Electric Solar Sail Technology Moving Forward, “Impossible To Create” Electric Sail Tether Produced

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The electric solar sail, or ESAIL, is a ‘sail’ that provides propulsion for a spacecraft simply by using the solar wind, no fuel whatsoever. Invented only very recently, in 2006, a prototype has not yet been created. But now one of the primary limitations have been overcome, the production of the 1-km-long ESAIL tether, something which had been considered impossible by most global experts in ultrasonic welding.


The technology, which works by creating a electric field that deflects solar wind protons and takes momentum from them, offers the future possibility of fast, cheap, and fuel-less travel throughout the solar system. And perhaps more interestingly, an economically viable way to extract resources from asteroids.

Four years ago, it was the view of international experts in ultrasonic welding that it would be impossible to produce tethers made of extremely thin wires welded together every centimeter. (It’s necessary for the tethers to be created this way, though, so that micrometeoroids, like those that cause meteor showers, don’t cause debilitating damage to the structure.)

But now, researchers at the University of Helsinki have succeeded in creating a 1-km-long ESAIL tether, featuring 90,000 ultrasonic welds. This provides proof that it is possible to manufacture full-size ESAIL tethers. And thanks to this breakthrough, “the theoretically predicted electric sail force will be measured in space during 2013,” the University of Helsinki notes in a news release. The Estonian ESTCube-1 satellite launching in March will first test out a 15-meter-long tether. Followed by a test of a 100-meter tether in 2014.

The development of such a technology would allow for extremely cheap, large-scale gathering of the abundant resources available in space, primarily those available in asteroids and comets.


In fact, all of the “gold, cobalt, iron, manganese, molybdenum, nickel, osmium, palladium, platinum, rhenium, rhodium, ruthenium, and tungsten” that we mine from the Earth’s crust was deposited by asteroid impacts well after the crust on the planet cooled. It’s been estimated that these and many more elements that are used by modern civilization in large quantities may run out within 50-60 years.

The ESAIL also would allow the large-scale mining of water, oxygen, hydrogen, and construction metals; to be used in space. This would completely bypass the currently extremely expensive process of sending objects into space — simply build it there first if it’s possible to do so.

Image Credits: Timo Rauhala; Henri Seppänen & Sergiy Kiprich; Eros via Wikimedia Commons

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James Ayre

James Ayre's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy.

James Ayre has 4830 posts and counting. See all posts by James Ayre

3 thoughts on “Electric Solar Sail Technology Moving Forward, “Impossible To Create” Electric Sail Tether Produced

  • Those metals we mine didn’t come from asteroid impacts after the earths crust cooled. We get a little nickel and iron directly from meteorite impact sites, but that’s about all. See that external hard drive sitting on your desk? Yeah, that’s it. The one with all the German movies on it. The steel in its case came from iron deposits in Australia that were formed over two billion years ago when photosynthesis started releasing free oxygen into the air and started making the iron dissolved in the oceans rust. Iron that was for the most part already there when the earth’s crust formed. Other metal deposits on earth are generally created by the action of water and geothermal heat and since these are lacking on asteroids they tend to be lousy sources of metals other than iron and nickel as the metals are evenly spread instead of concentrated. Asteroid impacts can make conditions that are suitable for the formation of ore deposits, such as cracks in rocks that helped create gold deposits in South Africa, but they don’t directly provide the metals we mine.

    • The iron that was dissolved in the ocean was largely brought there by asteroid impacts. During the Earth’s formation all of the siderophilic (iron-loving) elements are thought to have been pulled into the core by gravity, leaving the crust devoid of them. The crust was then reinfused with these elements as a result of the enormous asteroid bombardments that the Earth experienced in its early days.


      • I thought you were saying that ore deposits are the direct remains of asteroids. I thought that was the case you seemed to be suggesting that asteroids would be good sources of metals other than iron and nickel when they don’t have ore bodies.

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