NASA'S plans to land astronauts on the moon again by 2020 are about to disappear into a giant black hole, according to a panel of space experts appointed by the US President, Barack Obama.

Less than a month after the 40th anniversary of the first lunar landing by Apollo 11, the group has told White House advisers that the space agency simply does not have enough money to do it again.

Old Glory ... too costly to plant another flag on the moon.

Without a significant boost in funding - unlikely with the federal deficit approaching $US1.3 trillion ($1.56 trillion) NASA will almost certainly have to scrap the next-generation Ares I rocket that has already cost more than $US9 billion to develop.

The longer-term part of the agency's $US81 billion Constellation project - to land humans on Mars by the middle of the century, touted by the former president, George Bush, in his 2004 vision for space exploration - will remain in the realms of science fiction, at least for now.