Republican presidential hopeful Newt Gingrich has stirred strong passions by claiming he will establish a permanent moon base by 2020 if elected, but experts say he is living on another planet.

The basic idea is not actually as far-fetched as it sounds. NASA in 2006 announced plans to set up a colony on the south pole of the moon, in around 2020, as a base for further manned exploration of the solar system.

"I do not want to be the country that having gotten to the moon first, turned around, said it doesn't really matter, let the Chinese dominate space, what do we care?" Gingrich said on Thursday as he defended his plans in a key Republican debate.

The problem for Gingrich, a space junkie with ideas dating back decades for zero-gravity honeymoons and lunar greenhouses, is that the 2008 financial crisis came along and turned feasible projects into pipe dreams.

"A lunar base by 2020 is a total fantasy," John Logsdon, professor emeritus at George Washington University's Space Policy Institute, told AFP bluntly.

"We got to the moon in the 1960s by spending over four per cent of the federal budget on Apollo. NASA's now at one-tenth of that level."

During boom-time, president George W. Bush called for a return to the moon, followed by Mars expeditions, and NASA drew up plans called Constellation to meet the lofty goals and replace the shuttle fleet when it retired.

President Barack Obama scrapped Constellation in 2010, saying the proposals were "over budget, behind schedule, and lacking in innovation," and the once-proud shuttle fleet lies mothballed.

American astronauts now have to rely on Russian spacecraft to get to the International Space Station and on Florida's "Space Coast," home to NASA's Kennedy Space Center and Cape Canaveral, there is a mood of despondency.

Against this depressed backdrop, Gingrich has left himself open to the charge that his grandiose vision for human spaceflight is an attempt to pander to vulnerable voters.

"By the end of my second term, we will have the first permanent base on the moon, and it will be American," he said Wednesday at a Florida rally.

Never one to shy away from bold statements, Gingrich compared himself to Abraham Lincoln, John F. Kennedy, and the Wright Brothers, boasting: "I accept the charge that I am an American and Americans are instinctively grandiose."

At a time of austerity when many Americans are struggling to make ends meet, even space enthusiasts poured scorn on his quest.

His main rival in the race for the Republican party nomination, Mitt Romney, shot back on Thursday: "I'm not looking for a colony on the moon. I think the cost of that would be in the hundreds of billions if not trillions. I would rather rebuild housing here in the US."

Gingrich has suggested setting aside 10 percent of NASA's budget for prize incentives aimed at boosting the commercial space sector.

NASA's initial plans envisaged a solar-powered base on the moon's south pole that could serve as a forward base for manned missions to Mars, sending man back to the lunar surface for the first time since 1972.

After the permanent facilities were established, the program aimed to set up six-month moon visits, during which trips to the Red Planet could be planned.

NASA has since scaled back drastically and its goal now is to develop commercial initiatives in the hope that a substitute spacecraft will be ready to fly people to the space station by 2015.

Gingrich's opponents have accused him of pandering, but his is a mixed message for Florida's "Space Coast" dwellers as it also calls for a leaner NASA with private companies doing most of the exploring.

The former House speaker's belief that his dreams can be achieved while reducing NASA's budget is "detached from reality," Logsdon said, describing Gingrich's language as "almost irresponsible."

"He has a whole history of unrealistic ideas with respect to the space program that don't correspond either to technical feasibility or political feasibility," Logsdon, a member of NASA's Advisory Council, told AFP.

A commercial space program would need to spring up almost overnight on the back of a fledgling space tourism industry that is already encountering extreme technical challenges.

"Money, technical reality and lack of public support," Logsdon said, explaining the barriers.

"Commercial people invest money to make a profit. Where is the profit in this? You're not going to raise multiple billions of dollars to do this without a very clear return on that investment."