A study of Europa's atmosphere, conducted during the Juno mission, reveals that the moon's water-ice surface, exposed to its space environment, dissociates into molecular hydrogen (H₂) and oxygen (O₂), which are primary atmospheric constituents. These species are produced by charged particles breaking molecular bonds in surface ice, leading to the release of H₂ and O₂. The study confirms that H₂⁺ and O₂⁺ pickup ions are dominant atmospheric components, with O₂ production estimated at 12 ± 6 kg s⁻¹, less than previously thought. This process is the dominant exogenic surface erosion mechanism on Europa, surpassing meteoroid impacts. The atmosphere is primarily composed of H₂ and O₂, with H₂ being more abundant. The observed PUIs (pickup ions) show a non-thermal, escaping population, indicating that the neutral atmosphere is not fully thermalized. The study also finds that electron impact ionization is the dominant loss mechanism for H₂, with a total loss rate of 0.16 ± 0.04 kg s⁻¹. These findings suggest that Europa's atmospheric oxygen production is lower than previously estimated, providing a narrower range for habitability in its subsurface ocean. The study highlights the importance of direct observations for understanding Europa's atmospheric composition and its interaction with Jupiter's magnetosphere. The results have implications for future missions like Europa Clipper and JUICE, emphasizing the need for careful interpretation of PUI data. The study also provides insights into the atmospheric processes on Europa, including the role of radiolysis in dissociating water ice and the transport of neutral species. The findings contribute to the understanding of Europa's surface chemistry and its potential for hosting life.A study of Europa's atmosphere, conducted during the Juno mission, reveals that the moon's water-ice surface, exposed to its space environment, dissociates into molecular hydrogen (H₂) and oxygen (O₂), which are primary atmospheric constituents. These species are produced by charged particles breaking molecular bonds in surface ice, leading to the release of H₂ and O₂. The study confirms that H₂⁺ and O₂⁺ pickup ions are dominant atmospheric components, with O₂ production estimated at 12 ± 6 kg s⁻¹, less than previously thought. This process is the dominant exogenic surface erosion mechanism on Europa, surpassing meteoroid impacts. The atmosphere is primarily composed of H₂ and O₂, with H₂ being more abundant. The observed PUIs (pickup ions) show a non-thermal, escaping population, indicating that the neutral atmosphere is not fully thermalized. The study also finds that electron impact ionization is the dominant loss mechanism for H₂, with a total loss rate of 0.16 ± 0.04 kg s⁻¹. These findings suggest that Europa's atmospheric oxygen production is lower than previously estimated, providing a narrower range for habitability in its subsurface ocean. The study highlights the importance of direct observations for understanding Europa's atmospheric composition and its interaction with Jupiter's magnetosphere. The results have implications for future missions like Europa Clipper and JUICE, emphasizing the need for careful interpretation of PUI data. The study also provides insights into the atmospheric processes on Europa, including the role of radiolysis in dissociating water ice and the transport of neutral species. The findings contribute to the understanding of Europa's surface chemistry and its potential for hosting life.