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Dusted and dirty helmets and space suits stowed inside Lunar Module after final Apollo 17 moonwalk in December 1972. Credit: NASA |
The alien and perilous dust on the moon has prompted scientists to ponder lunar health standards that would be set before astronauts go there again.
A diverse team that includes flight surgeons, industry air quality experts, toxicologists, lunar geologists, and even an astronaut is examining how harmful lunar dust could be to humans.
?Lunar dust is unlike any kind of dust we?re used to breathing on Earth,? said Noreen Khan-Mayberry, space toxicologist at NASA?s Johnson Space Center in Houston, Texas.
She and other members of the Lunar Airborne Dust Toxicity Advisory Group (LADTAG) have some concerns about the toxicity of the chemically reactive lunar dust grains, which also contain nano-particles of natural metal and glass shards formed from a combination of chemical reactions, meteorite impacts and solar wind bombardment.
LADTAG will help NASA set health standards for astronaut exposure to the dust — a necessary step for designing the spacecraft, rovers, and habitats that will return humans to the moon.
When the first Apollo astronauts stepped onto the moon, one of the lesser problems they were expecting was dust. But they soon found the gray stuff clogging up instruments and causing breathing and vision problems inside the lunar lander.
Alan Bean, Apollo 12 astronaut, noted that trying to brush the dust off only rubbed it deeper into their spacesuits. That clinginess comes from both the barbed shapes of lunar dust grains and an electrostatic charge built up by solar wind exposure, because the moon lacks a protective magnetic field like the one that shields Earth.
Lunar dust consists of uneven rock grains too small for the human eye to see. The constant bombardment from solar radiation has left them porous like ?swiss cheese,? said John James, chief toxicologist for NASA at the Johnson Space Center and co-chair of LADTAG.
The grains range from spherical to highly angular shapes, remaining sharp and unworn by any wind or other natural processes.
?It?s the glassy properties and jagged shape that create abrasiveness,? James said, adding that the ?sandpaper? effect could damage spacecraft hardware and spacesuits.
The LADTAG team wants to examine how such an effect could similarly damage sensitive human skin and eyes, Khan-Mayberry noted.
The moon?s near-vacuum environment also leaves lunar dust grains covered with chemically reactive bonds which would normally become neutralized through interaction with atmospheric gases such as oxygen. That means they might react in highly toxic ways when breathed into the lungs, although scientists hope that the dust will become less threatening in a lunar habitat after reacting with the indoor air.
LADTAG researchers test such exposure in two ways. One method injects fluid mixed with lunar dust into the lungs of an anesthetized lab mouse or rat, while another method puts lab animals in cylinders containing lunar dust to watch them inhale it normally.
The second method better simulates how astronauts might breathe in lunar dust, but it also requires more of the ?finite? lunar dust supply brought back from the moon, Khan-Mayberry said. The LADTAG team may eventually resort to grinding down larger lunar dust samples to add to the supply.
Figuring out the quirks and characteristics of lunar dust has proven a team-building exercise that combines geological studies with medical knowledge.
?What?s really made this interesting is getting lunar geologists and toxicologists to communicate,? said James. ?I think we?re going to come up with some really remarkable stuff from our interaction.?
LADTAG plans to present its findings to NASA around 2010, which will hopefully allow the space agency to set health standards for astronauts who may work around lunar dust. That would also push engineers to design habitats and rovers that could keep dust out, and maybe even put lunar dust to good use.
However, the group?s work won?t end there — members will tackle the next challenge of Mars by reorganizing as MADTAG.
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