posted on Jun, 18 2004 @ 08:33 AM
AND THE STAR WARS PROGRAM
If a nuclear attack were launched on America, it could involve hundreds
of missiles carrying thousands of warheads, each travelling at up
to 4 miles a second towards targets they would reach within 30 minutes
of launch. To protect themselves, the US have therefore developed
their Strategic Defense Initiative (SDI) or 'Star Wars' program.
A major part of this program is to develop lasers that will shoot
down enemy missiles within five minutes of launch. If it was left
any later than this, then defense becomes much more difficult because
the missile releases up to ten seperate warheads and many decoys,
greatly increasing the number of targets that have to be hit.
Lasers destroy their targets by directing onto them an intense
beam of energy which travels at the speed of light - 186,000 miles
a second. The simplest method of destruction is to focus a beam
of infrared radiation on a missile so that it burns a hole in the
rocket casing, causing fuel to escape so stopping the missile from
reaching orbit. Another possiblity is directing the beam to disrupt
the rocket's electronic guidance system.
The US are developing a chemical laser in which hydrogen and fluorine
react together to form hydrogen fluoride, which is a corrosive gas
or liquid which can be made to release a powerful burst of infrared
radiation. The laser is focused and aimed by prisms and mirrors.
A chemical laser of sufficient power, at least 25 megawatts, could
destroy a missile almost 2,000 miles away.
The lasers would attack their targets from battle stations in
space, a few hundred miles above the Earth. However, a total of
about 100 stations would really be needed to give the US the possibility
of complete protection, and getting that many in space would dwarf
any previous space project.
Just the hydrogen fluoride needed to fuel the lasers would weigh
about 2000 tons! Think of the costs for that kind of payload. How
would such a project be funded? A possible alternative to that might
be to base the lasers on land. The difficulty then though is that
the atmosphere would disperse the laser beam, making it impossible
to focus on the missile's skin. Putting the lasers on top of high
mountains would reduce distortion, obviously because their would
be less atmosphere to penetrate. Advanced optical techniques designed
to counteract the dispersive effect of the atmosphere may also help.
Even so, no more than a tenth of the power of the laser could
be expected to reach the target, which means that the lasers fired
from Earth would need to be very powerful. They would probably need
to have the power of around 400 megawatts each. This is the equivalent
electricity consumption of a medium-sized city, and 1000 times more
powerful than any laser known to exist today.
Mirrors would have to keep the lasers locked onto the missile
for several seconds before it would be destroyed. Even if this were
achieved, the enemy could probably still defeat the laser by putting
a heat shield around the missile or by making it spin so that the
beam could not be focused on the same spot long enough to burn a
hole. The Star Wars program has also been developing lasers which
produce X-rays rather than a beam of light. These X-rays are produced
in a single pulse rather than a continuous beam (a pulse laser).
The source of the X-rays is a small nuclear explosion. When the
pulse of X-rays hits the enemy missile they are absorbed by it's
skin, vaporising it and blowing the missile apart. Because X-rays
are rapidly absorbed by the atmosphere they would also have to be
fired from space when both the laser, and the missile it was attacking,
had risen above the atmosphere. This is at least 50 miles above
The idea is not to station the lasers permanently in space, but
to launch them only when satellite observations show that an enemy
attack is already under way. The X-ray lasers would be launched
from submarines, and would then be quickly boosted into orbit where
they would be aimed and fired accordingly and automatically.