Using the sensitivity of the James Webb Space Telescope, astronomers have detected an enormous plume of water vapor pouring out from the south pole of Saturn’s moon Enceladus, a jet extending nearly 10,000 kilometers (6,000 miles) that feeds a previously detected torus that circles the entire ocean. planet.
Water vapor from a putative subsurface ocean beneath Enceladus’ icy crust has been seen before in stunning images collected by Saturn’s Cassini spacecraft, but not at the scale revealed by Webb. Observations indicate that water vapor is jetted at 300 liters (79 gal) per second.
“When I was looking at the data, at first, I was thinking I must be wrong,” said Geronimo Villanueva of NASA’s Goddard Space Flight Center, lead author of a paper accepted by Nature Astronomy. “It was absolutely shocking to discover a water column more than 20 times the size of the Moon. The water column extends far beyond its launch area at the South Pole.”
Enceladus is only 4 percent the size of Earth and has a diameter of about 500 kilometers (313 miles). It is believed to harbor a global ocean of salt water sandwiched between a rocky core and an icy outer crust, making it a prime target for future searches for life beyond Earth. Water vapor, ice particles, and organic compounds are constantly emitted from ice fissures near the moon’s south pole.
“Enceladus’ orbit around Saturn is relatively fast, only 33 hours,” Villanueva said. “As it orbits Saturn, the moon and its jets essentially spew water out, leaving behind a halo, almost like a donut. In Webb’s notes, not only was the plume huge, there was just water everywhere.”
The torus of water vapor fed by geysers on Enceladus is co-located with Saturn’s dense outer E ring. Webb’s observations show that about 30 percent of the water remains in the torus while the remainder escapes to feed the rest of the Saturnian system.
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