Engineering of the HiWIND Thermospheric Wind Observatory

The High Altitude Observatory has developed and flown the HiWIND Thermospheric Wind Observatory on it's 2nd circumpolar flight out of Kiruna, Sweden in June of 2018. This was its second science flight following it's original deployment in 2011. HiWIND measures neutral daytime thermospheric winds and temperatures using doppler shifted and broadened spectral emission lines from atomic oxygen at 630nm. This science is enabled by flying a high altitude balloon at 40km where scattered sunlight is only 0.1% of that at sea-level. The instrument uses a Fabry-Pérot étalon to acquire high resolution emission line spectra using a scientific grade CCD. A rotating mirror is used to capture emission line signals from one of four orthogonal directions in a process that repeats throughout the 5 day mission. This paper will describe the gondola construction approach as well as an overview of the solar panel/battery charging system and the thermal control system which allowed these long duration science observations.