Instead, NASA should be concentrating on bigger rockets and new places to explore, the panel members said, as they issued their final 155-page report. The committee, created by the White House in May to look at NASA's troubled exploration, shuttle and space station programs, issued a summary of their findings last month, mostly urging more spending on space.
On Thursday in a news conference, panel Chairman Norman Augustine focused on fresh destinations for NASA, saying that it makes more sense to put astronauts on a nearby asteroid or one of the moons of Mars. He said that could be done sooner than returning to the moon in 15 years as NASA has outlined.
The exploration plans now under fire were pushed by then-President George W. Bush after the 2003 Columbia space shuttle disaster. The moon-Mars plan lacks enough money, thanks to budget diversions, the panel said in a 155-page report. Starting in 2014, NASA needs an extra $3 billion a year if astronauts are going to travel beyond Earth's orbit, the panel said.
The Augustine commission wants NASA to extend the life of the space shuttle program and the International Space Station. Space shuttles are due to retire Oct. 1, 2010, but should keep flying until sometime in 2011 because they won't get all their flights to the space station done by that date. And the space station itself - only now nearing completion - should operate until at least 2020, allowing for more scientific experiments, part of its reason for existence. NASA's timetable calls for plunging it into the ocean in 2015.
However, the overall focus of the panel's report is on where U.S. space exploration should be headed.
The White House will review the panel's analysis "and then ultimately the president will be making the final decision," White House spokesman Nick Shapiro said in an e-mail comment.
The committee outlines eight options. Three of those involve a "flexible path" to explore someplace other than the moon, eventually heading to a Mars landing far in the future. The flexible path suggests no-landing flights around the moon and Mars.
Landing on the moon and then launching back to Earth would require a lot of fuel because of the moon's gravity. Hauling fuel from Earth to the moon and then back costs money.
It would take less fuel to land and return from asteroids or comets that swing by Earth or even the Martian moons, Phobos and Deimos, Augustine said.
Eventually, Augustine said NASA could return to the moon, but as a training stepping stone, not a major destination, as the Bush plan envisioned.
Panel member Ed Crawley, a professor at MIT, said NASA should explore the inner solar system "to interest the American public in new destinations."
He noted that so many new asteroids and comets are being discovered each year that the potential first landing spot "is probably one we don't know about yet."
Augustine said landing astronauts on such a near-Earth object could occur in the early 2020s.
In a news conference to discuss their report, Crawley and Augustine said the current NASA plans were well conceived at the time, in 2005. But when money got diverted and launch dates delayed, NASA's new Ares I rocket began to look like it lost one of its major purposes: ferrying astronauts to the space station.
Crawley said the panel liked the idea of a commercially operated, more basic rocket-taxi to get astronauts into the low-Earth orbit of the space station. If NASA spent about $5 billion to help kick-start the embryonic commercial space business to do the people-carrying, then the space agency could concentrate on heavier rockets that do the real far-off exploring, he said.
Those commercial rockets should be ready in about six years, Crawley said.
NASA is slowly delaying some parts of the old moon program. It's rethinking its future annual $10 million spending on a still-unbuilt lunar lander as it awaits Obama's decision on the Augustine panel recommendations, said NASA spokesman Grey Hautaluoma.
George Washington University space scholar John Logsdon praised the report as "more comprehensive" than NASA's current program.
Syracuse University public policy professor Henry Lambright said he worries about changes that will cause a loss in momentum in NASA's exploration plans. "You've got to make a decision and you've got to stick to it if you are ever going to get to Mars."
Senator Richard Shelby, R-Ala., criticized the idea of using unproven commercial carriers instead of the Ares, which was designed in his state. He said the report was "unsatisfactory and disappointing."
Review of U.S. Human Space Flight Plans Committee: http://www.nasa.gov/offices/hsf/home/index.html