If humans are to live on Mars they will need a stable supply of food. Earth plants are not suited to the Mars climate but we can engineer plants that are.
The race may be on to send humans to live on Mars, but is it worth the effort -- and the spend -- when we have our own problems to deal with on Earth.
The true radiation risk from commercial flying has nothing to do with security scans. A radiation expert explains how much cancer risk the most frequent of flyers take on when they take to the skies.
If we do find life on Mars, it will be difficult to prove that we didn't bring it there from Earth. An insider talks us through what's at stake.