EGU23-13324
https://doi.org/10.5194/egusphere-egu23-13324
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Seasonal variability of atomic hydrogen and oxygen in the EMM/EMUS cross-exospheric observations during Mars year 36

Susarla Raghuram1,2, Krishnaprasad Chirakkil1,2, Justin Deighan1, Michael Chaffin1, Sonal Jain1, Robert Lillis3, Marko Gacesa2,4, Matthew O. Fillingim3, David Brain1, Ed Thiemann1, Frank Eparvier1, Greg Holsclaw1, Scott England5, Scott Evans6, Fatma Hussain Lootah4, Hoor Abdelrahman Al Mazmi7, Shannon Curry3, and Hessa Rashid Al Matroushi8
Susarla Raghuram et al.
  • 1Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, CO, USA
  • 2Space and Planetary Science Center, Khalifa University, Abu Dhabi, UAE
  • 3Space Sciences Laboratory, University of California, Berkeley, CA, USA
  • 4Physics Department, Khalifa University, Abu Dhabi, UAE
  • 5Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
  • 6Computational Physics Inc. Springfield, Springfield, VA, United States
  • 7United Arab Emirates Space Agency, Abu Dhabi, UAE
  • 8Mohammed Bin Rashid Space Centre, Dubai, UAE

Atomic hydrogen and oxygen are the dominant species in the Martian exosphere. Atomic hydrogen is essentially produced from the dissociation of H2O, whereas, hot oxygen atoms are populated by non-thermal processes such as the dissociative recombination of O2+ with electrons in the Martian ionosphere. The study of these species helps to understand the evolution of the Martian atmosphere and more specifically the history of water on Mars.  The Emirates Mars Ultraviolet Spectrometer (EMUS), one of the primary instruments onboard the Emirates Mars Mission (EMM), has been observing atomic hydrogen and oxygen in the Martian exosphere over the Mars Year 36. We present the analysis of the cross-exospheric observations by the EMUS for hydrogen Lyman series and oxygen 130.4 nm emissions and their seasonal variability. The EMUS cross-exospheric observations cover the tangent altitude starting from 130 km to more than 35,000 km above the disk (see Fig. 1), with most of the observations below 25,000 km. The observations show that when Mars moved from perihelion to aphelion, the hydrogen emission line intensities increase by an order of magnitude or more whereas, for oxygen, it is an increment by a factor of about 2 at larger altitudes. Based on these observations, we also discuss the retrieval of densities, temperature, and the estimation of escape fluxes of hydrogen and oxygen species by applying 3D hydrogen ballistic corona and 3D Monte Carlo particle transport models, respectively.

Figure 1: The EMM-observed cross-exosphere emission intensity profiles of atomic hydrogen and oxygen during Mars Year 36

How to cite: Raghuram, S., Chirakkil, K., Deighan, J., Chaffin, M., Jain, S., Lillis, R., Gacesa, M., Fillingim, M. O., Brain, D., Thiemann, E., Eparvier, F., Holsclaw, G., England, S., Evans, S., Lootah, F. H., Al Mazmi, H. A., Curry, S., and Al Matroushi, H. R.: Seasonal variability of atomic hydrogen and oxygen in the EMM/EMUS cross-exospheric observations during Mars year 36, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13324, https://doi.org/10.5194/egusphere-egu23-13324, 2023.