Lecturer: Philip Metzger, University of Central Florida
Dr. Philip Metzger is a planetary scientist with the Florida Space Institute at the University of Central Florida performing research related to asteroidal, lunar and Martian regolith and exploration technology. He is Principle Investigator of a NASA project to develop small spacecraft that use planetary ice for thruster propellant. In 2014 he retired from NASA’s Kennedy Space Center where he co-founded the KSC Swamp Works. He was selected as Kennedy Space Center’s Scientist/Engineer of the Year for 2011. He also received the astronaut’s Silver Snoopy award in 2011.
Topic: Water Extraction and Cleanup
Water is considered by many to be the key to the space economy. The cost of launching water from Earth makes it worth more than its weight in gold. Its uses include conversion into rocket propellant, life support, or radiation shielding. It can be extracted from carbonaceous asteroids or from the polar regions of the Moon. In carbonaceous Near Earth Asteroids it exists chemically bound into the minerals including phyllosilicates (as hydroxyl) and hydrated sulfates (as molecular water) rather than merely physically adsorbed onto the minerals. Thus, it requires temperatures as high as 500 deg C to liberate into vapor form. Lunar deposits include hydrogen of unknown form buried beneath an overburden of 30 cm to 1 m in the “shadowy” regions around outside the permanently shadowed regions (PSRs) and ice of unknown physical state that is apparently at the surface (little to no overburden) as well as mixed into the regolith to some depth inside some of the south pole’s PSRs. Presumably these deposits can be liberated by heating but strip mining the ice or the overburden before heating may beneficially isolate the deposit. Thermal extraction tests with carbonaceous asteroid simulant shows that the resulting water is not pure water but contains high quantities of metal ions, dissolved carbon dioxide, possibly organic precipitate, and possibly other constituents. The LCROSS impact on the Moon showed that ice in the PSRs is not pure water but contains carbon and nitrogen compounds plus metals and more. Less is known about the Martian case, but presumably extracted water will be similarly mixed. The Martian regolith is known to contain a high concentration of perchlorate, which is toxic and is a concern in terrestrial water supplies. In each case, the water will need to be cleaned up prior to use. NASA has been developing water cleanup technologies to make the water safe for use at a human-tended outpost. Distillation may recover other usable resources from the water. Cleanup requirements and processes will need to be developed for each of the possible uses of space water.
Recommended Readings:
Prototype Development of an Integrated Mars Atmosphere & Soil Processing System (click here to download)
Microwave Extraction of Water from Lunar Regolith Simulant (click here to download)
Lunar Water Resource Demonstration (click here to download)
Lecture Slides: click here to download
Recorded Talk: click here to view