MicroStrain® Wireless Sensor Network to Monitor Acoustic Shock During NASA Shuttle Launch

Table of Content

Introduction
Web Based Data Management
Wireless Sensor Network
Scalable Platform
About MicroStrain, Inc.

Introduction

There is a significant impact on safety of ground facilities, spacecraft and equipment caused by the noise produced from the rocket exhaust during shuttle launch events.

Safe operation of exposed systems is threatened by accumulated stress. MicroStrain and NASA Kennedy Space Center researchers worked together to implement a wireless sensor solution. The solution allowed internet-based monitoring of far-field shuttle launch acoustics. Figure 1 shows the shuttle launch of Altantis from Kennedy Space Center.

Figure 1. Shuttle Launch of Atlantis from Kennedy Space Center on July 8th, 2011. Acoustic and vibration generated by rocket propulsion is harmful to spacecraft, surrounding facilities, and equipment. (Photo Courtesy NASA/Bill Ingalls)

Test results confirmed prediction models with precise, easily accessible field data. Also the sensor network deployed offers NASA with a foundation to implement a remote scalable sensor network that can monitor high-value, hazardous systems proactively.

The key objective of the NASA rocket acoustics program is the monitoring of hazardous systems in a remote manner. One specific system of interest for NASA is the composite overwrapped pressure Vessel (COPV) used for housing different kinds of pressurized fluids. COPVs are subject to internal pressure and proximity to shuttle launch.

When these systems fail, there is a considerable threat to mission assurance and safety. Due to limited accessibility and extreme operating conditions, traditional hardwired solutions cannot monitor the strain experienced by these hazardous systems. A range of systems were considered by NASA and it was found that MicroStrain's sensing solutions satisfied all their needs for this specific project.

The focus of MicroStrain’s project with NASA was on computing the impact of vibration and acoustics on far-field equipment. Stringent mission protocols restrained researchers from accessing the test area for a number of days before and after the launch. Uncertainty with regards to launch sequence initiation timing complicated testing conditions further.

Consequently, it was required that deployed sensor systems are alert and powered anticipating a window of launch time.

These conditions required that wireless sensor networks operate on a limited amount of power, while still offering a measurement frequency that can capture the brief but dynamic nature of launch acoustics.

Web Based Data Management

The continuous collection of information over this time period generates an enormous amount of data that becomes difficult to transfer and navigate. For identifying and analyzing key threshold data, powerful data management strategies are needed. The solution from MicroStrain addresses the data collection concerns and test environment considerations presented by the NASA project by combining high-performance wireless nodes, advanced power management techniques and its novel web based data management platform, SensorCloud®. This is shown in Figure 2.

Figure 2a. SensorCloud visualization of shuttle launch data

Figure 2b. MicroStrain SG-Link wireless strain node

Figure 2c. MicroStrain G-Link wireless accelerometer node

Using MicroStrain sensors and sensor services combined, NASA researchers could monitor remotely the far-field acoustic, pressure and vibration levels of the STS-134 Endeavour and STS-135 Atlantis launches at the Kennedy Space Center.

Wireless Sensor Network

MicroStrain offered NASA all the needed hardware, software, and support to deploy a wireless sensor system in this application. The system hardware consisted of two wireless G-Link® acceleration nodes, one wireless SG-Link® strain gauge, a wireless WSDA® data collection base station, and SensorCloud®.

Nodes were installed on a cantilever plate with low natural frequency. Installation of the plate was done on Shuttle PAD 39B which is adjacent to Shuttle PAD 39A where the last several launches took place. At this area the plate is exposed to vibrational and acoustic launch effects, around 7000ft from the Shuttle liftoff and where far-field acoustics are of interest.

Prior calculations done by NASA showed the peak acoustic loads at various instances, however, these levels were not used for determining damage effects. After the spacecraft was launched successfully, data reduction was used for isolating the sensor data for the launch event.

First data was collected on a PC. After the five-day measurement timeframe, it was observed that the computer has obtained more than 3GB worth of data. The issue of viewing, navigating and sharing large amounts of data was addressed by NASA by uploading it to SensorCloud. On SensorCloud, MicroStrain support engineers and NASA researchers partnered to seek and study key threshold data.

Two acceleration data sets from MicroStrain SG-Link strain gauges clearly showed peak vibration levels. Results allowed NASA to calculate the equivalent static load developed by the rocket and correlate the data to analyze predictions.

Figure 3. Microstrain sensor nodes mounted to test plate. Wires connect NASA patch sensors to MicroStrain wireless network

Scalable Platform

In addition to model validation, the value of the sensor network to NASA researchers includes the ability to wirelessly scale across several locations and equipment types. In cases where researchers do not have the needed access to maintain wired networks.

In this manner, MicroStrain’s sensor solution can save precious NASA resources by proactively measuring strains exerted on high-value and potentially hazardous assets, such as COPVs. Smart data management brings down potential maintenance costs and prevents premature replacement or failure. The result allows improved safety of monitored components and is a tool to support any issues of availability and maintainability of equipment and structures by condition.

About MicroStrain, Inc.

MicroStrain, Inc. make tiny sensors that are used in a wide range of applications, including knee implants, civil structures, advanced manufacturing, unmanned military vehicles, and automobile engines. Microstrain offers wireless sensors. MicroStrain develops and produces innovative, smart, wireless, microminiature displacement, orientation, and force sensors.

MicroStrain, Inc. have introduced a broader line of micro-displacement sensors that could withstand extreme temperatures, hundreds of millions of cycles, and complete submersion in saline. The aerospace and automotive industry found our sensors met their requirements, and this company have worked on many groundbreaking projects. The products by MicroStrain, Inc. include Displacement Transducers, Inclinometers, Wireless Sensors, Force Probes, Dataloggers and Signal Conditioners.

This information has been sourced, reviewed and adapted from materials provided by MicroStrain, Inc.

For more information on this source, please visit MicroStrain, Inc.

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