Australia's premier science investigation series. Organ Bioprinting: Researchers are growing artificial body parts and printing human tissue from the cells of their patients. Astronaut John Grunsfeld: Meet Astronaut John Grunsfeld. Sitting Is Deadly: Sitting down for prolonged periods of time can shorten our lifespan and regular exercise might not counteract the damage. Peacock Spider: The extraordinary looking peacock spider. Pokie Probability: Mathematician Simon Pampena crunches the numbers on the pokies to work out your chances of winning. Website: http://www.abc.net.au/catalyst/