Juno Mission Reveals Europa’s Oxygen Production Rate Lower Than Expected
In a groundbreaking discovery, scientists with NASA’s Juno mission to Jupiter have found that the rate of oxygen production on Jupiter’s icy moon Europa is significantly lower than previously estimated. The findings, published in Nature Astronomy on March 4, were derived from data collected by the spacecraft’s Jovian Auroral Distributions Experiment (JADE) instrument, which measured hydrogen outgassing from Europa’s surface.
According to the paper’s authors, Europa generates approximately 26 pounds (12 kilograms) of oxygen per second. This is a stark contrast to previous estimates, which ranged from a few pounds to over 2,000 pounds per second. The discovery has important implications for understanding the moon’s potential for supporting life.
Europa, the fourth largest of Jupiter’s 95 known moons and the smallest of the four Galilean satellites, has long fascinated scientists due to its vast internal ocean of salty water beneath its icy crust. The moon’s location within Jupiter’s radiation belts is also of interest. Charged particles from Jupiter bombard Europa’s surface, splitting water molecules and generating oxygen. Some of this oxygen may find its way into the moon’s subsurface ocean, potentially serving as a source of metabolic energy.
“Europa is like an ice ball slowly losing its water in a flowing stream. Except, in this case, the stream is a fluid of ionized particles swept around Jupiter by its extraordinary magnetic field,” explains JADE scientist Jamey Szalay from Princeton University. “When these ionized particles impact Europa, they break up the water-ice molecule by molecule on the surface to produce hydrogen and oxygen. In a way, the entire ice shell is being continuously eroded by waves of charged particles washing up upon it.”
The Juno spacecraft captured this phenomenon during its close flyby of Europa on September 29, 2022. As Juno flew within 220 miles (354 kilometers) of the moon, JADE identified and measured hydrogen and oxygen ions created by the bombarding charged particles. This direct measurement provided scientists with a tight constraint on the amount of oxygen produced on Europa’s icy surface.
Scott Bolton, Juno’s principal investigator, emphasizes the significance of these findings. “Back when NASA’s Galileo mission flew by Europa, it opened our eyes to the complex and dynamic interaction Europa has with its environment,” says Bolton. “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.”
While the Juno mission has made significant contributions to our understanding of Europa, there is still much more to explore. NASA’s upcoming Europa Clipper mission, set to arrive at Jupiter in 2030, will investigate various facets of the moon, including its potential habitability. Equipped with nine state-of-the-art science instruments, the mission aims to determine if Europa has conditions suitable for life.
As the Juno mission team sets its sights on another Jovian moon, Io, they anticipate gathering valuable data that will contribute to our knowledge of this volcanic world. On April 9, the spacecraft will come within approximately 10,250 miles (16,500 kilometers) of Io’s surface. This data, combined with past flybys, will provide scientists with a comprehensive understanding of Io’s unique features.
The Juno mission continues to push the boundaries of scientific exploration, shedding light on the mysteries of Jupiter and its fascinating moons. With each new discovery, our understanding of the solar system expands, bringing us closer to answering age-old questions about the potential for life beyond Earth.
