If humans do indeed attempt to colonize Mars, they'll have to bring everything they need with them because the Red Planet simply has no resources to count on.  Luckily, someone is already planning the supply chain.

Elon Musk's SpaceX company says it will send an unmanned "Dragon" spacecraft to Mars in 2018, with a goal of bringing down the cost of interplanetary research with repeated missions designed to give researchers a predictable, reliable schedule to work with:

"Essentially what we're saying is we're establishing a cargo route to Mars.  It's a regular cargo route.  You can count on it," Mr. Musk told the Washington Post.  "It's going happen every 26 months.  Like a train leaving the station.  And if scientists around the world know that they can count on that, and it's going to be inexpensive, relatively speaking compared to anything in the past, then they will plan accordingly and come up with a lot of great experiments."

Its earthbound equivalent would be transoceanic shipping.  With container ships constantly crossing the seas on regular routes at regular intervals, corporate planners and logistics professionals don't have to worry about individual ship schedules - they look at the system as a constantly-moving global conveyor belt, and plan their operations around the idea that goods are constantly in motion between two given sites.

SpaceX still has to perfect the Dragon, and hopes to demonstrate the Falcon Heavy - a powerful rocket needed to reach Mars - later this year.