Two scientists from the Southwest Research Institute (SwRI) played a significant role in a recent observation conducted by the James Webb Space Telescope (JWST). The team observed a massive plume of water vapor, stretching over 6,000 miles, emanating from Saturn’s moon Enceladus. This discovery has led to SwRI’s Dr. Christopher Glein receiving a Cycle 2 allocation to study the plume and key chemical compounds on the moon’s surface. The goal is to gain a better understanding of the potential habitability of this intriguing ocean world.
Enceladus has been a subject of interest due to its dynamic nature and its potential for hosting extraterrestrial life. During the Cassini spacecraft’s mission, which spanned 13 years and focused on the Saturn system, it was revealed that Enceladus possesses a subsurface ocean of liquid water. Cassini collected samples of ice grains and water vapor from plumes erupting from cracks in the icy surface of the moon.
Dr. Glein, an expert in extraterrestrial oceanography, emphasized the significance of Enceladus in the search for life beyond Earth. He expressed continued amazement at the discoveries made on this extraordinary moon since the Cassini mission began.
The recent observations made with JWST’s Near InfraRed Spectrograph have once again yielded remarkable results. The data revealed a plume on Enceladus that extends far beyond what was previously imagined, measuring more than 20 times the diameter of the moon. The sensitivity of JWST allowed for the visualization of how the moon’s plumes contribute to the water supply of the entire Saturn system, including its iconic rings. As Enceladus orbits Saturn in just 33 hours, it releases water vapor, creating a halo-like structure in its wake. Approximately 30 percent of the water remains in the moon’s wake, while the remaining 70 percent escapes to supply the rest of the Saturnian system.
Dr. Silvia Protopapa, another member of the SwRI team, highlighted how the JWST observations visually illustrate the role played by Enceladus’ water vapor plumes in the formation of the torus. She expressed her enthusiasm for being part of the Cycle 2 team and their search for new indications of habitability and plume activity on Enceladus.
Inspired by the remarkable findings from JWST’s initial glimpse of Enceladus, Dr. Glein will lead the team in observing the moon again in the coming year. The objective is to search for specific indicators of habitability, such as organic signatures and hydrogen peroxide. The presence of hydrogen peroxide is of particular interest, as it can provide potent sources of metabolic energy. The previous Cassini mission did not provide a definitive answer regarding the availability of such strong oxidants on Enceladus.
These new observations will significantly enhance the search for habitability indicators on the moon’s surface. They will improve the signal-to-noise ratio by up to ten times compared to Cycle 1. Understanding the variability of plume outgassing over time is also crucial for planning future planetary science missions targeting the plume.
Dr. Glein sees JWST as a valuable bridge between the Cassini mission and the proposed search-for-life mission called Orbilander. After Cycle 2, the team hopes to gain a better understanding of whether ocean samples are widely distributed across Enceladus’ surface or primarily concentrated near the south pole. This information could aid in determining if Orbilander can access ocean samples near the equator, potentially expediting future missions to Enceladus.
The team’s findings were accepted for publication in Nature Astronomy on May 17, 2023, and a pre-print version of the paper is available.
Source: Southwest Research Institute