Miami - US President Donald Trump's decision this week to return Americans to the Moon makes sense as a way to develop technology to one day reach Mars, but only if Congress allocates the money, experts say.
Reviving an American programme to explore the Moon is seen as a way to boost jobs and morale at home, while encouraging international collaboration with Europe, Japan, China and India -- all eager to explore the lunar surface.
But the notion of paying for such an ambitious mission, which some have pegged at $100 billion, has proven unusually divise among Democrats and Republicans in recent years in a nation where space exploration has traditionally been supported by both sides of the political aisle.
A return to the Moon is "the right thing to do," said John Logsdon, former head of the Space Policy Institute at George Washington University.
"Our policy has now been brought in consistency with the rest of the world, which sees the Moon as an important destination," he told AFP.
"My concern is whether this policy step will be followed up by a commitment of the resources to accomplish it."
Many Americans recall the Apollo era -- particularly the moment when American astronaut Neil Armstrong became the first man to set foot on the Moon in 1969 -- with great pride.
But the nation has not returned to the Moon since 1972.
Lately, America has slumped in the international space race. Since the retirement of the US space shuttle programme in 2011, it cannot send astronauts to the International Space Station without paying some $80 million for a ride on a Russian Soyuz rocket.
Funding falls short
Rallying cries to return to the Moon are not new.
In 1989, president George H.W. Bush declared the United States would once again reach for the Moon, but the Democratic majority in Congress denied the funding.
Then his son, George W. Bush, also a Republican, proclaimed in 2004 that America would return to the Moon as part of a Nasa programme called Constellation. Funding fell short again.
And soon after Barack Obama took office, he cancelled Constellation and shifted the nation's priorities toward visiting an asteroid, then moving on to Mars.
Obama's decision was based on a White House-convened advisory panel chaired by Norman Augustine, who said Nasa was building the wrong rocket for the wrong destination.
The panel also said an extra $3 billion per year would be needed beginning in 2014 to get Americans to the Moon within 15 years, as planned.
"Obama's administration shunned the Moon because it was Bush's project," said retired astronaut Leroy Chiao, who was part of the advisory panel in 2009 that reviewed Nasa's exploration plans.
"Instead, we got an odd asteroid retrieval mission which was regarded as lukewarm at best," he told AFP.
"It's always about funding. Obama called himself the 'Mars President' but it was empty because he didn't fund the programme. True, he gave small increases to Nasa's budget, but much of the additional spending was mandated by law to go for pork barrel projects."
Monday's Space Policy Directive erased the asteroid mission, refocusing the US goals on the Moon and, eventually, Mars.
The rocket and spaceship that would one day carry people to the Moon are already being built, at an estimated combined cost of $18 billion.
Nasa has proclaimed the rocket, called the Space Launch System or SLS, will be the world's most powerful, designed to hoist humans into deep space riding four at a time aboard the Orion capsule, built by Lockheed Martin.
The first SLS launch is scheduled for late 2019. Orion will make its second test flight, but no one will be on board.
Aerospace companies and those representing the growing private space industry applauded Trump's declaration of renewed Moon plans.
"A lunar mission with today's technology would further our understanding of the moon's history and resources," Lockheed Martin said in a statement.
"And it will build a strong foundation that will not only accelerate the US to Mars and beyond."
According to Chiao, Trump's Moon declaration may be politically motivated but the programme has "much technical merit, too."
The White House has not set forth a budget or timeline.
Nasa said its work toward the new directive will be reflected in Nasa's fiscal year 2019 budget request, which comes out in February.
Logsdon said that budget request will reveal a lot.
The amount should be "something that shows they are serious," he told AFP.
"A few hundred million, a half a billion. It doesn’t have to be some massive increase. As long as it is new money, not taken away from other programmes, dedicated to this objective."