Juno Explores Europa’s Oxygen Production through Measurements

Jupiter’s moon Europa has long fascinated scientists, as it’s believed to have a subsurface salty ocean that could potentially support extraterrestrial life. In a groundbreaking discovery, NASA’s Juno spacecraft has directly measured the rate of oxygen production on Europa’s surface for the first time. The findings, published in the journal Nature Astronomy, reveal that previous estimates of oxygen production were significantly higher than the actual rate observed.

Europa, the fourth largest moon of Jupiter, is composed of a rocky interior covered by a surface made of water ice. The presence of a salty ocean beneath the ice has been supported by measurements of the moon’s magnetic field collected by NASA’s Galileo mission. These “ocean worlds” are considered prime candidates for the search for life beyond Earth within our own solar system.

Lead author Jamey Szalay from Princeton University emphasizes the significance of Juno’s observations, stating, “Juno brought a new capability to directly measure the composition of charged particles shed from Europa’s atmosphere, and we couldn’t wait to further peek behind the curtain of this exciting water world.” On September 29, 2022, Juno observed Europa at an altitude of 353 kilometers using its Jovian Auroral Distributions Experiment (JADE) instrument.

The researchers found that charged particles from Jupiter’s magnetic field interact with Europa’s surface, breaking up water-ice molecules into hydrogen and oxygen. This process continuously erodes the icy shell of Europa, leading to the production of oxygen and hydrogen at the moon’s surface. The team determined the rate at which hydrogen is produced and estimated the total oxygen production on Europa to be around 12 kilograms per second.

These findings have important implications for the search for life on Europa. The researchers suggest that some of the produced oxygen could migrate through the ice sheet and reach the subsurface ocean, potentially supporting life. However, they note that the rate at which this occurs is lower than previously suggested in other studies.

The research conducted by Juno is part of its extended mission. Launched in 2011 and arriving at Jupiter in 2016, Juno completed its prime mission in July 2021. NASA authorized a mission extension to 2025, allowing Juno to contribute to future missions to the Jovian system.

The new findings are particularly relevant to the European Space Agency’s Jupiter Icy Moons Explorer (Juice) mission and NASA’s upcoming Europa Clipper. Juice, launched on April 14, 2023, is set to arrive at Jupiter in 2031. During its mission, Juice will study Europa and two other ocean-bearing moons, Ganymede and Callisto, to gain a better understanding of these intriguing worlds.

The Europa Clipper, scheduled for launch in October 2024, will also focus on studying Europa’s habitability. With nine science instruments onboard, the spacecraft will conduct 49 flybys to gather data about Europa’s surface and subsurface. The authors of the current study suggest that their findings may impact one of the instruments on the Europa Clipper, the Plasma Instrument for Magnetic Sounding.

Together, these missions will significantly enhance our knowledge of ocean worlds and their potential habitability. Co-author Robert Ebert of Southwest Research Institute remarks, “Europa is a good place to search for water within our solar system. Water is important for the existence of life and can be found in or on objects with varying characteristics.”

The discovery of oxygen production on Europa’s surface not only advances our understanding of this intriguing moon but also raises exciting prospects for the existence of life beyond our planet. Further exploration and mission advancements will continue to unveil the mysteries hidden within our solar system’s ocean worlds.