Sender: enrico@uniroma3.it
Message-ID: <3EC18549.6C75F245@uniroma3.it>
Date: Tue, 13 May 2003 16:52:41 -0700
From: Enrico <valbones@uniroma3.it>
Organization: uniroma
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Subject: beamed-energy propulsion
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Status: RO

http://www.dd.chalmers.se/~f99erjn/FYPRI-projekt/beamedenergy.html

Beamed-energy propulsion

As previosly said, carrying the source of power can be a major problem
for a spacecraft since it easily becomes very heavy, especially in a
chemically driven rocket. A novel way of
solving this problem is to simply leave the power source behind and
transfer the power to the spacecraft via a laser or microwave beam. The
beam would then originate from a stationary
source on the Earth. In the future it might be possible to put such a
source in space, and perhaps let it be powered by Solar energy.

One way of turing this beam into thrust for launch from earth would be
to let the so called lightcraft reflect and focus pulses of light, thus
heating the air and making it expand
explosively, pushing the craft in front of it. When the craft reaches
altitudes where air is scarce, it would turn to conventional technology,
propelling it to the final orbit.

At present, this method appears to be the one that could cut the costs
of putting a paylod into orbit most drastically. Unfortunately, it is
best suited only for small payloads, such as small
satellites and will probably never be able to carry such things as a
crew to orbit.

Advantages

Does not need to carry its power source with it, thereby saving a
significant amount of weight. Also, the prospects that this method will
be cheap are very good. In fact, it seems to be the
cheapest method in sight for a long time.

Disadvantages

Most lightly only suitable for small payloads such as small satellites.
The dependence of a stationary power source limits the possible
manouvres and directions of travel. Requires the
development of methods to create much more intensive laser and/or
microwave beams.