Asteroid Mining

I have been debating what science thing to post today.  There are so many good offerings: labor pain simulators for men, using PET scans to detect brain damage in football players before they know anything is wrong.  I think that I will go with space-themed:  asteroid mining.

What is it you ask?  Well it's mining... In space!

Why?  Aren't there mines here on Earth?  Well, yes, but there are three reasons why mining asteroids makes sense:

1. No need to launch materials into space.  It costs a lot of money to get materials out of Earth's gravity. These are already "out there".
2. Many asteroids contain metals that are relatively rare on Earth.
3. Many asteroids contain water which would be an indispensable commodity to space explorers.

Two major groups working on plans at the moment are:

1. Planetary Resources
2. Deep Space Industries