Propelling Interplanetary Spacecraft Utilizing Water-Steam

Abstract

Water has been identified as a critical resource both to sustain human-life but also for use in propulsion, attitude-control, power, thermal and radiation pro-tection systems. Water may be obtained off-world through In-Situ Resource Utilization (ISRU) in the course of human or robotic space exploration that replace materials that would otherwise be shipped from Earth. Water has been highlighted by many in the space community as a credible solution for affordable/sustainable exploration. Water can be extracted from the Moon, C-class Near Earth Objects (NEOs), surface of Mars and Martian Moons Pho-bos and Deimos and from the surface of icy, rugged terrains of Ocean Worlds. However, use of water for propulsion faces some important techno-logical barriers. A technique to use water as a propellant is to electrolyze it into hydrogen and oxygen that is then pulse-detonated. High-efficiency elec-trolysis requires use of platinum-catalyst based fuel cells. Even trace ele-ments of sulfur and carbon monoxide found on planetary bodies can poison these cells making them unusable. In this work, we develop steam-based propulsion that avoids the technological barriers of electrolyzing impure water as propellant. Using a solar concentrator, heat is used to extract the water which is then condensed as a liquid and stored. Steam is then formed using the solar thermal reflectors to concentrate the light into a nanoparticle-water mix. This solar thermal heating (STH) process converts 80 to 99% of the in-coming light into heat.