Hosted by Robin Ince and Dr Helen Czerski this episode of the Science Shambles podcast is an audio recording of our weekly Sunday Science Q and A show that goes out at 3pm GMT on our YouTube channel. On this episode Robin and Helen are joined by Dr Simon Singh and Prof Monica Grady to talk codes, comets and Mars. Watch them on our YouTube channel at youtube.com/cosmicshambles and get bonus content and extended conversations with guests by subscribing at patreon.com/cosmicshambles