OTHER WEAPONS in space

Lasers and kinetics are standard reference weapons, and for good reason. All other proposed weapons suffer from serious problems which render them ineffective compared to lasers and kinetics.

The most common alternative weapons described for space warfare are nuclear in nature. There are several myths about nuclear weapon use in space, the most common of which is that they are ineffective if not in contact with the target. The logic behind this theory is that in the atmosphere, most of the damage comes from the shockwave, which obviously cannot propagate in space. An alternative is that the damage will be inflicted by the plasma that used to be the device casing. The flaw is that the shockwave is not a property of the device itself, but instead results from the absorption by the air of the X-rays emitted by the device. The superheated air then expands and produces the shockwave. In space, the X-rays are not absorbed and instead go on to damage the target directly. They still obey the inverse square law, and are not likely to be effective against mass objects such as spacecraft beyond a few kilometers, depending on the yield of the device. This makes them essentially point-attack weapons, given the scale at which spacecraft maneuver.

However, there is another mechanism by which nuclear weapons do damage in space, namely radiation poisoning of the crew. Even a 1 kT nuclear weapon will inflict a lethal dose of radiation on an unprotected human out to about 20 km, depending on the type of weapon. Larger weapons will have greater lethal ranges, scaled with the square root of weapon yield. It is possible to armor against this radiation, reducing the lethal range by an order of magnitude or more. All spacecraft will have some radiation shielding because of the environment they operate in, although neutron radiation (probably the biggest killer) generally does not occur in nature. Civilian ships are thus likely to be far more vulnerable than military ones to nuclear weapons killing their crews, unless they themselves are nuclear-powered and manage to face their shadow shield towards the initiation.

It has been suggested that the great lethality of the radiation against the crew is likely to make enhanced-radiation weapons (commonly known as neutron bombs) the nuclear weapons of choice in space. This might well be the case, particularly as soft X-rays (such as might be produced by nuclear weapons) are significantly easier to shield against than the neutrons emitted by nuclear weapons, particularly the fusion neutrons produced by an enhanced-radiation weapon. The vulnerability of the crew to nuclear weapons is another factor that would make drones attractive, as electronics are easier to harden and generally more resistant to radiation.

The biggest disadvantages of nuclear weapons are their size and short range. Even the smallest of modern nuclear weapons are considerably larger than the SCODs described above, which makes them easy to detect and target, given that their destruction would logically take priority over that of more typical kinetics. At the same time, the nuclear weapon has to get to within a few kilometers, virtually touching the target. Given typical closing velocities, a fraction of a second is not going to significantly improve survivability vis a vis a typical kinetic. And a kinetic of the same size as the nuclear weapon (100 kg or more) is almost as lethal against a typical target. This ignores the questions of cost, which is almost certainly far higher for a nuclear weapon then an equal mass of kinetics, and of politics. Many people go into a frenzy whenever they hear the word ‘nuclear’, and would likely oppose the deployment of such weapons. Pushing said deployment through would require political and fiscal capital that might be better spent on conventional weapons.

Possibly the best use of nuclear weapons is in a defensive role. A typical kinetic will be quite vulnerable to surface and sensor damage, not to mention the relative lack of defenses against kinetics. Even then, squeamishness about nuclear weapons might well prevent their use.

The use of the X-rays from the device to pump a laser is also a common suggestion, most notably used in David Weber’s “Honor Harrington” series. The same drawbacks that apply to conventional nuclear weapons apply to these devices, though to a lesser extent. Much of the information regarding this concept is classified, which has led to conflicting views of its effectiveness. Depending on the source, the effective range is between 100 km and several thousand kilometers. Particularly at the lower end of this range, the utility is questionable. The device gains a few seconds of standoff, but still has the other disadvantages of conventional nuclear weapons. At longer ranges, particularly with low-end defenses, the idea becomes feasible.

There are two possible drawbacks to the use of nuclear weapons in orbit. The first is the well-known High-Altitude ElectroMagnetic Pulse (HEMP) generated when a nuclear weapon is detonated in the upper atmosphere. This results from the interaction between the products of the bomb, and both the Earth’s atmosphere and the Earth’s magnetic field. In deep space, neither would exist, removing the HEMP. HEMP is relatively easy to protect against, adding between 5 and 10% to the price of military electronic gear. High-quality civilian surge protectors are also adequate shielding, though low-quality models have problems dealing with the rate at which the pulse occurs. Any spacecraft will almost by definition be hardened against such effects. That said, the effect does exist, and would be a consequence of orbital nuclear weapon use.

The second drawback is the lesser-known Argus Effect, in which charged particles are trapped by the Earth’s magnetic field and form artificial radiation belts, damaging or destroying satellites. These particles are mostly electrons, and tend to cluster between 1000 and 2000 km altitude. They pose a threat similar to a greatly-enhanced Van Allen Belt, and would reduce the operational lives of satellites. There is a possibility that the belts could be used as a defensive weapon, but establishing them would mean sacrificing a large portion of one’s orbital (and quite possibly planetary) infrastructure. It is also possible that an “Argus Blockade” could be implemented. This would be the intentional creation of such an effect by an attacker, intended to impair the defender’s space infrastructure and prevent him from rebuilding quickly. The effect persists for a month or so before fading back to levels that are unlikely to impair space operations.

EMP weapons have occasionally been suggested for space use. These use some non-nuclear method to generate an EMP, hopefully disabling the target’s electronics. The generation of such a pulse requires a large amount of power, which can either be generated by high explosives (most useful in a missile) or large capacitor banks, which are far better suited for shipboard use. There are two major problems with this concept, however, which will likely limit its use. The first is that any EMP will be generated using microwaves or radio waves. As discussed in Section 7, diffraction is greater for beams with longer wavelengths. This limits the range of any EMP weapon, which is hardly desirable given the ranges at which space combat is likely to occur. The second is that there are a number of natural effects encountered in spaceflight that are similar to EMPs. Solar storms in particular can produce induced currents in much the same manner, requiring spacecraft to be hardened against them. This hardening would also be effective against EMPs, requiring massive amounts of power to have any chance of working. The only really practical use for EMP weapons might be during hostile boarding missions against civilians or disabled warships. A civilian ship is likely to be somewhat less hardened then a military vessel, and the boarding ship can get very close without getting shot to pieces by the target.