Farewell to Cassini, the epic 20 year mission to Saturn

As Cassini's epic journey to Saturn finally ends tonight, Adam Rutherford celebrates the incredible discoveries of a mission that has changed the way we see our solar system. BBC Science Correspondent Jonathan Amos is at Mission Control in Pasadena as scientists assemble to witness the final few hours of the Saturnian observations beforeCassini completes its death dive into the planet. We also hear from key scientists who've played a role in capturing and interpreting the multitude of data from the last 12 years. With contributions from Michele Dougherty, Professor of space physics at Imperial College Robert Brown, Professor Planetary surface processes Arizona University Carl Murray, Professor of Astronomy, Queen Mary,University of London Ellen Stofan, former chief NASA scientistProducer Adrian Washbourne.