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

By: Ronald Brak

Ronald Brak — Sat, 12 Jan 2013 03:56:00 +0000

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.

By: Nathan

Nathan — Sat, 12 Jan 2013 03:04:00 +0000

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.

http://www.sciencedaily.com/releases/2009/10/091018141608.htm

By: Ronald Brak

Ronald Brak — Sat, 12 Jan 2013 01:16:00 +0000

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.