Former astronauts who took part in the Apollo missions to the moon have called for renewed efforts to send manned flights to Mars.They were speaking at Nasa headquarters in Washington on the 40th anniversary of the first ever lunar landing. Buzz Aldrin, the man who followed Neil Armstrong down the ladder on the first manned lunar mission, highlighted the significance of the Apollo 11 mission’s achievement. “It was certainly pioneering, opening the door when we touched down on the moon,” he said. “That was what enabled humans to put many many more footprints on the surface of the moon.” Some astronauts made impassioned pleas for more adventurous space exploration. “We want to go to Mars,” said James Lovell, who took part in the Apollo 8 and 13 missions. “It’s the least we can do with the International Space Station, because we spent a lot of money up there for almost nothing. It’s a white elephant.” Nasa’s official aim is to return astronauts to the moon by 2020. But under the Obama administration a review is underway of those plans, as well as those for new equipment. Nasa is due to retire its space shuttles next year and replace them with a new spacecraft and rocket.