September 22, 2006
"Spaceflight is tough."
That’s what STS-115 astronaut Joe Tanner said at the welcome home today at Ellington Field in Houston after fellow spacewalker, Heide Piper, fainted at the podium. Each crewmember offered their thanks to the various training instructors, flight controllers, and family members present, and Heide was in the midst of adding to the list when her knees went all wobbly and she collapsed. While the NASA team tended to her, Joe said, “Spaceflight is tough.” Then indicating Heide, who was already sitting back up, he assured everyone that she was fine and that, “I had that happen to me yesterday.”
Heide returned to the podium with a big smile and said, “That was embarrassing!” She had already called the mission an adventure and seeing the solar array “tremendous,” and promised to keep her speech short, but her knees gave out on her again before she finished. JSC Director and former astronaut Mike Coats, who had introduced the crew and lauded their many accomplishments, was right there to catch her and gently lower her to the floor. She revived again quickly, but they made her get out of the hot hanger and into the air-conditioned offices behind the podium to recover.
A friend who accompanied me to the welcome ceremony wondered why no one seemed terribly surprised or concerned that an astronaut had fainted. I explained that this is not uncommon.
When a person enters freefall, the heart no longer has to pump blood “uphill” to the brain. Blood rushes to the head, and because blood vessels are designed to prevent backflow, like a bathtub with a small drain fills with a shower on, the blood accumulates in the head. The brain signals the body to get rid of this excess fluid by sweating and urination, and after a day or so, the volume of blood has been reduced. In freefall, the heart does not have to work as hard, and it actually shrinks in size over a 3-week period.
When it is time to return to Earth, astronauts do “fluid loading” in anticipation of the body’s sudden need to replace that lost blood volume. The heart muscles have weakened and take weeks to regain their full pumping power. So in the days following landing, astronauts’ hearts have less blood to work with, and are not as efficient as usual at pumping that blood to the head. When a brain doesn’t get enough oxygen, the person faints. Fainting naturally brings the head down level with the heart. This increases blood flow to the brain, restores the oxygen level, and the person revives. Note that fainting will not work in freefall. If someone passes out in freefall because of suffocation or blood loss, a fellow crewmember would have to hold them by the feet and swing them in a circle to increase the blood flow to the head! (There is a lower-body-negative-pressure garment that test pilots use to push blood from the legs to the head that was tested on Spacelab flights.)
The people who work and live with the astronauts are very familiar with the effects of space and Earth adaptation, so were not unduly concerned when Heide fainted. But to assure the media and the school children who were in attendance, she came back out before the event ended and waved to the crowd with a big smile. Canadian astronaut Steve MacLean, who spoke after Heide had left the podium, said that spaceflight “is a human experience.” He said he will now have lots of stories that he will probably tell over and over to his grandchildren someday. He joked that they would get so tired of hearing about his “ultimate experience” that they would use it as at leverage to get him to play with them, saying, “Grandpa, we will let you tell us your space stories if you come and play with us!”
And I can hear myself in the future as well… “I remember the day when one of the astronauts fainted at the welcome back ceremony…” or maybe not. Hopefully, I’ll have some more interesting tales to tell by then!
Congratulations and thanks to the STS-115 crew and ground teams for sharing their expertise and experience with all of us. What a fantastic flight!
Posted by m_dyson at September 22, 2006 05:25 PM