Abstract
Future orbital sensors to monitor global climate require low drift rates for onboard thermometry, which is currently unattainable without on-orbit recalibration. Phase change materials (PCM), such as those that make up the ITS-90 standard, are seen as the most reliable references on the ground and could be good candidates for orbital recalibration. Space Dynamics Lab (SDL) has been developing miniaturized phase change references capable of deployment on an orbital blackbody for nearly a decade. Recently, SDL has been developing flight phase change cells for the Radiation Budget Instrument (RBI) and has conducted a phase change cell experiment with ITS-90 standard material gallium on the International Space Station (ISS). This presentation will discuss performance of the phase change cells during ground testing and on the ISS. Ground testing shows melt curves are repeatable to a few mK, the phase change cell equilibrates to the blackbody to within a few mK when unpowered, and phase change cell performance is stable over four years. The flight results shows the consistency of the Ga melt point from the ground to on-orbit.
Phase Change Cells
Future orbital sensors to monitor global climate require low drift rates for onboard thermometry, which is currently unattainable without on-orbit recalibration. Phase change materials (PCM), such as those that make up the ITS-90 standard, are seen as the most reliable references on the ground and could be good candidates for orbital recalibration. Space Dynamics Lab (SDL) has been developing miniaturized phase change references capable of deployment on an orbital blackbody for nearly a decade. Recently, SDL has been developing flight phase change cells for the Radiation Budget Instrument (RBI) and has conducted a phase change cell experiment with ITS-90 standard material gallium on the International Space Station (ISS). This presentation will discuss performance of the phase change cells during ground testing and on the ISS. Ground testing shows melt curves are repeatable to a few mK, the phase change cell equilibrates to the blackbody to within a few mK when unpowered, and phase change cell performance is stable over four years. The flight results shows the consistency of the Ga melt point from the ground to on-orbit.