Profiting on Asteroids

Some of the first questions which come up in any practical discussion of space colonization are questions of economics. Suppose we go out and settle on a convenient asteroid with our little spaceship, what do we do when we get there? How do we make a living? What can we expect to export in order to pay for necessary imports? If space colonization makes any sense at all, these questions must have sensible answers. Unfortunately, we cannot hope to answer questions of economics until the asteroi...

 How to Disguise a Helium Atom as a Hydrogen Atom

Donald Fleming of the University of British Columbia in Vancouver, Canada, and colleagues managed to disguise a helium atom as a hydrogen atom byreplacing one of its orbiting electrons with a muon, which is far heavier than an electron. Because it is so heavy, the muon sits 200 times closer to the helium nucleus than the electron it replaces and cancels out one of the nucleus's positive charges. The remaining electron then behaves as if it were orbiting a nucleus with just one positive ch...