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On-board temperature calibration for space vehicles

NPL have teamed up with RAL Space to investigate calibration options for the thermocouples, such as using a very small ingot of gallium to provide a known, and reliable, reference temperature.

The need

Non-contact temperature sensors are commonly deployed on board space-bound vehicles, such as satellites. As they cannot be manually recalibrated, blackbodies have also been included to provide method of calibration.

Although the blackbodies can be used regularly and autonomously the cavity temperature must be measured in order to use them, which requires resistance thermometers. These too can easily be affected by the conditions in space, and hence are not as reliable as necessary.

The impact

NPL have teamed up with RAL Space to investigate calibration options for the thermocouples, such as using a very small ingot of gallium to provide a known, and reliable, reference temperature which can provide an in-situ calibration of the resistance thermometers that is traceable to the ITS-90. The melting temperature of gallium is well established.

NPL have been able to show that the miniature ingot can be used in this situation, and with as little as 0.5 g of metal. It is suitable for possible inclusion in a flight mission.

With this new technology in place, it is expected that there will be significant improvements in the accuracy, stability and traceability of temperature measurements in the space sector, which in turn will underpin climate studies.

Read more about contact thermometry

Read more about non-contact thermometry