After a Spacewalk, Your Fingernails Experience a Horrifying Thing
NASA astronaut Stephen Robinson performing an EVA in 2005
It's a fact that space travel does havoc with the human body. Over hundreds of millions of years, we evolved in the Earth's environment; remove that habitat, and things start to go wrong
Loss of muscle and bone density occurs. An excess of fluid in the brain causes issues with vision; in the absence of gravity, bodily fluids are free to float around inside the body mindlessly. There's the issue of urination; it seems that our ability to detect when we need to urinate is mostly dependent on gravity.
Furthermore, a startling proportion of astronauts' fingernails simply fall out after doing an extravehicular exercise (EVA), also referred to as a spacewalk. This is a particularly hideous drawback to spaceflight.Yes. It's repulsive. The issue appears to be significantly more related to atmospheric pressure than gravity, and the technical term for it is onycholysis.
The ambient pressure is really low in space, which is kind of bad for human health. Pressurization of the astronaut's space suit is necessary to ensure maximum safety during extended vertical ascents (EVAs). Everything is going OK so far. However, this becomes problematic when it comes to the hands.
NASA astronaut Anne McClain showing a spacesuit glove in 2019. (NASA)
"Hand injuries are frequent among astronauts preparing for extravehicular activity (EVA)," a team headed by Wyle Laboratories epidemiologist Jacqueline Charvat stated in a conference report from 2015.
"Pressurized gloves provide pressure points and mobility restrictions during jobs, which can lead to pain, abrasions, and in rare cases, more serious injuries including onycholysis. Regardless of the mission or glove model, glove injuries—both anecdotal and documented—have been continuously reported throughout EVA training and flight throughout NASA's history."
Ensconced in a spacesuit, an extended vertical jump experience (EVA) can last for an impressive 8 hours and 56 minutes on record. (Yes, there is a spacesuit remedy for the urination problem, before you ask.) Wearing gloves for so long has the potential to both induce and worsen hand injuries.
The use of your hands is quite essential, particularly when carrying out manual labor outside the space station that cannot be completed in any other way. This problem has been carefully considered. No matter how the glove was made, Charvat and her colleagues observed that it always seemed to happen. Furthermore, identifying the precise origin of the issue has proven to be very challenging.
Apollo astronaut Ronald Evans performing an EVA in 1972. (NASA)
Researchers discovered a strong relationship between astronauts' injury risk and the width and diameter of their metacarpophalangeal joints, or the knuckles where their fingers and palm meet, after examining 232 hand injuries that astronauts had to disclose.
According to their research, spacesuit gloves restrict the mobility of these knuckles, increasing the pressure on the fingers and causing onycholysis, tissue damage, and decreased blood flow.
Gloves for spacesuits are actually quite complicated. They are made up of at least four layers: the skin-contact comfort layer; a pressure bladder layer that expands and becomes rigid when the glove is compressed; a restraint layer that counteracts the pressure bladder's stiffness to permit movement; and the outer Thermal Micrometeoroid Garment layer, which is the spacesuit's outer skin and which shields the wearer from, well, space. On its own, this outer layer is composed of many layers.
Cosmonaut Oleg Kotov performing an EVA in 2013. (NASA)
A team lead by engineer Christopher Reid, who is currently employed at Boeing after formerly working at Lockheed Martin, investigated onycholysis injuries in astronauts in an effort to identify risk factors for the condition. Published earlier this year, their study looked at 31 onycholysis injuries reported by 22 astronauts, 27 of which occurred during training exercises and four of which occurred during EVAs.
They discovered that the glove's design did have a big impact. One of the two glove styles used in the study had an 8.5-fold increased risk of fingernail loss. The middle finger sustained the majority of the injuries; glove size and middle finger length were also factors. Women appeared to be more susceptible to onycholysis injuries than men.
Overall, the results seem to point to the possibility that improper glove fit is a factor. But gloves are custom-fit to each wearer, at least for NASA astronauts. However, with the arrival of new spacesuits from the Artemis era, a solution might finally be in sight.
That means you don't have to worry about that one item. Someone now needs to come up with a plan for when you need to burp. Astronauts have to be really committed to their work.
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