The Emirates Exploration Imager (EXI) Instrument on the Emirates Mars Mission (EMM) Hope Mission

Abstract

The Emirates Exploration Imager (EXI) on-board the Emirates Mars Mission (EMM) offers both regional and global imaging capabilities for studies of the Martian atmosphere. EXI is a framing camera with a field-of-view (FOV) that will easily capture the martian disk at the EMM science orbit periapsis. EXI provides 6 bandpasses nominally centered on 220, 260, 320, 437, 546, 635 nm using two telescopes (ultraviolet (UV) and visible(VIS)) with separate optics and detectors. Images of the full-disk are acquired with a resolution of 2–4 km per pixel, where the variation is driven by periapsis and apoapsis points of the orbit, respectively. By combining multiple observations within an orbit with planetary rotation, EXI is able to provide diurnal sampling over most of the planet on the scale of 10 days. As a result, the EXI dataset allows for the delineation of diurnal and seasonal timescales in the behavior of atmospheric constituents such as water ice clouds and ozone.This combination of temporal and spatial distinguishes EXI from somewhat similar imaging systems, including the Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) (Malin et al. in Icarus 194(2):501–512, 2008) and the various cameras on-board the Hubble Space Telescope (HST; e.g., James et al. in J. Geophys. Res. 101(E8):18,883–18,890, 1996; Wolff et al. in J. Geophys. Res. 104(E4):9027–9042, 1999). The former, which has comparable spatial and spectral coverage, possesses a limited local time view (e.g., mid-afternoon). The latter, which provides full-disk imaging, has limited spatial resolution through most of the Martian year and is only able to provide (at most) a few observations per year given its role as a dedicated, queue-based astrophysical observatory. In addition to these unique attributes of the EXI observations, the similarities with other missions allows for the leveraging of both past and concurrent observations. For example, with MARCI, one can build on the ∼6 Mars years of daily global UV images as well as those taken concurrently with EXI.

Diurnal Variability in EMIRS Daytime Observations of Water Ice Clouds During Mars Aphelion‐Season

“…Seasonal differences in the spatial distribution of water ice cloud were primarily observed in the post-conjunction period after L s = 120°, during which the early morning latitudinal extension to the north of the nominal ACB latitude band was most evident. This behavior was also observed by the Emirates Exploration Imager (EXI) instrument onboard EMM (Jones et al, 2021), and is discussed further by Wolff et al (2022, this issue). By the nominal end of the ACB at L s = 140° optical depths showed decreases at all times of day.…”

EMIRS Observations of the Aphelion‐Season Mars Atmosphere

“…Clear diurnal variations in atmospheric temperatures and water ice cloud opacity were evident in the retrievals (Atwood et al., 2022; Fan et al., 2022). Detailed analysis of these retrieval results, especially in conjunction with results obtained from the two other instruments on‐board EMM, the Emirates Exploration Imager (Jones et al., 2021) and the Emirates Mars Ultraviolet Spectrometer (Holsclaw et al., 2021), will improve our understanding of the underlying physical processes that operate in the current Mars atmosphere, while also helping to validate and tune general circulation models. Systematic EMIRS observations continue as the part of the baseline set of ongoing EMM mission activities promising exciting new information as we enter the dusty perihelion season.…”

Diurnal Variations in the Aphelion Cloud Belt as Observed by the Emirates Exploration Imager (EXI)

“…There are two instruments onboard that sample the lower atmosphere, typically through column integrated optical depths: Emirates eXploration Imager (EXI; Jones et al. (2021)) and Emirates Mars InfraRed Spectrometer (EMIRS; Edwards et al. (2021)).…”