Introduction
The James Webb Space Telescope, the most powerful space telescope ever constructed, has turned its unblinking eye toward Saturn’s largest moon, Enceladus, and made an astounding discovery: it has spotted monumental plumes of water vapor erupting from the moon’s surface. These jets of water vapor, with a length exceeding 9,000 kilometers, are painting a unique picture of Enceladus, allowing scientists to directly observe a phenomenon previously hidden from view.
A New Perspective on Enceladus
This groundbreaking observation signifies the first time that astronomers have been able to directly visualize water emissions from a Saturnian moon across such an enormous expanse. The implications of this discovery could be profound. NASA has indicated that this observation could shed light on the water supply mechanisms of Saturn’s entire system, including its complex ring structure.
Prior to the Webb Telescope’s involvement, other observatories had mapped jets of water vapor emanating from Enceladus, but they extended merely thousands of kilometers from the moon’s surface. However, Webb’s unprecedented sensitivity has brought forth a new narrative to this celestial saga.
Don't forget to water your planets ????
Webb provides new insight into how Enceladus' plumes act as a sprinkler system. The moon leaves a “donut” (torus) of water around Saturn as it orbits. About 30% of the water stays in that “donut." The rest is supplied to Saturn & its rings! pic.twitter.com/LaYjy3fZ5H
— NASA Webb Telescope (@NASAWebb) May 30, 2023
An Ocean World in Space
According to lead author Geronimo Villanueva, the data first appeared so astounding that he initially questioned its veracity. “I was just so shocked to detect a water plume more than 20 times the size of the moon. The water plume extends far beyond its release region at the southern pole,” he said.
Enceladus, nearly four percent the size of Earth with a diameter slightly over 500 kilometers, is an ocean world. This Saturnian moon houses a vast reservoir of salty water, trapped between its icy outer shell and rocky core. This icy moon’s surface is scarred with ‘tiger stripes’ – crevices from which geyser-like volcanoes launch jets of ice particles, water vapor, and organic chemicals into space.
A Staggering Rate of Emission
The new observations have revealed that Enceladus is propelling water vapor into space at an astonishing rate: about 79 gallons per second. This rate is so rapid that it could fill an Olympic-sized swimming pool in just a couple of hours.
Enceladus’ orbit around Saturn is relatively quick, at just 33 hours. As it hurtles around its parent planet, it leaves a ‘donut’ or halo of water in its wake. “In the Webb observations, not only was the plume huge, but there was just water absolutely everywhere,” Villanueva added.
Feeding Saturn’s Rings
NASA’s Cassini spacecraft had previously imaged the jet plumes on Enceladus as it flew through them, sampling their composition. What’s particularly interesting is that a significant proportion of the water emitted by Enceladus remains in Saturn’s outermost ring, known as the torus. The Webb Telescope’s observations have empirically demonstrated how the moon’s water vapor plumes feed the torus. Astronomers estimate that approximately 30 percent of the water stays within this ring structure.
The Webb Telescope continues to provide a unique tool for measuring how water evolves and changes over time across Enceladus’ massive plume. “As we see here, we will even make new discoveries and learn more about the composition of the underlying ocean,” concluded co-author Stefanie Milam.
As we peer into the cosmos with the James Webb Space Telescope, the secrets of the universe, including those held by the icy moons of distant planets, are gradually being unraveled. These discoveries not only satiate our curiosity but also underscore the endless possibilities that space exploration holds.
