EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

A direct measurement of water vapor at Europa and implications for the magnetospheric environment

Lorenz Roth1, Lucas Paganini2,3, Geronimo Villanueva2, Avi Mandell2, Terry Hurford2, Michael Mumma2, Kurt Retherford4, and Aljona Blöcker1
Lorenz Roth et al.
  • 1KTH Royal Institute of Technology, School of Electrical Engineering and Computer Science, Space and Plasma Physics, Stockholm, Sweden (
  • 2NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 3American University, Washington, DC, USA
  • 4Southwest Research Institute, San Antonio, TX, USA

Previous investigations suggested local anomalies in Europa’s atmosphere, advancing the idea of possible water plumes. Now a global survey with the Keck observatory provided a direct detection (3.1 sigma) of line emission from H2O at infrared wavelengths on one out of 17 observing dates in 2016 and 2017. The non-detections on the 16 other dates resulted in sensitive upper limits for H2O abundance at various longitudes, providing reference to the rate and location of occurrence.

When active, outgassing at plumes locally increases the neutral density in Europa’s bound atmosphere. Such atmosphere anomalies in turn might lead to small scale (compared to Europa’s diameter) features in the electromagnetic interaction signals such as in magnetic field perturbations, or to an increased mass loss from Europa. The strength and detectability of plume-related magnetospheric signals depend on the relative abundance of plume gas (when active) compared to the sputtered atmosphere.

The new results from the infrared survey suggest that outgassing occurs at lower levels than previously estimated, with only rare localized events of somewhat stronger plume activity. In this presentation, we put these observations in context and discuss if and how plume activity might affect the magnetospheric environment.

How to cite: Roth, L., Paganini, L., Villanueva, G., Mandell, A., Hurford, T., Mumma, M., Retherford, K., and Blöcker, A.: A direct measurement of water vapor at Europa and implications for the magnetospheric environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7593,, 2020

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