How Extravehicular Activity in Space Affects NASA Astronauts’ Body?

Astronauts sometimes need to do spacewalks to accomplish part of their missions. However, extravehicular activity (EVA) can harm the body, and one of the grotesque results affects the finger.

Effects of Extravehicular Activity on the Human Body

Many probably want to go to space as the experience is not available to just anyone who wishes for it. However, going to space also comes with a lot of health risks.

Loss of muscle and bone density occurs. An excess of fluid in the brain causes issues with vision, and in the absence of gravity, bodily fluids are free to float inside the body mindlessly. Additionally, there's the issue of urination and the ability to detect when one needs to urinate, as it mostly depends on gravity. Erectile dysfunction is also a possibility.

A startling proportion of astronauts' fingernails fall out after doing an extravehicular exercise (EVA), also called a spacewalk. This is a particularly hideous drawback to spaceflight.

The condition is known as onycholysis - the separation of a nail (nail plate) from the skin that it sits on in your fingers or toes (nail bed). Usually, it just affects one nail. It appears that air pressure has far more of an impact on the issue than gravity.

The ambient pressure is shallow in space, which harms 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.

"Injuries to the hands are common among astronauts who train for extravehicular activity (EVA)," wrote a team led by epidemiologist Jacqueline Charvat of Wyle Laboratories in a 2015 conference paper.

"When the gloves are pressurized, they restrict movement and create pressure points during tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally more severe injuries such as onycholysis. Glove injuries, both anecdotal and recorded, have been reported during EVA training and flight persistently through NASA's history regardless of mission or glove model."

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How Astronauts' Space Suit Affects Human Body's Reaction to EVAs

Extravehicular activities leave astronauts in a spacesuit for hours. The longest ever recorded was eight hours and 56 minutes, and wearing gloves could reportedly worsen hand injuries.

Researchers discovered a strong relationship between astronauts' risk of injury 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 pretty 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 layer, known as the 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.

Research appears to point to the possibility that improper glove fit could be a factor, despite gloves being custom-made for each wearer, at least for NASA astronauts. However, with new spacesuits for the Artemis age looming, a solution might finally be in sight.