The Emirates eXploration Imager (EXI) onboard the Emirates Mars Mission (EMM): Overview of In-flight Performance, and Water Ice Cloud Retrievals

The EXI instrument is a camera onboard the EMM spacecraft, with a field a view capable capturing the full disk of Mars throughout its nominal science orbit.   Though the use of its multiple band passes (220, 260, 320, 437, 546, 635 nm) and the effective spatial resolution (2–4 km per native pixel), EXI’s primary goal is to provide both regional and global imaging of the Martian atmosphere with diurnal sampling over much of the planet on a time scale of approximately 10 days.  This presentation will provide an overview of EXI’s on-orbit instrument performance, a brief description of the observation strategy employed with the start of Science Operations (23-May-2021, Ls=49°), and the retrieval results of the ice optical depth and their diurnal behavior for the period of mid-spring through late-summer in the northern hemisphere.  More specifically, the presentation will cover:

 

• Status of the instrument calibration and plans for on-going on-orbit monitoring of instrument performance, including radiometric errors. Plus, some guidance on interpreting the metadata of the EXI publicly released raw and calibrated images;

 

• Illustration of the various disk geometries sampled during an EMM orbit of Mars, and how such observations are combined to provide diurnal coverage of the illuminated portion of the disk/atmosphere;

 

• Overview of the ice optical depth retrieval algorithm, and its application to the data obtained since the start Science Operations with an emphasis on the behavior of the aphelion cloud belt; including the formation and decay phases.