Article Posted on : - Oct 13, 2010

MASSACHUSETTES (BNS): A significant number of astronauts sustain hand injuries during extravehicular activity training and operations.

The most common type of injury reported by astronauts involved in  EVA or spacewalk  include a condition known as fingernail delamination, in which the nail completely detaches from the nail bed, according to a MIT report.

Researchers exploring the cause of fingernail delamination until recently suspected that finger length might play a role because astronauts' fingers push against thimble-like structures inside the tips of the gloves.

However, a recent statistical analysis by researchers and students in the Man Vehicle Laboratory (MVL) of MIT’s Department of Aeronautics and Astronautics has revealed that the width of an astronaut’s hands — not finger length — may be linked to delamination.

Their analysis of more than 200 astronaut injuries indicates a significant correlation between injury and the length of astronauts’ metacarpophalangeal (MCP) joint, located where the fingers meet the palm.

The study suggests that spacesuit glove design inherently limits MCP joint mobility, which, in turn, is related to excess pressure on finger pads that reduces blood flow to the fingers and causes tissue damage that can lead to delamination.

The current study examined a database of 232 crew members’ injury records collected by NASA’s Johnson Space Center.

The gloves are considered the greatest engineering challenge for spacesuit design said Newman, who has spent the past two decades testing the performance of the Extravehicular Mobility Unit (EMU) spacesuit that NASA astronauts have worn since the 1980s.

That’s because our hands have almost as many degrees of freedom as the rest of our entire body, and maintaining those degrees of freedom to enable fine motor control in a pressurized glove is very difficult, she said.

Although the current EMU advanced “Phase VI” gloves were intended to provide better mobility and more comfort than their predecessor, hand injuries are still a significant problem. Of the 350 EVA training injuries reported between 2002 and 2004, nearly half were hand-related, according to a 2005 study.