Space elevators could get us to Mars in record time — and Japan is planning one for 2050

• A space elevator could make it much cheaper and faster to get goods to other planets, like Mars.
• The Obayashi Corporation based in Japan announced in 2012 plans to begin building one by next year.
• Not only would it cost $100 billion, there are huge technological and organizational challenges.

Imagine a long tether linking Earth to space that could launch us to orbit at a fraction of the cost and slingshot us to other worlds at record speed.

That's the basic idea behind a space elevator.