HRDI observed the emission and absorption lines of molecular oxygen above the limb of the Earth, uses the Doppler shift of the lines to determine horizontal winds and uses the line shapes and strengths to obtain information about temperature and atmospheric make-up.
The instrument consists of two parts, the telescope and the interferometer which consists of an optical bench and support electronics.
The telescope used a narrow field of view to prevent Doppler shift variation across the field of view from distorting the results. Input from the telescope is fed to the processor via a fiber optic cable.
HRDI conducted scientific operations from November 1991 until April 2005.
