Defense Intelligence Reference Document State Of The Art And Evolution Of High-Energy Laser Weapons

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• Component vulnerability - All spacecraft have essential components which are
exposed and potentially susceptible to laser radiation. Solar panels, from either the
front or back, could be damaged or shorted. Cabling among the solar panels and
between the spacecraft and the panels could be damaged. If the mechanism which
keeps the solar panels pointed at the sun were damaged, then the panels couldn't
be rotated and would lose efficiency. Similarly, antennas used for communications
or navigation are susceptible along with their RF/power cables and the mechanisms
which keep them pointed. Many spacecraft use optical sensors to locate stars, the
sun, or the earth's horizon for navigation or attitude determination. The loss of any
of these types of sensors could significantly affect the spacecraft and could be
accomplished fairly easily by a medium-to-large earth-based laser weapon if the
spacecraft were in earth orbit or by a smaller laser system which was onboard
another spacecraft.
• Structural penetration - A unique vulnerability of manned spacecraft is the
requirement to maintain a suitable internal atmosphere. If the pressure-vessel
portion of the spacecraft were penetrated, even in a small area, it could prove fatal.
The design and operation of any spacecraft should consider these vulnerabilities if
damage from laser radiation is a concern. In addition to thermal modeling and careful
design/shielding, candidate components, materials, and surface treatments could be
tested for laser radiation susceptibility in government laboratories or independently by
purchasing commercial lasers.
Projection of Future HEL Weapon Capability
Chemical Lasers - Once the physical processes were reasonably well understood and
determined to be scalable, MW-class chemical laser systems were quickly achieved by
the late-1970s and still remain the sole source of that power level. Since then, the
technology has matured which resulted in marginal efficiency improvements with very
low probability major additional breakthroughs in this area. There are no first-
principles reasons why output powers could not have been brute-force scaled upward
by another decade using larger gain generators but a few practical reasons (in addition
to cost) precluded that happening:
• Efficient atmospheric propagation of 10+ MW chemical laser beams would have
required 10+ meter pointing telescopes which are unreasonable for any mobile or
portable (including ships) military applications.
• The only possible military applications which don't suffer atmospheric propagation
limitations are space-based however the weight, volume and consumption rate of
chemicals would cause this to also become unreasonable and unaffordable.
• There were better wavelength choices (and potential laser types) for conceivable
non-military applications such as power beaming to the moon or spacecraft in earth
orbit and laser assisted propulsion of spacecraft.
Solid-State and Free-Electron Lasers - The current (and probably foreseeable future)
thrust in laser development and power scaling should be expected in the area of
electrically powered lasers. This will probably be true whether the laser system is
earth-based or space-based. These include solid-state (slab & fiber) as well as FELs.
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