The same thing killed 43 per cent of these astronauts. Scientists have a theory

Theory Briefing

• 43% of a studied astronaut group died from the same cause, a pattern striking enough to prompt a formal scientific theory.
• Researchers suspect spaceflight conditions — such as radiation exposure or cardiovascular changes in microgravity — may be the shared culprit.
• The finding raises questions about whether long-duration missions, like a Mars voyage, carry hidden long-term health costs for crews.
• If the link holds, it could reshape medical screening and mission design for future astronauts.