The next mission to land a man on the moon will take place in 2015 at the earliest, the new chief of the United States’ space program said on Monday, adding the mission could be followed by the construction of a multinational space station there.

But NASA has not yet decided what vehicles will be used to reach the moon, or what will succeed the aging space shuttle fleet, which is due to be retired in 2010.

“I don’t have a specific date, but sometime between 2015, which is the earliest we think we can do it, and 2020, which would be the latest,” said Michael Griffin, the new administrator of NASA, when asked at the Paris Air Show about NASA plans to return to the moon.

The last manned mission to the moon was NASA’s Apollo 17 in 1972.

Griffin, who took over the top job at the U.S.’s National Aeronautics and Space Administration in April, is hoping to fulfil President Bush’s high-profile plan to return humans to the moon and possibly to land on Mars.

“We have enough money to put people back on the moon in that timeframe,” he said. “The model that I have is that we should build a lunar outpost similar to the kinds of multinational outposts we have in Antarctica.”

NASA will make decisions on what craft will be used to reach the moon in the next few months, Griffin said: “I am hoping we will have some fairly firm conclusions by the end of this summer.”

NASA is weighing up competing bids for the so-called Crew Exploration Vehicle (CEV), the successor to the space shuttle, which will be retired in 2010. The new vehicle is expected to be compatible with the International Space Station and to play a role in a manned mission to the moon.

The space shuttle fleet has not flown since 2003, when the Columbia shuttle broke apart in mid-air, killing its crew of seven.

An executive of Boeing Co., which is teaming up with Northrop Grumman Corp. to bid for the multi-billion dollar CEV contract, said on Monday he expected to hear very soon whether its bid would move to the next stage of NASA consideration.

“We’re expecting to get notification from NASA even possibly today on whether we are going to be selected to be in the final two competitors,” said Jim Albaugh, president of Boeing’s integrated defense systems unit, at the air show.

Rival Lockheed Martin Corp. is also bidding on the CEV contract.

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