explosive warhead. As the text below describes, there are two types, KEP which travel at above Mach 3, and HP which travel at around Mach 25.
"Kinetic Energy Weapons come in two classes related to their velocity -- The Kinetic Energy Penetrator (KEP) and the Hydrodynamic Penetrator (HP).
KEP
The KEP has a maximum impact velocity of 3 kilofeet per second (kfps), about the maximum speed of an SR-71 blackbird. The KEP destroys the target by shattering it with an enormous blow. SInce some areas of a target are more vulnerable to shattering blows than others, precise targeting is necessary for an effective KEP.
HP
The HP has a minimum impact velocity of 8 kfps. When a penetrator strikes a target at this extreme velocity, both target and penetrator react to the collision as if they were fluids (their behavior described by hydrodynamic equations of motion). The impact attacks the molecular composition of the target, spreading dense impact shocks at enormous speed.
"A nagging problem for KEW systems is the heat and shock generated on reentry. This can effect the precise delivery of the weapon. An exciting new concept has been proposed that promises to ameliorate this problem. By concentrating a laser beam in the area immediately in front of the hypervelocity KEW, it is possible to create a laser-supported detonation wave (called an "air spike") that partially shields the KEW. The air spike transforms the normal conical bow shock into a much weaker, parabolic-shaped oblique shock. Researchers estimate that a properly designed air spike could decrease the effects of shock and heat on a hypervelocity object by over 75 percent (making Mach 25 seem like Mach 3)."
Finally, an interesting variation the more conventional KEW concept involves the use of meteorites as a weapon.
"Naturally occurring meteorite at least the size of large houses (necessary to survive drag-induced heating in the atmosphere) could be intercepted in space and redirected to a terrestrial target. If done with sufficient stealth and subtlety, the impact could even be "plausibly denied" as a natural occurrence. Meteorites 30 feet in diameter could be counted on to generate nuclear weapons sized explosions (20 kilotons), but without the lingering radiation.
Meteors can be hundreds of magnitudes more deadly than the KEW. However, there are several significant shortfalls to meteorites as weapons. They are hardly a timely weapon -- the war fighter must patiently wait for nature to deliver his "ammunition". [ or you could go out and mine asteroids and have them handy nearby - MILNET] The uneven shape and heterogeneous composition of meteorites makes it highly unlikely that they can be guided precisely to a target. [ or you could carve them into nice shapes after/as you mine them - MILNET] Since it is also impossible to predict how much of the meteorite will survive the fall from space, meteors are best classified as an area weapons with a very uncertain radius of effect. [ - just drop fifty on the mountain range where Bin Laden is thought to be hiding - MILNET]
A few hundred KEW "storage containers" placed in LEO would make the timeliness and responsiveness very high (within a few minutes). Precision and reliability would also be high. Total destruction would be the only choice, unless used as a demonstration of power."
