January 7, 2007
Scientists Are Split on Whether Lunar Base is Too Ambitious
By Jeremy Manier
NASA's evolving plans for building a permanent moon base by 2024 portray the facility as a scientific outpost where astronauts will build telescopes, forage for rare minerals and prepare for future Mars missions to be launched from the lunar surface.But the reality is likely to be far more modest, many scientists say, with few tangible scientific benefits in the short term. Some researchers who support the return to the moon argue that the National Aeronautics and Space Administration should downplay any potential scientific payoff and focus instead on the sheer adventure of people exploring and living on new worlds.
The rationale--and cost--of President Bush's proposed moon base will be among the first priorities for the new Democratic leaders of the congressional committees that oversee NASA's budget and goals. The Democrats say the administration must explain how it will pay for the base, expected to cost around $200 billion over 20 years, without raiding other missions such as unmanned probes and studies of the Earth.
What supporters and opponents of a moon base fear most is a repeat of the International Space Station, widely considered one of NASA's worst failures. That facility has not delivered on promised research benefits and brought few inspiring images of exploration from its perch in low Earth orbit.
"This [moon base] is the space station writ large. It's building something just for the purpose of having something for people to do in space," said astrophysicist Steven Weinberg of the University of Texas, a Nobel laureate and frequent critic of the manned space program.
The researchers with the most to gain from a permanent moon outpost are experts in lunar geology, who see a chance to finally glimpse the moon's full history, including details of how it is thought to have formed from a Mars-sized planet's collision with Earth more than 4 billion years ago. But even those enthusiasts say NASA's recent experience offers a cautionary lesson.
"The big thing is, we don't want this to be another space station," said Clive Neal, an expert in lunar geology at the University of Notre Dame and chair of NASA's Lunar Exploration Analysis Group.
Telescope may be problematic
The scientific goals that the space agency cited when unveiling its moon-base plans last month included the possibility of building optical telescopes that would benefit from the moon's lack of a blurring atmosphere. Yet at a NASA-sponsored conference in November on uses of the moon for astronomy, many experts argued that space-based instruments such as the Hubble Space Telescope have advantages over moon-based observatories.
Among other drawbacks, the moon is dusty, has gravity that could distort a large telescope lens and experiences "moonquakes" that could interfere with observations.
"The general feeling was that we're doing so well now in space that there's no real reason to go back to the moon for astronomy," said Paul Lowman, a geologist at NASA's Goddard Space Flight Center.
Yet Lowman, who began work on plans for a moon base during the Apollo program heyday of the 1960s, said the moon may be suited for specific astronomical tasks. The moon's far side, which always faces away from Earth, has less radio noise than anywhere else in the solar system, making it a plausible site for radio telescopes. Lowman also sees potential for arrays of refrigerator-sized telescopes that could be linked to create high-resolution images.
Some boosters of the new moon missions argue that helium-3, an isotope rare on Earth but common on the moon's surface, could be used to fuel nuclear fusion reactors on Earth. But no one knows if reactors based on helium-3 would be technically or economically feasible.
Even if the moon were made of solid gold, it's doubtful that exporting lunar resources to Earth would be profitable. Manned missions using the space shuttle cost about $10,000 per pound of payload--about the price of a pound of gold.
In Bush's 2004 speech outlining his exploration proposal, he described the moon as "a launching point for missions beyond." But most experts say physically launching Mars missions from the moon would require an industrial aerospace infrastructure on the moon that would take decades or even centuries to develop.
"Sometime in [the] next 100 years we may have the construction base on the moon to do this, but in the near term it makes no sense," said Lawrence Krauss, a physicist at Case Western Reserve University who supports building a human presence on the moon over the long term.
Laurie Leshin, director of sciences and exploration at NASA's Goddard center, said the agency is casting a wide net for scientific proposals on how to use a moon base. The early goals Leshin highlighted are modest, including searching for ice deposits at the lunar poles, studying impact craters and taking core samples that could shed light on patterns of solar activity over billions of years.
"Science is one of the great things we can do [on the moon], but it's not the only reason we're going or frankly even the primary motivator," Leshin said.
It is a peculiar fact of the current moon project that the effort to create a scientific rationale comes after Bush's decision that the moon would be NASA's next destination. But some scientists say that's appropriate, because pure research has always piggybacked on the broader political reasons for sending people to explore space.
"No one would argue that [a lunar outpost] is worth the cost if it's just about the science," said Krauss of Case Western.
Astronomer Neil deGrasse Tyson, who serves on NASA's external advisory council, took Krauss' point a step further.
"If you only considered science, there's hardly ever any reason to send people into space," said Tyson, director of the Hayden Planetarium at the American Museum of Natural History in New York.
Still, Krauss and Tyson said, they believe a lunar base is worthwhile. Tyson said the key is to separate the potential for scientific discovery from the human drive to explore.
"As long as there is a continuously moving frontier in space, there will always be science to do," he said. "If you stop moving the frontier, you're done."
Human exploration of the moon will benefit science indirectly, Tyson said, since manned spaceflight is "one of the greatest drivers of the educational pipeline that produces scientists and engineers."
But instead of leaning on a scientific justification, Tyson said backers of a lunar outpost "ought to have the guts to say, 'We want to do this because great nations explore.'"