<p>Forty years ago this January, the Space Shuttle Challenger disintegrated on its way into orbit. All seven astronauts on board were killed.</p><p>In the days after the tragedy, the world wanted answers. What really caused the shuttle to explode? And should the launch have been stopped altogether?</p><p>For season five of Science Friction, Dr Karl Kruszelnicki and Fiona Pepper investigate how the Challenger disaster unfolded – and what that has meant for space exploration from 1986 to now.</p><p>The Challenger Legacy is a five-part series from Science Friction. Episode 1 is out Wednesday 21st January.</p>