Apollo 11 moonwalker Buzz Aldrin says the world is at a crucial moment where decisive action from a global leader now would start humans on a path towards the colonisation of other planets:
"I happen to feel that at this juncture in time that a leader of the world of some nation has the opportunity to initiate a clear pathway that can result in creatures from the Earth beginning to settle on another planet in this solar system," he told the BBC's Newsnight programme.
And, perhaps surprisingly for a man who secured his place in the history of space exploration as a member of the crew which made the first lunar landing, he says that such action would be "far more a big deal than Kennedy saying we are going to compete with the Russians to go to the Moon".
Building one crew rocket, which has difficulties, and one big rocket, which won't be ready until 2018, there is no way to get to the Moon by 2020
It is 40 years this month since Aldrin joined Neil Armstrong on the Moon in the celebrated Apollo 11 mission - a mission which combined one of the most daring feats of exploration in human history with one of its most astonishing scientific achievements.
The world was left in awe of the technological prowess and ambition of Nasa and of its people - most particularly of Aldrin, Armstrong and Michael Collins - the men who actually rode atop the Saturn V rocket to the Moon.
The Apollo 11 landing was the culmination of a journey which began with US President John F Kennedy's 1961 announcement of the dramatic and ambitious goal of sending a US astronaut safely to the Moon before the end of the decade.
Return to the Moon
In 2004, another White House incumbent, President George W Bush outlined his vision for the future of US space travel and said that the US would "return to the Moon by 2020, as the launching point for missions beyond".
The planned Constellation system will not be introduced till 2014
But the Space Shuttle programme which has been Nasa's crew transportation system since 1981, will come to an end next year when the last craft is retired.
And though Nasa is working on a replacement system, Constellation, this will not be introduced until 2014-15.
So for five years after the shuttle's retirement in 2010, US astronauts will be dependent on Russia to fly them into orbit on their space capsule, Soyuz.
Aldrin believes that the Constellation system - made up of the Orion capsule and its Ares launcher - cannot possibly be ready in time to meet Mr Bush's 2020 deadline.
"Building one crew rocket, which has difficulties, and one big rocket, which won't be ready until 2018, there is no way to get to the Moon by 2020."
In fact Aldrin does not believe that the Moon should be Nasa's destination target at all - he has called instead for Nasa to refocus its efforts on Mars.
"It is the only other habitable planet," he told Newsnight. "We have sent many rovers there and we have found conditions there that I feel can be made suitable for human existence much easier than the Moon can."
Aldrin famously became the second man to step foot on the Moon
"It is just further away," he added.
But Aldrin does not think this distance is insurmountable - using a "hop, skip and jump" method which he outlined in an article for Popular Mechanics in 2005, he believes we can travel to Mars by stopping off on its moon Phobos:
"We can go and visit that and occupy it for a year, year-and-a-half, and visit it three times before we go to the surface," he said. "It is a logical stopping off point."
Under Aldrin's plan Nasa should scrap the Ares capsule and have the Orion fly on a Delta IV or Atlas V to Mars.
Effects of recession
Key to such an epic voyage is, according to Aldrin, the US turning its back on its go-it-alone space exploration policy and instead galvanising support from other nations which have not been major contributors to the International Space Station (ISS), but which do have space programmes, such as China and India:
"The US needs to begin to chart a pathway and then we are going to find we need refuelling coming from other space craft, and for things to be sent ahead to the surface of Mars to help support the people, we need supplies to be sent there...
The US Space Shuttle programme is due to end in 2010
"We need unity of purpose and unity of leadership."
But is a recession-hit world really ready to contemplate a mission to Mars when the Apollo project, which saw Aldrin travel to the Moon in 1969 was ruinously expensive?
The latest occupant in the White House, President Barack Obama, has ordered a public review of Nasa's manned activities.
The White House's chief scientist, John Holdren, said at the time the Augustine Commission was ordered that "it would be only prudent" to review the human spaceflight programme given the scale of its ambition and "the significant investment of both funds and scientific capital".
When campaigning for the presidency, Mr Obama said that he believes that "Nasa needs an inspirational vision for the 21st Century".
"My vision will build on the great goals set forth in recent years, to maintain a robust programme of human space exploration and ensure the fulfilment of Nasa's mission."
Buzz Aldrin told Newsnight that he will be outlining his thoughts to the Augustine Commission when he returns to the US at the weekend - how closely his vision matches that of Mr Obama remains to be seen.
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