Our Poisonous Moon: Better from a Distance

The moon stabilizes Earth’s axis and regulates the tides, but enjoy it from a distance.  Now there are more reasons you wouldn’t want to live there.

“Long-term human exposure to the lunar environment has never been studied in depth, and it’s quite possible that — in addition to the many inherent dangers of living and working in space – the Moon itself may be toxic to humans,”  wrote Jason Major wrote at Universe Today (emphasis in original).    He was reporting on  a paper produced by an international team of physiologists, pharmacologists, radiologists and toxicologists from 5 countries, who sought to quantify the dangers to humans of extended lunar exposure.

In the ArXiv paper by Linnarson et al., “Toxicity of Lunar Dust,” (open access), the researchers attempted to fill the “knowledge gaps” about health hazards in lunar dust while recognizing that “ground truth” on actual effects will require in situ measurements.  According to Major’s summary, the risks include inhalation of fine dust, skin damage and eye damage.

Lunar dust is not subject to the erosional processes on Earth, so the particles tend to have sharp edges.  These can be compared to “pollutants encountered on Earth, such as asbestos and volcanic ash,” Major said; “lunar dust particles are small enough to penetrate deep within lung tissues, and may be made even more dangerous by their long-term exposure to proton and UV radiation.”  In addition, the microgravity environment of the moon may loft these particles around the airways.

The dust is dangerous on the outside, too.  Apollo astronauts noticed that the dust clings to everything.  Long-term exposure to the sharp-edged particles, even in the safety of a lunar base, could cause skin abrasions, particularly on the fingers, knuckles, elbows and knees.  And if the dust were to irritate or scratch the cornea of the eye, would there be an opththalmologist in the base to prevent blindness?

These were just a few of the risks of extended lunar habitation.  Some of the fine particles might enter tissue cells, or activate the immune system.  They might release free radicals into tissues and organs.  Even if the dust problems could be overcome, the moon remains unprotected from solar UV radiation, the solar wind, solar flares, micrometeorites and high-energy cosmic rays.

The authors listed 34 remaining “knowledge gaps” about lunar toxicity.  If any of these (many suspected to be high to very high risk) were to prove serious, it might cause a reconsideration of the wisdom of sending humans to the moon for extended stays.  Since some of the risks apply to Mars as well (and since the moon would probably be a training base), these findings could put a damper on hopes for manned missions to Mars.

God’s green Earth is starting to look quite nice, isn’t it?  Maybe you’re fretting the heat, the rain, the wind, or the cold.  After a week on the moon, you would count the days to get back home.  There are hazards on Earth, too, but at least you can breathe the air, get dirty in the garden and shower it off, and usually live out a lifetime without the constant protection of an artificial bubble.

Consider that the moon is almost exactly at the same distance from the sun as Earth.  That’s why all the astrobiological optimism about extrasolar planets within habitable zones is mostly hype.  The moon is in the perfect habitable zone, too!  Many other factors are required to make a body habitable.  Time to watch The Privileged Planet again and count your lucky star.*

*The word lucky used here loosely to include Providence.