NASA’s Cassini spacecraft has returned new images of Saturn’s moons Enceladus, Janus and Dione.
Cassini passed Enceladus first on March 27, according to the mission website. The encounter was primarily designed for Cassini’s ion and neutral mass spectrometer, which “tasted” the composition of Enceladus’ south polar plume. Other instruments, including the Cassini plasma spectrometer and composite infrared spectrometer, also took measurements.
Before the closest approach of this encounter, Cassini’s cameras imaged the plume, which is comprised of jets of water ice and vapor, and organic compounds emanating from the south polar region.
“More than 90 jets of all sizes near Enceladus’s south pole are spraying water vapor, icy particles, and organic compounds all over the place,” said Dr. Carolyn Porco, a leader of the Imaging Science team for NASA’s Cassini spacecraft. “Cassini has flown several times now through this spray and has tasted it. And we have found that aside from water and organic material, there is salt in the icy particles. The salinity is the same as that of Earth’s oceans.”
Dr. Porco believes Enceladus with its sub-surface liquid sea, organics, and an energy source, may host the same type of life we find in similar environments on Earth.
“The kind of ecologies Enceladus might harbor could be like those deep within our own planet,” Dr. Porco explained. “Abundant heat and liquid water are found in Earth’s subterranean volcanic rocks. Organisms in those rocks thrive on hydrogen (produced by reactions between liquid water and hot rocks) and available carbon dioxide and make methane, which gets recycled back into hydrogen. And it’s all done entirely in the absence of sunlight or anything produced by sunlight.”
Then, the spacecraft passed the small moon Janus with a closest approach distance of 44,000 km. And on March 28, Cassini flew by Dione and collected, among other observations, a nine-frame mosaic depicting the side of the moon that faces away from Saturn in its orbit.