Having evolved under the pressure of Earth's gravity, it isn't surprising that our bodies experience adverse physiological affects after long periods in low-Earth orbit. NASA hopes that a new experiment, the Fluid Shifts investigation, set to launch to the ISS later this year, will shed light on the causes of vision loss and deformation of the structure to the eye often suffered by astronauts over the course of a stay aboard the ISS.
Some 60 percent of the human body is made up of fluids, and they do not behave in the usual way when subjected to the microgravity environment on board the ISS. This unusual fluid shift brings on a condition known as visual impairment and intracranial pressure (VIIP) syndrome, which leads to fluid building up in an astronaut's brain and warping to the structure of the eye. The condition is documented to have affected roughly half of all astronauts to have journeyed beyond the protective shell of Earth's atmosphere.
"Our first aim is to assess the shift in fluids, to see where fluids go and how the shift varies in different individuals," says principal investigator Michael B. Stenger of the Wyle Science Technology and Engineering Group. "Our second goal is to correlate fluid movement with changes in vision, the structure of the eye, and other elements of VIIP syndrome."
The subjects for the experiment will be astronaut Scott Kelly and cosmonaut Mikhail Kornienko. The pair will undertake an extended 12-month tour aboard mankind's furthermost outpost, which is twice as long as the standard expedition duration.
The Fluid Shifts investigation will also make use of the Russian-made Chibis pressure suit that is already aboard the station, and is currently used to prepare Russian cosmonauts for atmospheric re-entry. Chibis has the ability to apply negative pressure on the lower half of an astronaut's body and it is hoped that the technique may prevent fluid from accumulating in an astronaut's brain.
NASA's drive to combat fluid shift in ISS crew members is only the latest of a long line of research aimed at maintaining an astronaut's health over the course of a prolonged stretch in space. The research will of course prove beneficial to astronauts, but will also most likely benefit individuals back on Earth who suffer from conditions that result in swelling to the brain or those forced to endure prolonged periods of bed rest.