Sailing Starry Seas
01/08/2005 . Source: Mark R. Leeper 
Early fantasies of space travel envisioned ships pulled by teams of birds or versions of balloons, says Mark. Some fantastic accounts of voyages into space pictured it being on flying ships like the sailing ships in the seas. They were supposedly being propelled by winds in space. Buy Solar sails in the USA - or Buy Solar sails in the UK  [Postscript placed at the beginning: As some of you may know, this attempt
ended in failure when the Russian missile malfunctioned. Hopefully this is only
a delay. -mrl]
Of course such things as space ships pulled by sails would not really work.
Not until now. I write this on Tuesday, June 21, 2005, which may well become
a historic date. Not only is it the day of the year that we get the sunlight
the longest; it is also a day when we launch an elegant spacecraft that will
have a bold new use for that sunlight. Today is the launch of a new design of
spacecraft that has been the subject of science fiction, but only that, for
years.
The Cosmos 1 one hopes will be the first working solar-sail. That is, it is
a craft that uses as its power only the sun on a giant solar sail. Among other
things it does it adds a great deal of prestige to the concept of Carl Sagan's
Planetary Society. When he was alive, Sagan championed the solar sail and his
widow, Ann Druyan, continues to champion it after his death. Today is something
of a triumph for Sagan. The unmanned craft weighs in at only about 220 pounds
and consists of a central fuselage and eight triangular sails that will project
out of the core to a length of about fifty feet.
As if that was not dramatic enough, the means of its being placed in orbit is
also spectacular. A Russian Delta III submarine in the Barents Sea will launch
a Volna missile carrying the Cosmos I. This missile has been converted into
a two-stage rocket that will carry the Cosmos I into space orbit. On Friday,
the day of this notice, the Mylar sails will open up and catch the light of
the sun.
Mylar is the light, thin, shiny material that party balloons are frequently
made of. Sunlight may not seem to exert a whole lot of force, but it is enough
to push the Cosmos I. Force is mass times acceleration. The mass has been kept
as small as possible. Unfortunately the force is not very large either so the
acceleration will be small. But the craft will be in space, five hundred miles
up, where there is no atmosphere to slow it.
It will just sit there in orbit very slowly accelerating. It will gain about
four miles per hour each hour. After a while that will be enough speed to do
something with. Among the things it will do will be to achieve a higher orbit.
Even there the mission of this craft will be limited. The life of the struts
for the sails is measured in weeks so this little craft will not go very far.
The pressurized gas that keeps Cosmos 1's ribs in place will probably leak eventually.
The ship's orbit will decay and it will burn up in the atmosphere. A more durable
version might go to Mars or considerably beyond.
This is not the first solar-sail in space. The Japanese have already sent up
two to test sail deployment, but not to actually use the propulsion. This is
actually the second attempt by the planetary society. A previous attempt to
send up two-sail model failed to separate from the delivery rocket and crashed
in Kamchatka, Russia. This technology may be somewhat limited. Its relation
to rockets is sort of like the relation an air balloon has to a powered airplane.
It is more graceful, but less powerful. At least if the sails are strong enough
a solar-sail does not run out of fuel. Ever. But the sail-ships are getting
attention. Both NASA and the Japanese Aerospace Exploration Agency are working
on solar-sail projects. A spokesman for The Planetary Society says that they
will not be able to compete with NASA for long and that the large scale projects
are going to be NASA's in the future. The competition between the Planetary
Society and NASA could hardly be friendlier
since each is hoping the other will be successful. But being privately funded,
the Planetary Society cannot long compete. The price of this experiment is about
four million dollars.
Because the Cosmos I has an orbit of 78-degree inclination it should be visible
in the sky from most of the earth at one time or another. There is not much
north of 78-degress north or south of 78-degrees south.
"Solar sailing is really the only known technology that could potentially take
us to the stars one day, because it does not have to carry fuel with it and
because it can keep accelerating-- even at incredible distances," said Amir
Alexander of the Planetary Society.
Mark R Leeper 
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