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Evidence of fresh ice in the northern hemisphere



Infrared eyes on Enceladus: evidence of fresh ice in the northern hemisphere

In these detailed infrared images of Saturn̵

7;s icy moon Enceladus, reddish areas indicate fresh ice that has deposited on the surface. Photo credit: NASA / JPL-Caltech / University of Arizona / LPG / CNRS / University of Nantes / Space Science Institute

Scientists used data collected by NASA’s Cassini spacecraft during 13 years of research into the Saturn system to create detailed images of the icy moon – and to reveal geological activity.

New composite images from NASA’s Cassini spacecraft are the most detailed global infrared views ever of Saturn’s moon Enceladus. And the data used to create these images provides strong evidence that the moon’s northern hemisphere has resurfaced with ice from within.

Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) collected light that was reflected from Saturn, its rings, and its ten great icy moons – light that is visible to both humans and infrared light. VIMS then separated the light into its different wavelengths, information that tells scientists more about the composition of the reflective material.

The VIMS data, along with detailed images captured by Cassini’s Imaging Science Subsystem, were used to create Enceladus’ new global spectral map.

Cassini scientists discovered in 2005 that Enceladus – which to the naked eye looks like a highly reflective, brilliant white snowball – shoots huge clouds of ice grains and steam from an ocean that lies beneath the icy crust. The new spectral map shows that infrared signals clearly correlate with this geological activity, which is easy to see at the South Pole. There the so-called “tiger stripes” cracks blow ice and steam from the inner ocean.

However, some of the same infrared features also occur in the northern hemisphere. This shows the scientists not only that the northern area is covered with fresh ice, but that the same geological activity – a renewal of the landscape – has taken place in both hemispheres. Surface renewal in the north may be due to either icy rays or a more gradual movement of the ice through fractures in the crust from the subterranean ocean to the surface.

“The infrared shows us that the surface of the South Pole is young, which is no surprise as we knew about the jets blowing up icy material there,” said Gabriel Tobie, VIMS scientist at the University of Nantes in France and co-author of the new research published in Icarus.

“Now, thanks to those infrared eyes, you can go back in time and say that a large region in the northern hemisphere also appears young and was probably active in geological timelines not so long ago.”

Managed by NASA’s Jet Propulsion Laboratory in Southern California, Cassini was an orbiter that observed Saturn for more than 13 years before it ran out of fuel. The mission immersed it in the planet’s atmosphere in September 2017, in part to protect Enceladus, which has the potential to maintain viable conditions, with its ocean likely to be warmed and churned by hydrothermal vents such as those on Earth’s ocean floor.


Closest north views of Saturn’s moon Enceladus


Provided by the Jet Propulsion Laboratory



Quote: Infrared eyes on Enceladus: indications of fresh ice in the northern hemisphere (2020, September 19), accessed on September 19, 2020 from https://phys.org/news/2020-09-infrared-eyes-enceladus-hints -fresh.html

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