For use with Chapter 6
to the Stars
Posted April 11th, 2001
of years ago, Johannes Kepler made the suggestion that ships
could sail through space using "heavenly breezes" much like
ships do that sail across the sea using the wind. Because
there's a vacuum in space, there are of course no breezes
in space. However, there are winds - solar winds. Solar winds
are photons and particles that radiate out from the Sun. Scientists
at NASA's Jet Propulsion Laboratories (JPL) are developing
a way to harness these winds with huge solar sails.
sails need to be incredibly thin and lightweight to be easily
transported into space. The sails would be sent into space
in a small container and then deployed when their location
has been reached. The sails would then be propelled by photons
and microwaves. When the sails are deployed near Earth, which
is relatively close to the Sun, the powerful radiation from
the Sun will push the ship deep into space.
the ship traveled beyond the influence of the solar winds,
it could continue "coasting" at an incredibly high speed beyond
the solar system. Scientists calculate a ship propelled by
these sails could reach the nearest star in approximately
materials have been developed to make the sails. It uses a
special carbon composite that was developed by Energy Science
Laboratory in San Diego, California. The compound is strong
enough to resist the intense heat of the radiation in space
(up to 2,500 Kelvin) and being pelted by micrometeors, yet
thin enough to meet the lightweight requirements to send it
material was tested at JPL and at Wright-Patterson Air Force
Base in Dayton, Ohio. They were able to produce an acceleration
that was several times as powerful as the force of gravity.
sails could achieve speeds much faster than can be achieved
through traditional spaceflight. It would also be a source
of "fuel" - which is directed from outside of the ship - and
allow the ship to travel farther than is possible now.
Planetary Society, which was founded by scientist Carl Sagan
among others, plans to send a test probe into space that will
use this technology. Their craft will have 30-yard sails and
will cost about $4 million. If the test flight is successful,
perhaps in a few short decades, it might be possible to travel
beyond the solar system.
the Internet sites given here to research these space sails.
In a small group, build a model of these spacecraft and explain
it to the class.