Astronauts are trained to withstand as much as nine times the force of gravity. (Three Gs, by comparison, could make the average guy pass out.) But even the toughest among them fall out of the running when it comes to a launch concept from a small civilian company in Goleta, California. To survive the ride on Launchpoint Technologies´s invention, the payload has to be able to survive a brain-splattering 10,000 Gs.

The design calls for a high-speed accelerator that whips a projectile as heavy as 220 pounds around a circular 1.5-mile-radius vacuum tunnel.

The U.S. military relies heavily on satellites for communications, navigation, surveillance and other essential activities. To protect these satellites, some military strategists say we need to deploy defenses that include space weapons. The problem: It's far more expensive and technologically challenging to defend a satellite than to attack one.