The most ambitious interplanetary mission ever launched reaches a climax on Friday when a clam-shaped probe plunges towards Titan in a suicidal quest to unlock the mystery of Saturn's biggest moon. If all goes according to plan, the death dive of the European probe Huygens could push back the frontiers of knowledge about the Solar System. For more than four hours, the scout will relay back to its mothership precious data which could help explain the chemical recipe that enabled life to appear on Earth several billion years ago.