Atmospheric Chemistry Program Seminar

Deliquescence and Efflorescence of Chlorate Salts under Mars-relevant Conditions by Marium Fernanders,
3rd year ANYL student, Tolbert lab
"When searching for life elsewhere in the universe, scientists have mainly focused on finding liquid water. However, in addition to liquid water, the presence of certain types of salts could also be a marker for water and perhaps life. The presence of chlorate salts, on the surface or in the sub-surface, could be an indicator of where to find life and water on present day Mars. Recent research has found that certain types of terrestrial bacteria can survive in per/chlorate-rich salt environments by using these salts as an energy source. Because of the salts’ low eutectic temperatures and ability to deliquesce (liquefy), these salts may be able to provide the ideal conditions (liquid water and energy) where life may be found in either the surface or sub-surface.
In the search for life on other planetary bodies, one of the places where scientists are looking is our closest neighbor: Mars. Mars, like Earth, exists in the “Goldilocks” zone a set area around a star where planetary bodies are not too hot or too cold for liquid water to occur. However, liquid water has not yet been detected on present day Mars. Mars with a little help from salts, could support liquid water on the surface or in the sub-surface through the process of deliquescence, where a crystal salt absorbs water vapor from the atmosphere, like a sponge, and when the conditions are just right turn into a briny droplet of water. This research proposal will study the low temperature deliquescence and efflorescence (when a briny droplet loses water through evaporation and turns back into a salt crystal) of chlorate salts and chlorate salt mixtures under Mars-relevant pressures and temperatures. By doing this, I will improve our knowledge of how chlorate salts behave under conditions where liquid water may be formed on Mars. In order to determine the conditions under which chlorates will deliquesce and eventually effloresce I will use a Raman microscope attached to an environmental cell where the pressure, temperature, and humidity can be controlled to mimic Mars-like conditions. The Raman microscope will allow me to see a salt particle turn into a liquid and back into a crystal using visual and spectroscopic identification. The Raman uses a green laser to probe a specific salt crystal or briny droplet. The light from the laser gets scattered back into a detector and I can then use the light scattering to characterize and identify the physical state, and chemical composition of crystal or droplet. The information will allow me to determine the deliquescence relative humidity (DRH), and the efflorescence relative humidity (ERH) of the chlorate salts and salt mixtures. By determining these fundamental properties as a function of temperature and pressure, we can then use NASA’s Mars rover and satellite data to determine if there are conditions on Mars where aqueous salt solutions can exist, and possibly flow, on the surface or sub-surface."