Apollo astronauts have been speaking about their views on a mission to Mars at a press conference at Nasa headquarters in Washington, to mark the 40th anniversary of the first Moon landing.

While Apollo 10 astronaut Thomas Stafford responded to a question about what Nasa's priorities should be on Mars, Apollo 11 astronaut Buzz Aldrin said: "We'll bring life to Mars, whether its germs or leftover urine bags."

Eugene Cernan, who took part in the Apollo 10 and 17 space missions, said: "Put the human mind on Mars and then we can answer that question".