Astronauts' Fingernails Fall Off in Space

While conducting an Extravehicular Activity (EVA), or spacewalk, an astronaut's hands are encased in a marvel of engineering: the spacesuit glove. It's a multi-layered, personal spacecraft for the hands, designed to protect them from the vacuum and extreme temperatures of space. However, when the suit is pressurized, these gloves become incredibly rigid and cumbersome. This stiffness creates constant pressure points, particularly at the fingertips, which get jammed against the hard inner shell of the glove as the astronaut (Review) works. This compression severely restricts blood flow to the extremities, a condition similar to what can happen under a tourniquet.

This sustained lack of circulation can cause trauma to the nail bed, leading to a condition known as fingernail delamination. The damage isn't always immediate or obvious, but in the days and weeks following a spacewalk, the affected fingernail can begin to lift and eventually detach completely. To mitigate this painful and distracting issue, astronauts undergo meticulous glove fittings and keep their nails trimmed as short as possible. The challenge of fingernail loss highlights a persistent difficulty in space exploration: designing equipment that can protect the human body from a lethal environment without causing harm to it in the process.