In-situ resource utilization (ISRU) equipment would be incorporated into remotely controlled exploratory robots, according to a proposal, to generate fuels and oxidizers to extend operational ranges and to provide occasional bursts of power for actions like drilling into the ground, hopping over obstacles, flying, or transmitting data on high-power radio signals. In its original form, the proposal is directed toward the development of a locally refueled planetary explorer (LORPEX) — an exploratory robot that could function on a remote planet, without need for fuel transported from Earth and without need for heavy, bulky power-generating equipment that would be utilized to full capacity only occasionally. The proposal might also be applicable to remotely located scientific instruments (e.g., meteorological instruments) on Earth, or even to automobiles.

Solar Energy Collected by Photovoltaic Cells would be converted to chemical energy — typically by electrolysis of an oxide to produce a fuel and oxygen.

The basic idea is that instead of using heavy source that would consume transported fuel to generate high power, one would use a lightweight ISRU unit that would slowly generate a fuel and oxidizer from natural material in its vicinity. The fuel and oxidizer would be stored in lightweight containers (e.g. balloons). The stored fuel could then be consumed rapidly in a lightweight engine or fuel cell to satisfy the occasional demand for high power.

Typically, a LORPEX and its ISRU unit would be powered by solar photovoltaic cells (see figure). The ISRU unit would generate a fuel and oxidizer through electrolysis. On Earth, Venus, or Mars, for example, one could use a solid-oxide electrolyzer with platinum electrodes to split atmospheric carbon dioxide into carbon monoxide (the fuel in this case) and oxygen. Alternative ISRU units might include SABATIER reactors that would produce hydrocarbon fuels from locally available natural materials; such units might prove useful for enhancing the performances of automobiles.

Two proposals that depart somewhat from the basic ISRU/LORPEX concept offer important potential benefits in terrestrial applications. One of these proposals calls for the use of ISRU units to partly detoxify automotive exhaust by converting CO and CO2 to O2 and C. The other proposal calls for sending LORPEX-like robots to hazardous waste sites to detoxify dangerous substances.

This work was done by Kumar Ramohalli of Caltech and Massimiliano Marcozzi of the University of Arizona for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at under the Machinery/Automation category, or circle no. 163 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).


This Brief includes a Technical Support Package (TSP).
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Making fuels onboard for power bursts in exploratory robots

(reference NPO20269) is currently available for download from the TSP library.

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