MSc Thesis - ISSC 2018 JPL Conference Presentation

This project pretends to be a summary of my MSc Thesis on Water-enabled Propulsion Technologies for Interplantary Travel and Surface Exploration and Prospecting. This thesis is the result of my work at the Space and Terrestrial Robotic Exploration Laboratory at the University of Arizona.

The first part of the project was based on developing an innovative modular solar steam propulsion unit for interplanetary missions (smallsats and cubesats). This part was actually presented at the Interplanetary Small Satellites Conference, organized by JPL. The second part of the project was to analyze the posibility of employing a quad-engine configuration of a hopping robot for surface exploration, also enabled by steam. 

Due to the lenght of the project, and some private interests of the lab, I considered better to only post here an abstract of the project, as well as the slides presented at the JPL conference. Do not hesitate to contact me for further reference.


Beyond space exploration, there are plans afoot to identify pathways to enable a space economy, where human live and work in space.  One critical question is what are the resources required to sustain a space economy?  Water has been identified as a critical resource both to sustain human-life but also for use in propulsion, power, thermal and radiation protection systems.  Water may be obtained off-world through In-Situ Resource Utilization (ISRU) defined as "the collection, processing, storing and use of materials encountered in the course of human or robotic space exploration that replace materials that would otherwise be brought from Earth.” Water has been highlighted by many in the space community as a credible solution for affordable/sustainable exploration. Why water? Water can be easily extracted from C-class Near Earth Objects (NEOs), surface of Mars and Martian Moons Phobos and Deimos and from the surface of icy, rugged terrains of Ocean Worlds.  However, use of water for propulsion faces some important technological barriers.  A technique to use water as a propellant is to electrolyze it into hydrogen and oxygen that is then pulse-detonated.  High-efficiency electrolysis requires use of platinum-catalyst based fuel cells.  Even trace elements 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.

First, a solar thermal steam propulsion concept is presented. 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 incoming light into heat. In theory, water can be heated to 1000 K to 3000K with a resulting Isp from 190s to 320s. This propulsion system can offer higher thrust than current electrical propulsion methods and represents a high delta-v solution for small spacecrafts. A further understanding of the concentration system, and the heat transfer process in the nanofluid is presented in this work.

In the second part of the thesis, we explore use of steam to propel surface robots for exploration and resource prospecting using a mother-daughter architecture. Up to now, only wheeled rovers have successfully performed surface exploration missions. However, rugged terrains and the existence of caves and pits represent a limitation for these classic robots. Previous work by the SpaceTREx Laboratory presented SphereX as a solution for this limitation. SphereX is a 3 kg spherical robot capable of hopping, flying and rolling through rugged environments, including caves, lava-tubes and skylights. Its initial design was based on a 3-axes reaction wheel attitude control system, and a main thruster to provide delta-v along the z-axis. In this work, an alternative architecture based on a steam powered, quad-engine configuration is presented. The four thrusters will use water as a propellant, that can be provided and recharged by the lander vehicle. A complete kinematic and dynamic model is developed, and the design and capabilities of the system are analyzed.  Together we identify water as a credible propellant not electrolyzed as hydrogen and oxygen, but instead used as superheated steam to propel robotic vehicles and interplanetary spacecraft.

ISSC 2018 - Presentation


Projects by Jorge Martinez

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