NASA STTR 2010 Solicitation


PROPOSAL NUMBER: 10-2 T3.01-9872
RESEARCH SUBTOPIC TITLE: Technologies for Space Power and Propulsion
PROPOSAL TITLE: Magnesium Hall Thruster for Solar System Exploration

NAME: Busek Co., Inc. NAME: The Pennsylvania State University
STREET: 11 Tech Circle STREET: PO Box 30
CITY: Natick CITY: State College
STATE/ZIP: MA  01760 - 1023 STATE/ZIP: PA  16804 - 0030
PHONE: (508) 655-5565 PHONE: (814) 865-0305

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
James J Szabo
11 Tech Circle
Natick, MA 01760 - 1023
(508) 655-5565

Estimated Technology Readiness Level (TRL) at beginning and end of contract:
Begin: 4
End: 5

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
The innovation being developed in this program is a Mg Hall Effect Thruster system that would open the door for In-Situ Resource Utilization based solar system exploration. Magnesium is light and easy to ionize. Performance advantages of a Mg thruster include far higher specific impulse and less life limiting erosion. Additional advantages include low propellant cost and low pressure propellant storage. A system efficiency >50% is expected from an optimized, high power Mg HET. More importantly, the Isp for a high efficiency magnesium Hall thruster driven by a 400V power processing unit may exceed 5000s. For a Mars-Earth transfer, the propellant mass savings with respect to a xenon HET system are enormous. Mg can also be combusted in a rocket with CO2 or H2O, enabling a multi-mode propulsion system with propellant sharing and ISRU. In the near term, CO2 and H2O would be collected in-situ on Mars or the Moon. In the far term, Mg itself would be collected from Martian and lunar regolith. In Phase I, an integrated, medium power (1-3kW) Mg HET system was developed and tested. Controlled, steady operation at constant voltage and power was demonstrated. Preliminary measurements indicate Isp >4000 s was achieved at a discharge potential of 400V. The feasibility of delivering fluidized Mg powder to medium or high power thruster was also demonstrated. The objective of Phase II will be to evaluate the performance of an integrated, high power Mg Hall thruster system in a relevant space environment. In the first task, we will improve the medium power thruster system and characterize it in detail. In the second task, the knowledge gained will be used to design and build a high power (8-20kW) Mg HET. In the third task, a fluidized powder feed system supporting the high power thruster will be built and delivered to Busek. In the fourth task, the integrated high power system will be fully characterized. Measurements will include performance and plume properties.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Magnesium Hall thrusters are attractive for NASA Flagship, Frontier, and Discovery class missions because extremely high specific impulse is available at voltages typical of low cost, flight qualified power processors. Isp ~ 5000 s is possible at a discharge potential of 400 V, while Isp ~ 6000 s is possible at 600 V. These thrusters can also be deeply throttled. Examples mission targets include asteroids, comets, and the outer planets. Sample return missions are also enabled. Magnesium thrusters are also well suited for lunar and Martian missions. A high power cluster would support manned missions by transporting fuel and cargo. In-situ propellant utilization is possible at the Moon and Mars. Also possible is a multi-mode Mg based propulsion system featuring a Mg rocket and a Hall thruster will full or partial propellant sharing. This multi-mode system with ISRU would greatly reduce the cost of sample return from Mars.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Light metal Hall thruster technology may enhance many critical DoD and commercial missions such as satellite orbit maintenance, orbit raising and repositioning. Magnesium offers far higher specific impulse than possible with xenon with the possibility of long term, low maintenance, propellant storage. High pressure propellant tanks will not be required and spacecraft interaction issues should be manageable. Mg Hall thrusters could also form one half of a multi-mode propulsion system that also contains a Mg based rocket. This system would provide both high thrust and high Isp. The rocket oxidizer would be CO2 or water. The two systems would share propellant feed system components, tanks, and fuel.

TECHNOLOGY TAXONOMY MAPPING (NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.)
Active Systems
In Situ Manufacturing
Maneuvering/Stationkeeping/Attitude Control Devices
Resource Extraction
Spacecraft Main Engine

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