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The Emirates Mars Ultraviolet Spectrometer (EMUS), aboard the Emirates Mars Mission (EMM), has been conducting observations of ultraviolet emissions within the Martian exosphere. Taking advantage of the distinctive orbit of the EMM around Mars, EMUS utilizes a dedicated strafe observation strategy to scan the illuminated Martian exosphere at tangential altitudes ranging from 130 to over 20,000 km. To distinguish between emissions of Martian origin and those from the interplanetary background, EMUS conducts specialized background observations by looking away from the planet. This approach has allowed us to investigate the radial and seasonal variations in Martian coronal emission features at H Lyman‐α, βand γwavelengths. Our analysis supports the previous studies indicating that Martian exospheric hydrogen Lyman emission brightness attains its highest levels around the southern summer solstice and reaches its lowest levels when Mars is near aphelion. Additionally, a secondary peak emission at all altitudes is observed after perihelion during Martian Year (MY) 36, which can be attributed to a Class C dust storm. Our study establishes a strong correlation between solar flux and coronal brightness for these emissions, highlighting the impact of solar activity on the visibility of Martian corona. In addition, we have examined interannual variability and found that emission intensities in MY 37 surpassed those in MY 36, primarily due to increased solar activity. These observations help to understand potential seasonal patterns of exospheric hydrogen, which is driven by underlying mechanisms in the lower atmosphere and solar activity, eventually suggesting an impact on water loss in the Martian atmosphere. Atomic hydrogen primarily forms as a product when Martian water undergoes various photochemical reactions. These hydrogen atoms encircle Mars and become illuminated by solar radiation, leading to the creation of Martian hydrogen corona. The Emirates Mars Ultraviolet Spectrometer (EMUS), on the Emirates Mars Mission spacecraft, is currently studying the Martian atmosphere using the ultraviolet light emissions of different atoms and molecules on Mars. In this study, we have analyzed EMUS observations and determined that atomic hydrogen emission intensities increase during the Martian southern summer and decrease as Mars moves farther away from the Sun. Furthermore, we have compared the hydrogen brightness between two consecutive Martian years and have found that the hydrogen brightness is higher in the most recent year primarily due to increased solar radiation. These observations help us understand possible patterns that occur during different seasons on Mars and the mechanisms underlying water loss in the Martian atmosphere. We present the variability in Martian atomic hydrogen brightness from early Martian year (MY) 36 to the first quarter of MY 37Martian exospheric H Ly‐βand γemissions reach their peak brightness during the southern summer of MY 36Martian corona is much brighter at H Ly‐βwavelength in MY 37 compared to the previous year due to increased solar irradiance We present the variability in Martian atomic hydrogen brightness from early Martian year (MY) 36 to the first quarter of MY 37 Martian exospheric H Ly‐βand γemissions reach their peak brightness during the southern summer of MY 36 Martian corona is much brighter at H Ly‐βwavelength in MY 37 compared to the previous year due to increased solar irradiance

The Emirates Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) Hope probe images Mars at wavelengths extending from approximately 100 to 170 nm. EMUS observations began in February 2021 and cover over a full Mars year. We report the first limb scan observations at Mars of ultraviolet emissions Ar I 106.6 nm, N I 120 nm, and carbon monoxide (CO) Fourth Positive Group (A− X) band system excited by electron impact on CO. We use EMUS limb scan observations to retrieve number density profiles of argon, molecular nitrogen, atomic oxygen, and CO in the upper atmosphere of Mars from 130 to 160 km. CO is a sensitive tracer of the thermal profile and winds in Mars' middle atmosphere and the chemistry that balances CO2in the atmosphere of Mars. EMUS insertion orbit special observations demonstrate that far ultraviolet limb measurements of the Martian thermosphere can be spectroscopically analyzed with a robust retrieval algorithm to further quantify variations of CO composition in the Martian upper atmosphere. This study focuses on satellite observations of ultraviolet light by the Emirates Mars Ultraviolet Spectrometer onboard the Emirates Mars Mission. The observed ultraviolet light is generated by argon, oxygen, nitrogen, and carbon monoxide and is used to determine the abundance of these gases in the upper atmosphere of Mars (130–160 km). We present the first remotely sensed measurements of argon and carbon monoxide abundances in the upper atmosphere of Mars. Mean retrieved argon, nitrogen, and oxygen densities, respectively, are lower than general circulation model predictions and other direct measurements by 10%–15%, ∼75%, and 35%–55%. Carbon monoxide densities measured for the first time agree qualitatively with measurements by other instruments and model predictions for similar conditions. We demonstrate that ultraviolet observations can be analyzed with a robust technique to further quantify variations of carbon monoxide abundance in the Martian upper atmosphere. Remotely sensed CO densities retrieved from 130 to 160 km for the first time are ∼45% lower than MCD 6.1 predictions for similar conditionsMean retrieved Ar, N2, and O densities from 130 to 160 km are lower than MCD 6.1 and NGIMS by 10%–15%, ∼75%, and 35%–45%, respectivelyHigh spectral resolution observations by EMM EMUS show the first detection of C I 119.3 nm emission blended with N I 120 nm emission Remotely sensed CO densities retrieved from 130 to 160 km for the first time are ∼45% lower than MCD 6.1 predictions for similar conditions Mean retrieved Ar, N2, and O densities from 130 to 160 km are lower than MCD 6.1 and NGIMS by 10%–15%, ∼75%, and 35%–45%, respectively High spectral resolution observations by EMM EMUS show the first detection of C I 119.3 nm emission blended with N I 120 nm emission