NASA SBIR 2004 Solicitation


PROPOSAL NUMBER: 04 S1.04-8862
SUBTOPIC TITLE: Spacecraft Technology for Micro/Nanosats
PROPOSAL TITLE: Micro Resistojet for Small Satellites

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)
Vlad Hruby
11 Tech Circle
Natick, MA 01760-1023

Micro-resistojets offer the best combination of simplicity, performance, wet system mass and power consumption for small satellites (<100kg, <50Watts) requiring mN level propulsion and low to moderate deltaV(<500m/sec). Classical competing devices such as cold gas thrusters have low performance, while liquid bipropellants have both high losses in the mN thrust range and are more complex. The advanced EP devices such as colloid thrusters are suitable for sub-mN thrust while electrostatic or electromagnetic thrusters are suitable for large deltaV missions where their higher dry mass is offset by higher specific impulse.

Busek therefore proposes to develop a complete micro-resistojet system operating on ammonia or methanol delivering thrust up to 5mN, specific impulse approaching 300sec, impulse bit smaller than 1mNsec and power consumption lower than approximately 10Watts. Ammonia was chosen because it is less toxic than hydrazine while offering similar performance. Methanol is non toxic, greatly simplifying s/c fueling which is especially important for low cost missions.

In Phase 1, breadboard system will be constructed and tested on our Maglev thrust stand that can resolve microNewton forces. In Phase 2 an Engineering Model of the system will be developed.

The micro-resistojet has a clear window of superiority when applied to small sats (<50kg) requiring mN level thrust with mission deltaV<500m/sec. Drag makeup and precisely controlled formation flight of multiple small satellites are examples of missions that require such propulsion. NASA's major missions such as the Laser Interferometer Space Antenna (LISA) and Terrestrial Planet Finder (TPF) could also benefit from the micro-resistojet as the device that performs formation reorientation to point to different location in the sky. ESA is developing warm gas thruster for such applications which will be demonstrated on the Lisa Path Finder /ST7 DRS mission.

Surrey Space Systems LTD is the only commercial satellite provider that is actively selling small sats (<100kg). Their major customers are third world countries where the satellites serve as emergency communications platforms. The proposed micro-resistojet is applicable to these platforms. As we plan to develop a self contained "bolt up" micro-resistojet, it could also be used on any commercial satellites as a de-orbit propulsion. In such non-critical application it could operate at reduced peak temperature on any propellant that may be left on board including Xe, N2, N2O, butane, ammonia, methanol, hydrazine and water.