Europa – NASA/Wikipedia
NASA’s Juno spacecraft has directly measured electrically charged oxygen and hydrogen molecules from the atmosphere of Europa, one of Jupiter’s largest moons. These observations provide important constraints on the oxygenation potential of the subsurface ocean, according to a new study co-authored by SwRI scientists and led by Princeton University.
“These findings have direct implications for Europa’s potential habitability,” said SwRI’s Scott Bolton, Ph.D., Juno principal investigator and co-author of the study. “This study provides the first direct in-situ measurements of the water content present in Europa’s atmosphere and reveals a narrow range that may support habitability.”
In 2022, Juno completes a flyby of Europa, bringing it 352 kilometers closer to the moon. The SwRI-developed Jupiter Auroral Distribution Experiment (JADE) instrument aboard Juno detected significant amounts of charged molecular oxygen and hydrogen missing from the atmosphere.
“For the first time, we are able to clearly detect hydrogen and oxygen in situ measurements, further confirming that Europa’s atmosphere is primarily made up of hydrogen and oxygen molecules,” said SwRI staff scientist and co-author. said Dr. Robert Evert. .
The source of these molecules is thought to be water ice on Europa’s surface.Jupiter’s intense radiation destroys H2The molecular bond of O leaves oxygen and hydrogen. Heavier oxygen molecules remain largely bound up in the atmosphere at or near the earth’s surface, while lighter hydrogen primarily escapes into and out of the atmosphere. Oxygen produced in the ice is either lost from the atmosphere or sequestered at the surface. Oxygen held in Europa’s ice could reach the underground ocean as a potential source of metabolic energy.
“Europa’s ice shell absorbs radiation, protecting the ocean below. This absorption also produces oxygen within the ice, so in a sense, the ice shell acts as Europa’s lungs, protecting the ocean below. “It provides a potential source of oxygen for the human body,” said Dr. Jamie Zareh, lead author of the study and a researcher at Princeton University. “We currently have a narrow limit on total oxygen production on Europa, about 12 kg per second. Before Juno, previous estimates ranged from a few kg per second to more than 1,000 kg per second. This discovery clearly shows that oxygen is being produced continuously at the Earth’s surface, but in slightly lower amounts than expected.”
“We designed JADE to measure the charged particles that produce Jupiter’s auroras,” said SwRI staff scientist and co-author Dr. Frederick Allegrini. “A flyby of Europa was not part of Juno’s primary mission. JADE is designed to operate in high radiation environments, but it won’t necessarily work in Europa’s environment, which is constantly exposed to high levels of radiation. . Nevertheless, the instruments played beautifully.”
The new measurements contribute to a deeper understanding of Europe and its environment and open the door to newer and more accurate models. For example, the study’s new estimates of how much oxygen is produced within Europa’s surface could inform future research related to its subsurface ocean and potential habitability. be. These observations provide the first measurements of charged particle composition in Europa’s vicinity and provide an important new window into the complex interactions of the satellite with its environment.
“Europa is an interesting object because scientists are convinced that there is a liquid ocean inside it,” Evert said. “Water is important for the existence of life and exists inside or on the surface of objects with a variety of characteristics. Europa is the perfect place to look for water in the solar system.”
The paper, “Oxygen production from dissociation of Europa’s water ice surface,” is published in Nature Astronomy. https://www.nature.com/articles/s41550-024-02206-x. (open access)
For more information, please visit: https://www.swri.org/planetary-science.
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