Juno Mission Discovers Surprising Oxygen Levels on Jupiter’s Moon Europa
Jupiter’s moon Europa has always been a source of fascination for scientists, with its icy surface and potential for hosting life. Now, the Juno mission to Jupiter has provided us with groundbreaking insights into Europa’s atmosphere, shedding light on its habitability.
The results of the mission, published in Nature Astronomy, have revealed that Europa’s icy surface produces less oxygen than previously believed. This discovery challenges our understanding of the moon’s potential to sustain life.
Europa has long been considered one of the most habitable worlds in our solar system. Evidence from the Galileo mission has shown that beneath its icy exterior lies a vast ocean, containing twice the amount of water as Earth’s oceans. This ocean is in contact with the moon’s rocky floor, creating an environment conducive to chemical water-rock interactions that could produce energy necessary for life.
Telescope observations have also provided intriguing clues about Europa’s potential for hosting life. The presence of a weak, oxygen-rich atmosphere and intermittent plumes of water erupting from the ocean suggest the possibility of basic chemical elements on the moon’s surface. These elements, including carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur, are essential for life as we know it on Earth. Some of these elements could seep down into the water from the atmosphere and surface.
The heating of Europa and its ocean is primarily due to the moon’s orbit around Jupiter, which generates tidal forces that warm an otherwise frigid environment. This combination of water, the right chemical elements, and a source of heat makes Europa an enticing candidate for hosting life.
However, despite these promising conditions, scientists are still uncertain whether there has been enough time for life to develop on Europa. The same uncertainty applies to Mars, another prime candidate for extraterrestrial life. The upcoming Rosalind Franklin rover mission to Mars in 2028 aims to explore the possibility of past or present life on the red planet.
Another contender for hosting life in our solar system is Saturn’s moon Enceladus. The Cassini-Huygens mission discovered plumes of water emanating from a sub-surface salty ocean, also in contact with rock at the ocean’s floor. This finding further fuels the excitement surrounding the potential for life beyond Earth.
In fourth place is Saturn’s moon Titan, which boasts a thick atmosphere filled with organic compounds, including hydrocarbon and tholins. These compounds, formed in the high atmosphere, eventually make their way down to the moon’s surface, creating an environment rich in the building blocks of life.
Returning to Europa, the Juno mission has provided crucial insights into the moon’s oxygen levels. By utilizing advanced charged particle instruments, Juno can measure the energy, direction, and composition of charged particles on Europa’s surface. Similar instruments used in missions to Saturn and Titan found organic substances called tholins, as well as particles suggesting the presence of atmospheres on Saturn’s moons Rhea and Dione.
The measurements taken by Juno indicate the presence of pickup molecular oxygen and hydrogen ions from Europa’s surface and atmosphere. Some of these ions escape into space, while others hit the icy surface, enhancing the amount of oxygen present. However, the measurements also reveal that Europa’s surface produces only about 12kg of oxygen per second, which is at the lower end of previous estimates ranging from 5kg to 1,100kg per second.
This discovery implies that Europa’s surface undergoes minimal erosion. The measurements suggest that only 1.5cm of Europa’s surface erodes per million years, which is significantly less than previously believed. Consequently, Europa is constantly losing oxygen due to pickup processes, with only a small amount being replenished and ending up back on the surface.
The implications of these findings for Europa’s potential to host life are significant. Some of the oxygen trapped in the surface may find its way to the subsurface ocean, potentially nourishing any life present there. However, based on the study’s estimates, the overall loss of oxygen should be less than the previously estimated range of 0.3kg to 300kg per second.
It remains to be seen whether the rate recorded on September 29, 2022, is representative of the moon’s overall oxygen levels. Factors such as plume eruptions, orbital position, and upstream conditions may influence the rate at different times. To further investigate Europa’s habitability, upcoming missions like NASA’s Europa Clipper and the Juice mission will provide more detailed measurements and insights.
The Juno mission has undoubtedly expanded our understanding of Europa’s atmosphere and its potential for hosting life. While the discovery of lower oxygen levels challenges previous assumptions, it also highlights the complexity of studying distant worlds and the need for further exploration. As we continue to unravel the mysteries of our solar system, Europa remains a captivating destination in our search for extraterrestrial life.
This article is republished from The Conversation under a Creative Commons
