More than cargo riding on SpaceX launch

Elon Musk's SpaceX will attempt to launch a resupply mission to the International Space Station on Friday. It follows hard on the heels of the Cygnus resupply mission a fortnight ago, conducted by another commercial company, Orbital ATK Inc.

Nasa retired the Space Shuttle in 2011. Since then, it has been relying on Russian capsules to transport astronauts, and commercial companies to haul freight to the ISS. Yet there is more than just three tonnes of supplies riding in the Dragon capsule atop Friday's Falcon 9 rocket launch.