Sweat for Science

German astronaut, Alexander Gerst, at a training session at the European Astronaut Centre in Germany in spring 2018, will test special cooling shirts on Earth and in space and is all set to sweat for the project SpaceTex2. On June 6, Gerst arrived at the International Space Station as part of the European Space Agency's Horizons and will help conduct the first experiments to explore how the human body, clothing, and climate interact, about comfort, under zero-gravity conditions. In the study, the examination of the three shirts would take place. Each shirt with a different cooling performance was developed following the SpaceTex experiments on the space station in 2014.

For Jan Beringer, a functional-textiles expert at Germany's Hohenstein Institute, which is managing the project, the examination of three shirts in space makes them highly excited about the results. To examine the shirts, Gerst will have to perform six training sessions on the ergometer (space bicycle) or the treadmill while wearing the functional shirts. These sessions will happen outside of the 2 hours of exercise; space station astronauts undergo daily to prevent bone and muscle loss. The information regarding Gerst's respiratory flow, heart frequency, and oxygen saturation back to Earth via a data downlink will be piped using wearable sensors provided by the Institute of Aerospace Engineering at TU Dresden.

Beringer finds the task not very easy as Gerst has to sweat quite a lot in space to activate the cooling performance of the functional shirts. In normal gravity, warm air descends and draws cold air from the bottom(convection) while in zero gravity body heat form a warm aura and sweat does not drip down, it stays where it occurs which means there is no loss of heat due to convection when in space. 

Also, during any physical activity, heat thus builds up quicker than on Earth, and this results in core body temperature to rapidly climb up the values that are too high to be healthy. In microgravity, sweat and heat transport away from the body very differently than on Earth. Sweating in space doesn't work quite the same way it does on Earth and therefore the shirts there are necessary as conduits for heat exchange. Although an active human body will still attempt to cool itself through perspiration, sweat doesn't evaporate in the absence of gravity, and heat itself doesn't rise off the body. So, to find the right material to wick away sweat and to keep the body cool becomes vital for proper functioning in microgravity. 

 According to the Hohenstein Institute, which is collaborating with the medical department of Charité University in Berlin, the German Aerospace Centre and ESA are on the research where such findings will help scientists create optimized garments for intravehicular activity which would be the clothing worn inside the space station. The institute also noted that the study could also provide valuable insight into the development of functional textiles for extreme climate and physiological conditions here on Earth, such as those potentially brought about by global warming.