The High Resolution Dynamics Limb Sounder (HIRDLS) is an instrument on board the NASA Aura. It follows in the heritage of LRIR (Nimbus-6), LIMS and SAMS (Nimbus-7), ISAMS and CLAES (UARS). It was designed to observe global distribution of temperature and concentrations of O3, H2O, CH4, N2O, NO2, HNO3, N2O5, CFC-11, CFC-12, ClONO2, and aerosols in the upper troposphere, stratosphere, and mesosphere.
After launch, activation of the HIRDLS instrument revealed that the optical path was blocked so that 20% of the aperture could view the Earth's atmosphere. Engineering studies suggest that a piece of thermal blanketing material ruptured from the back of the instrument during the explosive decompression of launch. Attempts to remove this material mirror failed. However, even with the 80% blockage, measurements at high vertical resolution can be made at one scan angle.