Is there a planet beyond Pluto?

In this edition of Naked Astronomy, why scientists are making mud in the laboratory to try free a trapped Mars rover, the discs that give birth to new planets, the space equivalent of an ordnance survey map for the stars and how scientists are seeking the origins of life in outer space. Plus, your queries about the cosmos: could Earth capture a new moon, why is the asteroid belt not just a planet and is there a planet beyond Pluto...