The Astronaut’s Manicure

Next time someone wants to set a horror movie in space, they could start with this: In space, no one can hear your fingernails delaminate.

Credit: NASA

As we all know, astronauts need to prepare for many gruesome potential perils in their voyages: radiation poisoning, bone demineralization, space sickness from weightlessness, the risk of sudden decompression if a micrometeorite punctures a space suit or pressurized cabin, accidental loss of essential oxygen, food or water supplies, incineration on re-entry, explosions during launch and, of course, the ever-popular drifting off into the eternal void. But here’s one that I never knew about and yet which is positively routine among astronauts who take spacewalks: they frequently lose their fingernails because of problems with the design of their gloves.

As Victoria Jaggerd tells the tale for National Geographic (emphasis added):

A previous study of astronaut injuries sustained during spacewalks had found that about 47 percent of 352 reported symptoms between 2002 and 2004 were hand related. More than half of these hand injuries were due to fingertips and nails making contact with the hard “thimbles” inside the glove fingertips.

In several cases, sustained pressure on the fingertips during EVAs caused intense pain and led to the astronauts’ nails detaching from their nailbeds, a condition called fingernail delamination.

While this condition doesn’t prevent astronauts from getting their work done, it can become a nuisance if the loose nails gets snagged inside the glove. Also, moisture inside the glove can lead to secondary bacterial or yeast infections in the exposed nailbeds, the study authors say.

If the nail falls off completely, it will eventually grow back, although it might be deformed.

The problem was apparently common enough and nuisance enough for NASA astronauts, according to the story, that some of them started removing their own fingernails in advance of their EVAs. My awe at the Right Stuff has never been more visceral and profound than it is at this instant.

One might think that pressure on the ends of the fingers imposed by the snug, firm glove material was traumatizing the fingernails over the hours of a typical EVA and that this abuse caused the nails to drop off. But, reports Jaggerd, a forthcoming paper in in the October issue of the journal Aviation, Space, and Environmental Medicine indicates that pressure on a different part of the hand may be the real culprit. Too tight a fit around the metacarpal joint where the fingers meet the palm may repeatedly interrupt the blood supply to the fingers, and that may be the true cause of the tissue damage that makes the nails release from their beds. Better customization of the gloves or the inclusion of robotic actuators in their joints to decrease the pressure on the fingers may eventually solve the problem for many astronauts.

But until then, we can keep a strong risk of an occupational hazard that might technically be against the Geneva Convention on the list of Reasons Not to Be an Astronaut. If you want more of them, take a look at Mary Roach’s fun new book Packing for Mars, which describes a host of other problems that space travelers experience while living in weightlessness for days, weeks, months or someday even years. Many of the ones she describes are… excretory in nature. I’m not sure whether those would put the painful loss of fingernails into some more bearable perspective or just heighten the misery.

(Or if you don’t have time to read the book, take an hour and go listen to Steve Mirsky’s interview with Mary Roach—part one and part two—for the Scientific American Science Talk podcast. It’s chock full of floaty feculent detail!)

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8 Responses to The Astronaut’s Manicure

  1. jim scoones says:

    Wot am dis PLoS. ……….plis spik da propin

  2. John Pavlus says:

    Totally gross and fascinating. A researcher told us the same thing at the MIT/Knight boot camp I was at this summer… and added that simply holding a tool on an EVA is like squeezing a baseball as hard as you can for hours at a time (because of the way spacesuit gloves constantly want to spring “out” from a gripping position). Puts the occasional dropped space-tool gaffe into perspective.

    • John Rennie says:

      It really does drive home that nothing people do in space is easy, or at least can be assumed to be easy. And it’s something that does make me wonder sometimes about the hopes for space tourism. Not that any of the people going up on Virgin Galactic will be going EVA or even living in weightlessness long enough to have to deal with most of the difficulties, but what does that say about the implicit limitations on a lot of what space tourists can eventually hope to do? If we don’t build spinning stations with artificial gravity, what can we offer space tourists other than quick up-and-down trips beyond the atmosphere?

  3. Steve Silberman says:

    “Feculent”?!?! Thank goodness there are still some English words that are new to me.

    Wonderful piece, John.

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