On-orbit Calibration and Performance of the EMIT Imaging Spectrometer

The Earth Mineral Dust source InvesTigation (EMIT) is a remote orbital visible shortwave infrared (VSWIR) imaging spectrometer, also known as a hyperspectral imager. This article describes the EMIT spectroradiometric calibration and on-orbit validation experiments. EMIT was launched to the International Space Station in July 2022, beginning a year-long mission to map the mineralogy of Earth’s mineral dust forming regions. It achieves several notable firsts for an instrument of its class. It demonstrates successful on-orbit adjustments of FPA alignment with sub-micron precision. It offers spectral uniformity better than 98%. Optical artifacts in the measurement windows of the spectrum are at least three orders of magnitude below the primary signal. EMIT consists of just a handful of optical elements, no shutter, and no onboard calibration systems. With this simple and efficient design, EMIT satisfies the stringent needs for the next generation of VSWIR imaging spectrometers, demonstrating that tomorrow’s spectral measurements are now possible with contemporary technology.