Mars is an inhospitable place. It's cold and, for the moment at least, seemingly lifeless.
That could be about to change in the future though with both NASA and Mars One both looking to land astronauts on the red planet.
There is just one big difference between the two, and it could mean the difference between life and death. While NASA always plans to bring its astronauts back home, Mars One is a one-way trip.
That means that once those astronauts arrive they'll be permanently living on Mars as they attempt to start a colony.
It's spectacularly dangerous, and as such it can bring up some difficult questions, one of which is cannibalism.
In this bonus clip from the online series, Citizen Mars, we will meet these people, try to understand the motives for their applying and ultimately better understand the kind of person that's willing to give everything up on the off chance that should the money be raised they'll be leaving Earth forever.