This week, how analysing tweets can gauge the mood of people around the world, a new way to predict someone's risk of a heart attack, the new field of 'designer plastics' and how Mercury is providing a window into our early Solar system. Plus, the launch of a Chinese Space Station, using glowing bacteria to encode secret messages and the results of this year's Ig Nobel awards including dizzy discus throwers, beetles mating with beer bottles and a drastic way to stop illegal parking...