President Barack Obama is due to meet the crew of Apollo 11, exactly 40 years since they landed on the moon. Neil Armstrong, Buzz Aldrin and Michael Collins are attending an event at the White House in Washington to mark the anniversary. On this day in 1969, the trio fulfilled President John F Kennedy's promise to put a man on the moon by the end of the decade. It is expected they will push the current US leader into funding a mission to Mars. In a speech on Sunday, Mr Aldrin said: "The best way to honour the Apollo astronauts is to follow in our footsteps; to boldly go again on a new mission of exploration."