In 1983, President Ronald Reagan championed the Strategic Defense Initiative, better known as “Star Wars.” SDI was a Ballistic Missile Defense (BMD) system famous for using lasers mounted on large planes to shoot down Soviet and Chinese ICBM’s during the boost phase (though directed energy weapons were not the only technology in development). The laser system did not work then; however, we can do it now and do it even better. We can put those lasers in space.
There are several benefits to putting a network of satellites equipped with lasers in Low Earth Orbit for BMD.
Shoot Down during Boost Phase: With modern MIRV ICBM’s it is imperative to shoot the missile down during Boost Phase when the missile is essentially a single target. Once the final stage is at the apoapsis of its trajectory, the faring can be jettisoned and the warheads separated from the launch vehicle. With some technical work ahead of time, the fairing can be cut and designed so that it will also reenter the atmosphere while appearing to be several warheads on enemy sensors. Now there are potentially dozens of targets requiring shoot down instead of one.
Readiness: Although lasers on planes could also shoot down an ICBM during boost phase, they would constantly need to be circling outside of an enemy state’s borders waiting to intercept. On the other hand, a network of satellites, despite requiring more setup, would always be on station and potentially orbiting right over an enemy state.
Effectiveness and Range: One of the largest problems with using lasers in atmosphere is that the atmosphere itself acts as a lens and distorts the beam, thus weakening it at long range. Naturally, this is not a problem in space. A laser fired from a satellite would only begin to distort as it entered the atmosphere.
Cost: Although a satellite based laser BMD system would be expensive to completely produce, the actual cost per use would be very low, as evidenced by the Navy’s Laser Weapon System (LAWS)