ExoMars 2016: "One of the most important things we can do"

A spacecraft will set off for Mars today on a mission to find evidence of life on the planet.

Space expert Professor Tim O'Brien says any mission to Mars is really important, and finding if there's any evidence of life there is one of the most important things we could ever try and do.

Ricky chats to the astrophysicist to find out what this latest mission is all about...