As implied above, another factor that has affected the prospects of space's weaponization has been the extremely high costs involved. The root of this problem lies in the great expense of placing any objects into space, but it is exacerbated by the fact that orbiting objects are difficult to maintain and modernize, particularly if there are changes in technical capabilities and/or targeting information. But perhaps the most damaging factor in regard to cost is the fact that orbital physics require that any militarily significant constellation of interceptors placed in space must be deployed in considerable numbers, given the "absentee problem"--i.e., the fact that a harmful attack could be undertaken by an adversary at an "inconvenient" time in the orbit of any defensive system.

One recent report, for example, has estimated that for a constellation of space-based weapons for use in "global strikes" against ground targets within 45 min, the requirement is for nearly 50 individual interceptors to cover even a limited swath of the Earth's land mass.12 The report concludes that "acquiring the capability to attack a ground target within 45 minutes would be many tens of times more costly if done from space than from the ground". Of course, for an anti-ASAT system, the requirements are much higher, since an hour could mean the difference between defense and irrelevance. For this reason, the start of any arms race in space will involve extremely high costs. In addition, the deployment of such systems puts assets in space on hair-trigger alert, creating serious risks of misidentification of targets. Such events could lead to the destruction of property, inadvertent loss of life, or accidental war.

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Moltz, James Clay. "Protecting Safe Access to Space: Lessons from the First 50 Years of Space Security." Space Policy. Vol. 23 (November 2007): 199-205. [ 12 quotes ] [ page 203 ]