Does weightlessness cause blood clots?
The uncertainty of science: A new study on Earth using an “dry immersion tank” now suggests that weightlessness could increase the chances that female astronauts could get blood clots during long space missions.
First reported in 2020, an International Space Station mission detected an unexpected blood clot in a female astronaut’s jugular vein. To date, space-health research has had more male participants but with the number of female astronauts on the rise, a new SFU–European Space Agency study examined how microgravity affects blood clotting specifically in women. Key findings
- 18 female participants experienced five days of continuous simulated microgravity in a European Space Agency (ESA)-sponsored VIVALDI I dry immersion study.
- Coagulation time (the time it took for blood clots to start forming) was longer.
- Once started, clots formed faster.
- Once formed, the strength and stability of the clots was greater
The dry immersion tank is “a specially designed water bath with a waterproof sheet to keep participants dry while floating, and simulating weightlessness.”
The researchers admit these results are very uncertain. For one, none of the clots that occurred during the study were “clinically concerning,” which means they were the kind of clots that the body deals with normally without threat. The researchers also noted in their paper’s abstract that “current published research on this topic is male-centered,” which explains the female focus of this particular research.
This research suggests that blood clots could be an issue on long missions in weightlessness, but the data is sparse and very incomplete. Moreover, based on more than a quarter century of missions longer than six months in space, it appears the one blood clot cited above might have been the only incident so far recorded. And any results using immersion tanks on Earth is questionable, as they are a poor substitute for actual weightlessness in space.
Nonetheless, these results add weight to the need for developing interplanetary spaceships with some sort of artificial gravity. Without it, the health of any passengers going on long missions to other planets like Mars is certainly at risk, not simply from blood clots but from bone loss, vision damage, spinal deformities, and overall loss of cardio-vascular and muscular strength, all issues that have been documented well in space.
The uncertainty of science: A new study on Earth using an “dry immersion tank” now suggests that weightlessness could increase the chances that female astronauts could get blood clots during long space missions.
First reported in 2020, an International Space Station mission detected an unexpected blood clot in a female astronaut’s jugular vein. To date, space-health research has had more male participants but with the number of female astronauts on the rise, a new SFU–European Space Agency study examined how microgravity affects blood clotting specifically in women. Key findings
- 18 female participants experienced five days of continuous simulated microgravity in a European Space Agency (ESA)-sponsored VIVALDI I dry immersion study.
- Coagulation time (the time it took for blood clots to start forming) was longer.
- Once started, clots formed faster.
- Once formed, the strength and stability of the clots was greater
The dry immersion tank is “a specially designed water bath with a waterproof sheet to keep participants dry while floating, and simulating weightlessness.”
The researchers admit these results are very uncertain. For one, none of the clots that occurred during the study were “clinically concerning,” which means they were the kind of clots that the body deals with normally without threat. The researchers also noted in their paper’s abstract that “current published research on this topic is male-centered,” which explains the female focus of this particular research.
This research suggests that blood clots could be an issue on long missions in weightlessness, but the data is sparse and very incomplete. Moreover, based on more than a quarter century of missions longer than six months in space, it appears the one blood clot cited above might have been the only incident so far recorded. And any results using immersion tanks on Earth is questionable, as they are a poor substitute for actual weightlessness in space.
Nonetheless, these results add weight to the need for developing interplanetary spaceships with some sort of artificial gravity. Without it, the health of any passengers going on long missions to other planets like Mars is certainly at risk, not simply from blood clots but from bone loss, vision damage, spinal deformities, and overall loss of cardio-vascular and muscular strength, all issues that have been documented well in space.













