February 1, 2006 | David F. Coppedge

Space Travel Too Hazardous for Humans

Astronomy magazine’s March 2006 issue contains a couple of sobering articles for those who like to dream of humans mastering the universe.  Asking “Will moon dust stop NASA?”, Trudy E. Bell described the dangers of space dust: “it sticks to spacesuits, wreaks havoc on equipment, and may be physically harmful,” she wrote, citing the experiences of Apollo astronauts who spent mere hours with the stuff.  Moon dust is as abrasive as sandpaper, annoying, and irritating.  Apollo 17 astronaut Gene Cernan became intimately familiar with it when a broken fender on the rover sent plumes of lunar dust onto him and his partner.  In the lunar module, it smelled like gunpowder, irritated the eyes and took three months to grow out from under his fingernails.  He commented, “There’s got to be a point where the dust just overtakes you, and everything mechanical quits working.”
    Things biological might quit working, too.  Bell describes silicosis, a lung disease that has caused death in miners and dust-bowl victims during the Great Depression.  The razor-sharp silica crystals, if inhaled, cannot be removed, and our immune systems are powerless against them.  Furthermore, Bell warns that Mars dust may be even worse.  The strongly oxidized Martian dust may “burn things like plastics, rubber, or human flesh as viciously as laundry bleach.”  It probably smells terrible, too, because there is no forest to purify the environment (see USDA press release).
    In this double-whammy issue of Astronomy that challenges our cherished science-fiction ideals with heavy doses of reality, Jacqueline Garget asked, like The Shadow, “Who knows what dangers lurk in space?”  Beyond just dust, she warned that “Radiation can damage DNA and even kill – and space is filled with it.”  X-ray flares from the sun, which occur unpredictably even during quiet times of the solar minimum, can send lethal showers of particles toward astronauts.  High-energy galactic cosmic rays, largely shielded by our atmosphere, are also dangerous to humans.
    It’s very difficult to protect astronauts from these hazards, because shields typically produce secondary showers of particles that can wreak even more widespread damage than the initial incoming ray.  Maybe engineers will some day figure out how to produce effective and low-mass shielding, but Garget didn’t end her article much more optimistically than did Trudy Bell.  “Years ago, scientists didn’t fully understand space radiation,” she concluded, “and while they know more now, it’s not enough to send astronauts on a 3-year mission safely.  We must learn the long-term effects of space travel on the human body, and how to protect voyagers, before we can boldly and safely go where no one has gone before.”  Apparently the screenwriters for Star Trek conveniently overlooked these hazards.  See also the 09/14/2000, 05/02/2001, 11/06/2003 and 12/08/2003 entries on space radiation hazards.
Update 02/02/2006: New Scientist published an article about the risk of proton radiation in space.  It says that protons, the most abundant particles in space, cause twice as much DNA damage as expected.

This little entry is provided for your appreciation of all you have down here, under our atmosphere, under our magnetic shield, on this lovely and Privileged Planet.  As you safely watch science fiction on TV, enjoy the fact you are not out there with the characters in the cosmic shooting gallery.

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