On Earth, blood flows down from a person’s brain back toward the heart thanks in part to gravity. Many crew members aboard ISS have reported a variety of neurological symptoms in space including headaches that may be related to microgravity’s effect on cerebral blood circulation. Cerebral blood circulation is one of the major regulators of human brain physiology, However, very little is known about the mechanisms ensuring blood outflow from the brain in microgravity.

In an effort to measure this outflow a team led by Paolo Zamboni and University of Ferrara in Italy developed a strain gauge Pletysmography system to investigate this process. This is a non-invasive technique that measures variations in blood flow from the brain to the heart using a stretch sensor encircling the neck and the upper and lower extremities. The experiment also measures how blood flow changes in response to crewmember schedules in space, who don’t follow the typical circadian rhythm schedule of most humans on Earth.

The experiment was carried out by ESA Astronaut Samantha Cristoforetti on Expedition 42 aboard International Space Station. Danish Aerospace supported the coordination of operations and use of the Pulmonary Function System (PFS) together with the Italian Space Agency control center.

The investigation success could help develop countermeasures that will influence the future of human spaceflight on long –duration missions. It could also help medical community on Earth to treat patients with chronic heart failure and neurological disorders.