NASA SBIR 2004 Solicitation


SUBTOPIC TITLE:Energy Conversion for Space Applications
PROPOSAL TITLE:Milliwatt Radioisotope Stirling Convertor

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Sest, Inc.
18000 Jefferson Park, Suite 104
Middleburg Heights ,OH 44130 - 3440
(440) 234 - 9173

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
L. Barry   Penswick
18000 Jefferson Park, Suit 104
Middleburg Heights, OH  44130 -3440
(440) 234 - 9173

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
Studies of potential space missions have highlighted the need for very small electric power supplies for a variety of applications. The light weight radioisotope heat unit (RHU) offers a long-life, reliable energy source for such systems which is independent of the surrounding environmental conditions, but a device is needed to convert radioisotope heat into electrical power. In Phase 1, Sest, Inc. investigated and fully defined a complete energy conversion system utilizing a very small Stirling-based convertor powered by a single RHU. It has conversion efficiencies greater than twice that of proposed thermoelectric convertors. Sest, Inc. proposes to complete the detailed design, fabricate, extensively test, and deliver to NASA a functional prototype of a Milliwatt Radioisotope Stirling Convertor (MRSC) system which will clearly demonstrate the performance characteristics of a low power Stirling-based conversion system. The reference MRSC system is designed to produce a net 100 mW or more of useful electrical power from a single RHU over an operating life of 10 years. The overall size of the prototype MRSC package is approximately 80 mm in diameter by 115 mm in length and has an estimated total mass of 250 g, for a specific power of 0.4 We/kg.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The proposed low power generating system, operating at power outputs in the range of 50 to 500 mW, has a number of potential NASA and US government agency applications. Various NASA missions have investigated the potential of RHU powered devices. Such RPS power supplies have the potential to extend the capability of small science payloads and instruments, and to enable applications such as:
? Long-lived meteorological/seismological stations broadly distributed across planetary surfaces
? Small landers at extreme latitudes or in regions of low solar flux
? Surface and atmosphere-based mobility systems
? Subsurface probes, including impactors and autonomous boring devices
? Deep space micro-spacecraft and sub-satellites
Such units could also find application in future human exploration missions involving use of monitoring stations and autonomous devices, similar to the ALSEP [Apollo Lunar Surface Experiments Package] units deployed on the Moon during the Apollo program.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
A number of applications exist in terrestrial environmental monitoring situations that require the use of multiple widely dispersed, small sensor packages somewhat akin to the NASA requirements for space exploration. In the case of the terrestrial applications the sensor packages in many cases are located remotely from local power supplies and must depend on replaceable batteries, solar arrays (if applicable) or natural gas (Propane) heated thermo electric generators. The proposed MRSC system would be directly applicable to many of these applications and have a number of significant advantages.

The advent of MEMS level combustion devices may also provide a long life, combustion driven heat source that could supply the necessary thermal energy for the low power MRSC system described in the proposed work. These combustors could be based on "conventional" combustion techniques yielding source temperatures well above those provided by the RHU configuration or utilize less conventional techniques such as low temperature catalytic reactions providing source temperatures in line with those of the RHU system. Application for such devices could include environmental monitoring, metering of remote / dangerous facilities (for example gas / oil wells) where non-conventional combustion techniques may be required, and a wide range of self-powered industrial and consumer products.

Form Printed on 08-01-05 13:52