If we had 75 years warning, would humankind be capable of evacuating the planet? This programme examines how you could flee your home habitat: from building a 25km-long spaceship capable of travelling trillions of kilometres to deciding which unlucky souls get left behind.

If we faced a countdown to destruction, could we find a way to survive? In a series of terrifying scenarios, Nat Geo explores how we could unite to ensure the survival of the human race.