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Sailing Off To The Stars

Sailing Off To The Stars

Sick and tired of NASA passing their beautiful country off as some intergalactic backwater, Finnish scientists think they’ve come up with a new, faster, cheaper, more efficient type of spacecraft – the space yacht.

Using solar wind, space yachts might be able to sail to Pluto in as little as four years; by comparison it took Voyager II twelve years to reach Neptune, which is on average a billion miles closer to the sun than Pluto.

The solar wind is a high speed plasma stream blowing outwards from the Sun, travelling between 300 to 800 km/s (about 1/1000th of the speed of light). It powers the aurora and governs space weather. However, it only exerts about 0.2 grams per square kilometre of pressure, which is pretty pathetic in the grand scheme of things.

Using such weak dynamic pressure for pushing a spacecraft requires a very large area sail, much larger than can be provided by a solid surface. Therefore the space yacht uses something a bit different: electric sails.

The electric sail is formed by an electric field existing around a thin, charged tether whose voltage is maintained by an onboard solar-powered electron gun. A 20-km long tether made of wire which is thinner than human hair fits in a small reel, but effectively provides a square kilometre of sail when stretched out in space and charged.

Scientific analyses, published today in the journal Annales Geophysicae, suggest that a lightweight yacht could reach speeds in the range 50-100 km/s (10-20 AU/year). At such high speeds one could fly out of the heliosphere and into interstellar space in less than 15 years. Because the electric sail needs no propellant or other consumables, it might also provide cheap transportation of raw materials such as water mined from asteroids and used for in-situ fuel making at high Earth orbit.

More stellar science:
 - News - The blob from outer space
 - Spoof - Custard proves space threat
 - News - Planets, planets everywhere
 - News - Global warming threat to the Hubble Telescope

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31 Dec 2008
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