In September 2006, astronaut Heidemarie Piper made headlines—not for having completed a successful mission to the International Space Station (ISS), but for fainting just after she and her crewmates, including Canadian astronaut Steve Maclean, had just returned from their 12-day mission to space. Though the phenomenon of the “fainting astronaut” is a common experience among those newly returned to Earth, ample press coverage of Piper’s temporary condition brought the matter to a new degree of public attention.
Over the past few years, a Canadian medical experiment has been studying this reaction to better understand the phenomena. The experiment studies how long periods in space affect the human body and offers approaches that will better protect space travellers in the future. The investigation also has everyday medical applications, benefiting elderly people who experience fainting spells or falls, and people who suffer from heart diseases caused by sedentary lifestyles.
Dizziness and blackouts are not uncommon among returning astronauts. About 20% of Space Shuttle crewmembers and 80% of the astronauts who spend extended periods on the International Space Station are affected by light-headedness and fainting upon returning to Earth's gravity.
In the weightlessness of space, the heart doesn't have to work as hard. Without the usual force of gravity, blood tends to accumulate in the head and chest. After a few days the body begins to adapt. The astronauts exercise regularly on the ISS so their muscular, skeletal, cardiovascular and other systems stay as fit as possible.
But after the astronauts return to Earth, this adaptation of the cardiovascular system causes blood to collect in their lower body, and so less blood flows to the brain. In some cases, astronauts experience dizziness, while others may faint because not enough oxygen-rich blood reaches the brain.
Researchers believe that this may have health implications for astronauts readapting to gravity after longer flights on the orbiting International Space Station, to the Moon, or even on multiple year missions to Mars.
This experiment is led by University of Waterloo researcher Richard Hughson and sponsored by the Canadian Space Agency. The CCISS experiment (for "Cardiovascular and Cerebrovascular Control on Return from the International Space Station") is the first to try to look fully at how astronauts' bodies cope with microgravity over many months on the International Space Station.
Hughson and his team believe that these experiments can go beyond helping future space travellers who embark on long space missions. The unique archive and some of what is learned about how astronauts maintain their health in space may have down-to-Earth benefits that could help the elderly and people with cardiovascular health problems.
Since 2007, astronauts from a number of missions have participated in experiments in space to further the CCISS study. During Expedition 20/21, Canadian astronaut Dr. Robert (Bob) Thirsk and his crewmates continued to collect data for CCISS while they lived and worked on the ISS. By donning various devices and monitors as they went through various activities, they were able to give researchers information about their blood pressure, heart rate, and other important information about their cardiovascular systems while in microgravity. This data will later be compared with data obtained before launch and after landing.