NASA and Lockheed launched the Juno space probe in 2011 as part of the New Frontiers program. It entered Jupiter’s orbit on July 4th, 2016, to peek beneath the planet’s dense clouds. Now, in its extended mission, the probe is taking a closer look at the planet’s largest moon: Europa.
Juno has directly measured charged oxygen and hydrogen molecules in Europa’s atmosphere, according to a study co-authored by Southwest Research Institute (SwRI) scientists and researchers from Princeton University. These observations provide information on the potential oxygenation of the moon’s subsurface ocean.
“This study provides the first direct in-situ measurement of water components existing in Europa’s atmosphere, giving us a narrow range that could support habitability,” said Juno Principal Investigator Dr. Scott Bolton of SwRI, a co-author of the study. “These findings have direct implications on the potential habitability of Europa.”
SwRI developed the Jovian Auroral Distributions Experiment (Jade) instrument aboard Juno that detected the oxygen and hydrogen lost from Europa’s atmosphere. Jupiter’s radiation breaks H2O’s molecular bonds, leaving oxygen and hydrogen behind. The oxygen is heavier than the hydrogen, so it remains closer to the surface while the hydrogen escapes.
Scientists believe that these molecules come from water ice on Europa’s surface.
“Europa’s ice shell absorbs radiation, protecting the ocean underneath. This absorption also produces oxygen within the ice, so in a way, the ice shell acts as Europa’s lung, providing a potential oxygen source for the ocean.” said Princeton University Research Scholar Dr. Jamey Szalay, the study’s lead author. “…The findings unambiguously demonstrate oxygen is continuously produced in the surface, just a good bit lower than we expected.”
Juno and Jade’s measurements are helping researchers form a more in-depth understanding of Europa’s environment. For example, the new estimation of oxygen production on the moon’s surface could inform future research on the possibility of human habitability.
The paper “Oxygen production from dissociation of Europa’s water ice surface,” appears in Nature Astronomy: https://www.nature.com/articles/s41550-024-02206-x.
