Professor Stephen Hawking has called for a new era of space conquest akin to Christopher Columbus' discovery of the new world.
In a speech honouring Nasa's 50th anniversary, the 66-year-old astrophysicist said the situation we face "is like Europe before 1492".
"People might well have argued it was a waste of money to send Columbus on a wild goose chase," he mused.
"Yet the discovery of the new world made profound difference to the old."
More: http://news.bbc.co.uk/2/hi/science/nature/7361037.stm