Wireless TPS Sensors Chris Johnson Jesse Pentzer Brandy Holmes John Sochacki Lucus Wells

Slide #2 Outline Background Needs/Specs Designs  Design 1  Design 2  Design 3 Trade Study Sensors Budget Schedule Challenges Conclusion Acknowledgments

Slide #3 Background The re-entry environment is extremely difficult to model. NASA Ames desires a wireless sensor system that can be integrated into the Thermal Protection System (TPS) of entry vehicles. Complications with adding extra wiring and the risk involved in adding sensors to the mission. A wireless sensor system would remove wiring complexities, reduce mass, and reduce risk associated with cable cutting. With a greater understanding of the environment encountered during atmospheric re-entry the TPS of future missions could be made safer and more efficient.

Slide #4 Needs/Specifications NeedSpecificationTarget ValueUnit Multi-Nodal Wireless Architecture1)Number of Nodes Architecture can Support10 Multiple Sensors per Node2)Number of Sensors per Node5 Multiple Sensor Types per Node3)Minimum Number of Different Sensors Per Node>= 2 Integration with Rise Balloon4)Maximum Size4 x 5 x 0.5inches 5)Maximum Weight16ounces 6)Sensor Pressure0 to 14psi 7)Minimum Sensor Temperature-60°C X-Jet Testing8)Maximum Sensor Temperature1000°C 9)Wireless Signal Range10meters 10)A to D Resolution10bits 11)Maximum Electronics Temperature125°C

Slide #5 Design One

Slide #6 Design One

Slide #7 Design Two

Slide #8 Design Two

Slide #9 Design Three

Slide #10 Design Three

Slide #11 Design Three

Slide #12 Trade Study Value of Designs (1-3) ItemDesign 1Design 2Design 3Comments Low Cost132all will meet budget Small Size312node size minimized Low Weight312low impact on VAST balloon Low Software Complexity231 Low Hardware Complexity312 Low Power Consumption132 Meets additional Priorities231priorities besides #1's Low Packaging Complexity321protective packaging only High Usability213includes versatility Feasibility321 Summation This total would suggest that the completely wireless option has the most benefits

Slide #13 Sensors Omega Type K Thermocouples with Glass Braid Insulation  Range: -270 to 1372 °C  Uncertainty: Greater of 2.2 °C or 0.75%  Cost: $33 for five thermocouples with one meter leads Honeywell ASDX-DO Series Pressure Sensors  Range: 0 to 30 psi absolute  Uncertainty: 2.0% Full Scale  Temperature Range: -20 to 105 °C  Cost: $33.27 Each Omega Thin Film Resistance Thermal Detectors  Range: -70 to 500 °C  Uncertainty: Dependent on Calibration Equation  Cost: $47.50 for pack of five

Slide #14 Budget Common Cost to all designs: $ Design One 9 PCB’s 9 Batteries 9 X-Bee chips Total Cost: $ Design Two 11 PCB’s 3 Batteries 3 X-Bee’s Total Cost: $ Design Three 11 PCB’s 5 Batteries 5 X-Bee’s Total Cost: $ Thermal Exposure’s Budget: $2240

Slide #15 Schedule

Slide #16 Challenges Code Complexity RF Opaque Materials Design Packaging for Harsh Landing Conditions Thermal Protection of Circuit

Slide #17 Conclusions  Thermal Exposure’s Favorite?  Design One!!!  Why?  Versatility  Simplicity of Code  Simplicity of Design  Small Size and Weight

Slide #18 Acknowledgments Faculty Advisors  David Atkinson  Steve Beyerlein Mentors  Greg Swanson  Tye Reid  Justin Schlee NASA Ames  David Hash  Johnny Fu  Ed Martinez

Slide #19 Questions?