The experiment on the ISS with low-temperature fixed points – a stage in developing high-stable on-board fixed-point blackbodies for in-flight calibrating the Earth observation IR instruments

The in-flight experiment “Reper-Kalibr” was conducted on board the International Space Station, in which the fixed points referenced to melt transition temperatures of the gallium eutectic alloys Ga-In (~288,8 К), Ga-Sn (~293,6 К), Ga-Zn (~298,3 К) and the Ga (~302,9 K) were investigated. Investigation of zero-gravity impact on the low-temperature fixed points characteristics is required to develop an on-orbit calibration scale within the range ~(210–350) K for creating in the end high-stable on-board fixed-point blackbodies designed for the space-based IR instruments in-flight calibration. The main experimental results are the series of melt plateaus in cycles of melt – freeze of the selected substances. The experiment has shown that the selected fixed points are useful for achieving said object. The comparative analysis of the results of ground-based and in-flight stages of the experiment is performed.