SUNNYVALE, California – If the Bush administration's plan to set up a base on the moon is to become a reality, scientists will first have to devise a way to deal with a tiny but ubiquitous enemy: lunar dust.

Lunar dust is extremely abrasive – and unavoidable – as astronauts quickly learned during the Apollo missions of the 1960s and '70s. Within hours, the dust covered the astronauts' spacesuits and equipment, scratching lenses and corroding seals.

Fortunately for the astronauts, their contact with lunar dust was short enough that it didn't cause any major problems. But explorers living on a moon base for weeks or even months at a time are not likely to get away so clean.

Under prolonged exposure, the explorers would be at risk for everything from mechanical failures in spacesuits and airlocks to lung disease, said researchers last week at a NASA workshop focused on the issue.

"Dust is the No. 1 environmental problem on the moon," said Apollo 17 astronaut Harrison Schmitt, who reported having a severe allergic reaction to moon dust during his mission in 1972. "We need to understand what the (biological) effects are, because there's always the possibility that engineering might fail."

Moon dust is much more jagged than dust on Earth because there's no water or wind on the moon to toss it around and grind down its edges. It's created when meteorites, cosmic rays and solar winds slam into the moon, turning its rocks into powdery topsoil.

The Apollo astronauts couldn't help but get covered in the stuff as they struggled to stay upright on the moon's surface, where the force of gravity is one-sixth of that on Earth. Later, they tracked the dust back into their space capsules and inhaled it when they took off their helmets.

"When you go weightless again, it shook up from the floorboards," said Schmitt. "It smelled like spent gunpowder."

Though no astronauts have reported coming down with any illnesses due to their contact with lunar dust – save for Schmitt's brief allergic reaction – samples brought back to Earth have some peculiar properties that worry researchers.

For one, some of the dust particles are only a few microns wide. This makes it easy for the particles to get deep into the lungs and stay there. Scientists worry that this could eventually lead to fatal lung diseases similar to silicosis.

Also, the dust is littered with bonded shards of glass and minerals known as agglutinates, which were formed in the heat of meteorite impacts. Agglutinates have not been found on Earth, and scientists worry that the human body may not be able to expel them efficiently if inhaled.

"They have sharp angles, with arms that stick out and little hooks," said David McKay, chief scientist for astrobiology at NASA's Johnson Space Center. "It's like Velcro."

McKay and other speakers at the workshop offered suggestions for limiting astronauts' exposure to dust – for instance, by setting up showers or electrostatic devices that pull the dust off the astronauts' suits. But they cautioned that solutions like these would be hasty without further research into the biological effects of lunar dust.

American researchers have hardly bothered to study the topic since the United States ended the Apollo program in 1972. And foreign studies on samples from the Soviet Luna program have been widely rejected on the grounds that the studies were flawed.

Getting studies rolling again will not be easy. Laurent Sibille, a research scientist with NASA's Marshall Space Flight Center, estimates that researchers will need 100 tons of space dust for testing in the run-up to a new moon mission.

The Apollo astronauts brought back less than 1 percent of that amount, and the original 25 tons of fake "simulant" dust that NASA created for researchers is now gone, with the exception of one bucketful at Johnson Space Center.

Sibille and other speakers called on NASA and the aerospace industry to begin developing a new simulant as soon as possible.

Understanding how lunar dust affects humans is imperative to any future missions, said Russell Kerschmann, life sciences chief at NASA's Ames Research Center.

"How much of a problem this is, we don't know," said Kerschmann. "And that's a problem."

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