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The MEADS pressure transducers are manufactured by Stellar Technologies, Inc. and are derivatives of off-the-shelf transducers. They are strain gage-type transducers with a range from 0 to 5 psia, outfitted at the manufacturer with flight electrical connectors, pressure input fittings, and mounting brackets. The transducers are not thermally compensated and they contain no electronics (electronics functions are performed by the SSE.) The transducers were calibrated with the SSE, as a subsystem, in combination with thermal/vacuum qualification at Langley. The calibration coefficients from this testing were then used to convert millivolts to pressures when the MEADS flight data was obtained. All of the hardware-related uncertainties were used in an error budget to ensure that the MEADS subsystem would meet the science objectives listed above.4
process is described in detail in Reference 4. In order for the MEDLI project to be allowed to install the MEADS pressure ports in the thermal protection heatshield, MSL required flight-like testing to demonstrate that pressure ports would not adversely affect the MSL spacecraft performance. Since pressure ports have never been installed in an ablating, planetary entry heatshield to measure surface pressures during entry, an extraordinary amount of arc jet testing was required to demonstrate compliance with MSL requirements. In addition, the MEDLI project needed to determine if pressures could be accurately measured in an ablating, pyrolyzing heatshield material. This resulted in a research and development test effort in addition to a demonstration test program to verify both the “do no harm” and the performance requirements of the pressure ports in the MSL heatshield.
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