Astronauts aboard the International Space Station (ISS) are investigating how microgravity affects blood circulation while preparing for a spacewalk scheduled for August 18, according to NASA. The work brought together medical research, ultrasound scans and spacesuit maintenance during a busy day for the Expedition 75 crew. Ground-based doctors monitored the scans in real time as researchers looked for signs of abnormal blood flow and potential clotting risks. NASA Investigates Blood Flow in MicrogravityThe medical work began with Jessica Meir, who collected blood samples inside the station’s Columbus laboratory module as part of the Venous Flow investigation. More… https://t.co/ojn5gUyEaj pic.twitter.com/EWgD8EjoUK — International Space Station (@Space_Station) August 11, 2026The next stage involved ultrasound imaging.