When Virgin Galactic's SpaceShipTwo rocket plane shattered above California's Mojave Desert on Friday, it led to the first in-flight fatality associated with a commercial space effort. The rocket motor is the prime suspect in the explosion but and another concern has to do with the nitrous oxide that interacts with the fuel to generate the rocket power. The National Transportation Safety Board investigators, who arrived on the scene Saturday morning, will lead the probe and Virgin Galactic's billionaire founder, Richard Branson, is due to arrive on the scene. Click through for more on what we know so far about the explosion and crash, which killed one test pilot and injured another.
