NASA SBIR 2004 Solicitation


PROPOSAL NUMBER: 04 S3.01-7863
SUBTOPIC TITLE: Precision Constellations for Interferometry
PROPOSAL TITLE: Radio Frequency Micro Ion Thruster for Precision Propulsion

SMALL BUSINESS CONCERN (Name, E-mail, Mail Address, City/State/Zip, Phone)
Busek Co. Inc.
11 Tech Circle
Natick, MA 01760-2213

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Kurt Hohman
11 Tech Circle
Natick, MA 01760-1023

Busek proposes to develop radio frequency discharge, gridded micro-ion thruster that produces sub-mN thrust precisely adjustable over a wide dynamic thrust range. Such propulsion is needed to augment and overlap the present micro Newton propulsion such as colloid thruster. The RF was selected to eliminate the internal cathode of the DC discharge ion thrusters. This cathode could be a life limiting component and consumes propellant. Two types of neutralizers are candidates for the proposed thruster and include Busek's carbon nanotube field emission cathode similar to that developed for the ST7 DRS mission and already demonstrated RF discharge cathode which consumes much less flow than comparable hollow cathode. The performance of the proposed RF micro-ion thruster is expected to approach that of the NASA JPL MiXI which represents the state of the art in small ion thrusters with DC discharge.

In Phase 1 the RF micro-ion thruster will be build and tested and second generation laboratory device will be designed. MIT, our subcontractor, will initiate the development the RF thruster numerical model to support the experimental effort.

In Phase 2 the thruster system will be constructed and demonstrated including the optimized thruster, neutralizer, key parts of the PPU and the feed system.

Missions such as LISA, TPF, MAXIM, and follow on to the GRACE mission require extremely precise propulsion. Colloid thrusters have demonstrated that sub-micro Newton precision and thrust noise can be achieved. The ST7 DRS mission will document that this thrust precision yields s/c position accuracy within few nanometers. Propulsion with higher but overlapping thrust but relaxed precision is required for the coarse constellation adjustments and for reorientation of the constellation to observe other locations in the universe. Because of cryogenic sensors, the propulsion effluent should not thermally radiate or condense on cryogenic surfaces. These considerations lead to the proposed thruster.

Precision propulsion is required by DoD constellation missions such as the Space Based Radar. Commercial earth observation missions could achieve greater accuracy and resolution by using the proposed propulsion capable to maintain extremely precise and jitter free pointing.