Europa and Ganymede's Water-Product Exospheres

Apurva Oza (1) , François Leblanc (2) , Jean-Yves Chaufray (1) , Carl Schmidt (3) , L. Roth (4) , R. E. Johnson (5, 6) , T.A. Cassidy (7, 8) , L. Leclercq (9) , Ronan Modolo (1)

1 HELIOS - LATMOS
2 PLANETO - LATMOS
3 BU - Boston University [Boston]
4 KTH - Royal Institute of Technology [Stockholm]
5 MS - Department of Materials Science and Engineering [Charlottesville]
6 Department of Physics [New York]
7 Department of Astronomy [Charlottesville]
8 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
9 Engineering Physics Program [Charlottesville]

Europa and Ganymede are thought to possess globally similar exospheres, in spite of the possibility that Europa is currently cryovolcanically active, and Ganymede's intrinsic magnetic field. Ions in Jupiter's magnetosphere bombard the icy surfaces, and produce predominantly O₂, with slightly less H₂O and H₂ due to freezing and escape respectively. We investigate and compare the water-product exospheres of the two satellites under rotation, using our 3-D Exosphere Global Model (EGM). In previous works ([1], [2]), we focused on the near-surface z < 1.25r_s , oxidized component of the exosphere, dominated by thermal-ized O₂ , which undergoes a dusk-over-dawn asymmetry due to diurnal solar insolation of the surface over the satellite's orbit. This was observed by asymmetries in oxygen aurorae. Here, we focus on characterizing the hydrogen-species: H, H₂ , and H₂O which have been far more elusive as lyman-α auroral emission has multiple production pathways, even in the absence of endogenic sources.

Domains: Sciences of the Universe [physics]

Apurva Oza, François Leblanc, Jean-Yves Chaufray, Carl Schmidt, L. Roth, et al.. Europa and Ganymede's Water-Product Exospheres. European Planetary Science Congress 2017, Sep 2017, Riga, Latvia. pp.EPSC2017-626-1. ⟨insu-01665604⟩