Research results and prototype development and testing for water extraction from polyhydrated sulphate rock on Mars

Document Type

Conference Proceeding

Publication Date



Department of Mechanical Engineering-Engineering Mechanics


Water exists in various forms on Mars. Polar ice caps, buried glaciers, frozen groundwater and hydrated minerals where the water is bound in the mineral structure all can be found in different places. This water can be extracted using different methods and then cleaned and electrolyzed to create liquid oxygen and hydrogen or combined with atmospheric carbon dioxide to create oxygen and methane for rocket propellant. One promising candidate for water extraction from hydrated minerals is gypsum. Gypsum consists of calcium-sulfate and has 2 molecules of water bound in the mineral crystal structure which in practice means that gypsum is about 20% water by weight. From previous studies it was found that water extraction from gypsum is energetically and mass wise the most economical unless direct water ice can be accessed which due to special regions classification may be challenging at first. As part of a NASA Early Stage Innovation grant, a team of researchers from Michigan Technological University (MTU) and Honeybee Robotics (HBR) has been developing technology to excavate gypsum rock and extract water from it. The method that has been developed and tested is based on disaggregation of the gypsum by using a water jet system inside an enclosure to contain the splashing water and maintain a pressure of at least 3kPa to assure water stays liquid. The resulting small gypsum particles and water mixture, the slurry, is sucked into a gravity separation system where most of the liquid water is syphoned off and recycled back to the water jet while the gypsum particles and the remainder of the liquid water are transferred into the reactor vessel and heated to 210C to extract all the liquid water and crystalline bound water. The water vapor is then condensed and captured to feed back into the water jet reservoir and the excess stored for further processing in the cleaning and electrolyzer unit or the Sabatier reactor, depending on what kind of rocket propellant needs to be produced. This paper will discuss the design, development, subsystem testing and relevant environment testing at MTU and HBR. We will discuss each of the subsystems, sizing of the system, energy efficiency and how many variables will affect the excavation process and their testing results up to Technology Readiness Level 4 (TRL-4) which requires subsystem testing in relevant conditions as well as modeling.

Publisher's Statement

Copyright © 2020 by Paul J. van Susante, Jeffrey Allen, Timothy Eisele, Ezequiel Medici, Michael S. Foetisch, Kris Zacny, Zachary Fitzgerald . Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Publisher’s version of record: https://doi.org/10.2514/6.2020-4238

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