Engineering topics

Donahue, Benjamin

Publications and source records attributed to Donahue, Benjamin.

5 records

NASA NTRS2008

Microwave Extraction of Lunar Water for Rocket Fuel

Nearly 50% of the lunar surface is oxygen, present as oxides in silicate rocks and soil. Methods for reduction of these oxides could liberate the oxygen. Remote sensing has provided evidence of significant quantities of hydrogen possibly indicating hundreds of millions of metric tons, MT, of water at the lunar poles. If the presence of lunar water is verified, water is likely to be the first in situ resource exploited for human exploration and for LOX-H2 rocket fuel. In-Situ lunar resources offer unique advantages for space operations. Each unit of product produced on the lunar surface represents 6 units that need not to be launched into LEO. Previous studies have indicated the economic advantage of LOX for space tugs from LEO to GEO. Use of lunar derived LOX in a reusable lunar lander would greatly reduce the LEO mass required for a given payload to the moon. And Lunar LOX transported to L2 has unique advantages for a Mars mission. Several methods exist for extraction of oxygen from the soil. But, extraction of lunar water has several significant advantages. Microwave heating of lunar permafrost has additional important advantages for water extraction. Microwaves penetrate and heat from within not just at the surface and excavation is not required. Proof of concept experiments using a moon in a bottle concept have demonstrated that microwave processing of cryogenic lunar permafrost simulant in a vacuum rapidly and efficiently extracts water by sublimation. A prototype lunar water extraction rover was built and tested for heating of simulant. Microwave power was very efficiently delivered into a simulated lunar soil. Microwave dielectric properties (complex electric permittivity and magnetic permeability) of lunar regolith simulant, JSC-1A, were measured down to cryogenic temperatures and above room temperature. The microwave penetration has been correlated with the measured dielectric properties. Since the microwave penetration depth is a function of temperature and frequency, an extraction system can be designed for water removal from different depths.

Ethridge, Edwin C.↗

NASA NTRS2004

In-Space Propulsion Options for Mars Sample Return Missions

Contents include the following: Review of analysis goal. Analysis introduction: summary approach and goal assumptions. System analysis: propulsion technologies investigated. Analysis results: mission and performance analysis. Cost analysis. Comparison of propulsion technologies. Conclusion.

Donahue, Benjamin↗

NASA NTRS1994

Self Assembling Mars Transfer Vehicles: The Preferred Concept of the Space Transfer Concepts and Analysis for Explorations Missions Study

Recently, one of the most comprehensive design studies of conceptual manned Mars vehicles, conducted since the Apollo era Mars mission studies of the 1960's, was completed. One of the tasks of the study involved the analysis of nuclear thermal propulsion spacecraft for Manned Mars exploration missions. This paper describes the specific effort aimed at vehicle configuration design. Over the course of the four year study, three configuration baselines were developed, each reflecting trade study cycle results of sequential phases of the study. Favorable attributes incorporated into the final concept, including a capability for on-orbit self-assembly and ease of launch vehicle packability, represent design solutions to configuration deficiencies plaguing nuclear propulsion Mars spacecraft design since the vehicle archetype originated in the 1950's. This paper contains a narrative summary of significant milestones in the effort, describes the evolution to the preferred configuration, and set forth the benefits derived from its utilization.

Donahue, Benjamin↗

NASA NTRS1991

Technology needs for lunar and Mars space transfer systems

The determination of appropriate space transportation technologies and operating modes is discussed with respect to both lunar and Mars missions. Three levels of activity are set forth to examine the sensitivity of transportation preferences including 'minimum,' 'full science,' and 'industrialization and settlement' categories. High-thrust-profile missions for lunar and Mars transportation are considered in terms of their relative advantages, and transportation options are defined in terms of propulsion and braking technologies. Costs and life-cycle cost estimates are prepared for the transportation preferences by using a parametric cost model, and a return-on-investment summary is given. Major technological needs for the programs are listed and include storable propulsion systems; cryogenic engines and fluids management; aerobraking; and nuclear thermal, nuclear electric, electric, and solar electric propulsion technologies.

Woodcock, Gordon R.↗

NASA NTRS1991

Logistics impacts on lunar and Mars lander design

The results of trade studies and evaluations done to determine the impact of accommodation and unloading of cargo on spacecraft design are reviewed. It is concluded that the effectiveness of the surface mission to moon or Mars is best accomplished by providing for undivided cargo delivery and for cargo unloading indirectly to earth surface without the aid of a surface system unloader, for immediate cargo drop during descent abort to orbit, for immediate cargo drop in case of need for an emergency ascent from the surface, and for contiguous placement of cab and surface habitat modules. For exploration architectures that include multiple site visits within as much as several hundred km of each other, use of excursion vehicles capable of short suborbital hops to secondary sites is much less expensive in terms of IMLEO than a strategy of using multiple landers or multiple missions.

Donahue, Benjamin↗