Wireless Thermal Protection Sensors Presented By: Jesse Pentzer and Lucas Wells Brandy Holmes John Sochacki Chris Johnson

Introduction Motivation Prototype Prototype Specs Software X-Jet Testing Outline X-Jet Results VAST Flight VAST Results Challenges Conclusion

Project Goal: Design and build a wireless system to gather data from sensors embedded in the thermal protection system of re-entry probes. Project began in 2006 with team ThermaSense ThermaSense developed proof of concept Thermal Exposure developed the ThermaSense system further, moving toward flight testing Introduction

Multi-nodal system Multiple sensor types Gather data during NASA Ames X-Jet tests from multiple nodes Integrate with VAST to log data on successful high altitude balloon flight Project Goals

Sensor Node: PIC Microcontroller Wireless ZigBee RF Transceiver (UART) Absolute Pressure Sensor (I 2 C) Cold Junction Correction Chips (SPI) – converts thermocouple voltage to a digital temperature value Data Storage Node: – Rabbit RCM3365 with 128 MB Flash Card Expandable architecture Prototype

Multi-nodal3 sensor nodes Data Refresh Rate1 Hz Node Size2” x 1.6 “ x 0.75 “ Sensor Temp. Range-60 to 1000 °C Board Temp. Range-40 to 125 °C Pressure Range0 to 15 psi Comm. Frequency2.4 GHz Prototype Specs

Software Wireless Star Network Topology Master-Slave Polling Scheme Multiple-Point Data Check Real-Time Data Monitoring Data Download – TCP/IP Interface Computer

X-Jet Testing Test multiple sensor types Test multiple transmitting nodes Collect pressure data inside chamber Measure temperature gradient in TPS

X-Jet Results Data matched control data from Ames data acquisition system Received data from multiple nodes during testing Obtained pressure data during X-Jet operation

Next step towards flight readiness Test of system functionality Collect pressure data for VAST VAST Flight »Sensor Nodes

No data has been retrieved from flash memory due to data corruption – Balloon rose slower than expected, causing it to land in a remote area – Battery power died in the middle of a flash write cycle leading to data corruption Solution: Next flight needs to have a timer implemented to stop writing data to memory before the power dissipates VAST Results

Programming complexity – Creating software libraries from scratch – No debugging equipment – Controlling the advanced ZigBee options – Integrating code from other sources Integration with VAST Scope was too broad in initial problem statement Challenges

Expanded upon previous year – Multi-nodal system – Multiple sensor types – Stand alone data storage Successful initial system testing in X-Jet VAST flight provided valuable lessons learned Next Step: Design and integration with re- entry platform Conclusion