The painkiller that hides the alarm. An aspirin before a spacewalk sounds harmless. NASA’s Office of the Chief Health and Medical Officer (OCHMO) wants it governed anyway. Its working group calls for clear rules on aspirin, taken to prevent decompression sickness and ease pain, and on painkillers around a spacewalk, because acetaminophen, ibuprofen, naproxen and celecoxib can mask the symptoms of decompression sickness: nitrogen bubbles forming in blood and tissue when pressure drops. Silence the pain, and the warning goes quiet with it.

The Moon raises the stakes. This matters for Artemis spacewalks on the lunar surface, in suits at about 30 kPa versus 101 kPa on Earth. Astronauts first breathe pure oxygen to flush nitrogen out of their blood, and the group reviewed prebreathe tests that include walking in partial gravity. A lunar habitat held near 56 kPa would shrink that pressure gap, and the oxygen wait along with it.

A Hole in the Heart, and a Shrug

Good news from the heart. Pills are not the group’s only worry. It also asked whether a patent foramen ovale, an opening between the heart’s two upper chambers present from birth in some people, raises the risk of clots in flight. The answer is « not considered a major risk factor for VTE formation, » says NASA’s OCHMO working group (VTE is a clot that forms in a vein). A small one poses no significant risk, and the group recommends no change to astronaut selection criteria over clot risk. Large ones split opinions: no universal screening, but crews assessed with one should be informed and offered closure.

Bubbles, the unreliable narrator. Heart or no heart, one question remains: can bubbles, counted on an ultrasound scan, warn of trouble? The group found no definitive link between bubble grades and decompression sickness in these walking protocols, and their predictive value remains uncertain on the lunar surface. The gauge meant to guide lunar spacewalk rules has not yet proven it can predict the danger.

[Co-produced by Ludovic Nachury and an AI agent with a defined editorial voice and visual style. Illustrations are AI-generated. Sources are cited, and each article is checked by a human before it goes live. How this works.]