Saturn’s moon Enceladus is shrouded in a thick layer of snow. In some places, the downy stuff is 700 meters deep, new research suggests.
“It’s like Buffalo, but worse,” says planetary scientist Emily Martin, referring to the famously snowy city in New York. The snow depth suggests that Enceladus’ dramatic plume may have been more active in the past, Martin and colleagues report in the Mar. 1 Icarus.
Planetary scientists have been fascinated by Enceladus’ geysers, made up of water vapor and other ingredients, since the Cassini spacecraft spotted them in 2005 (SN: 12/16/22). The spray probably comes from a salty ocean beneath an icy shell.
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Some of that water goes to form one of Saturn’s rings (SN: 5/2/06). But most of it falls back onto the moon’s surface as snow, Martin says. Understanding the properties of that snow — its thickness and how dense and compact it is — could help reveal Enceladus’ history, and lay groundwork for future missions to this moon.
“If you’re going to land a robot there, you need to understand what it’s going to be landing into,” says Martin, of the National Air and Space Museum in Washington, D.C.
To figure out how thick Enceladus’ snow is, Martin and colleagues looked to Earth — specifically, Iceland. The island country hosts geological features called pit chains, which are lines of pockmarks in the ground formed when loose rubble such as rocks, ice or snow drains into a crack underneath (SN: 10/23/18). Similar features show up all over the solar system, including Enceladus.
Previous work suggested a way to use geometry and the angle at which sunlight hits the surface to measure the depth of the pits. That measurement can then reveal the depth of the material the pits sit in. A few weeks of fieldwork in Iceland in 2017 and 2018 convinced Martin and her colleagues that the same technique would work on Enceladus.
Using images from Cassini, Martin and colleagues found that the snow’s thickness varies across Enceladus’ surface. It is hundreds of meters deep in most places and 700 meters deep at its thickest.
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It’s hard to imagine how all that snow got there, though, Martin says. If the plume’s spray was always what it is today, it would take 4.5 billion years — the entire age of the solar system — to deposit that much snow on the surface. Even then, the snow would have to be especially fluffy.
It seems unlikely that the plume switched on the moment the moon formed and never changed, Martin says. And even if it did, later layers of snow would have compressed the earlier ones, compacting the whole layer and making it much less deep than it is today.
“It makes me think we don’t have 4.5 billion years to do this,” Martin says. Instead, the plume might have been much more active in the past. “We need to do it in a much shorter timeframe. You need to crank up the volume on the plume.”
The technique was clever, says planetary scientist Shannon MacKenzie of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. Without rovers or astronauts on the ground, there’s no way to scoop up the snow and see how far down it goes. “Instead, the authors are very cleverly using geology to be their rovers, to be their shovels.”
MacKenzie was not involved in the new work, but she led a mission concept study for an orbiter and lander that could one day visit Enceladus. One of the major questions in that study was where a lander could safely touch down. “Key to those discussions was, what do we expect the surface to be?” she says. The new paper could help “identify the places that are too fluffy to land in.”
Source link Snow has become synonymous with the season of winter and the cold temperatures this season brings.
However, the concept of snow is much more than just the weather on cold and frosty days. In the depths of space, and miles away from Earth, one of Saturn’s moons, Enceladus, has been found to be blanketed in an unusual layer of snow – something remarkably different to what we experience here on Earth.
Located hundreds of thousands of kilometres away from Earth, Enceladus is a frozen celestial object which orbits around Saturn. It grows only 310 miles in diameter which makes it the 17th largest moon out of 81 known natural satellites around the planet.
As Enceladus is distant from the sun, it has very cold temperatures which have hardened the surface of the moon. The temperatures on the surface range from 287°F to -362°F, which has resulted in a thick layer of snowseas forming on its surface. This layer is estimated to be up to 40 miles deep and primarily consists of frozen water, with a small amount of dust, dirt, and ice.
Surprisingly, Enceladus is also home to some form of life as it was discovered to have not only a thick layer of snow but also a global ocean of liquid saltwater below the icy surface. This salty water is believed to contain a variety of microorganisms, which suggests that Enceladus is a potential location for the existence of life in our solar system.
In conclusion, while snow remains an integral part of our winter season here on Earth, it also has the remarkable ability to define other locations in our solar system – with the icy moon of Enceladus blanketed in a thick layer of snow. This snow not only gives the moon its own unique beauty, but it may hold the secret to the existence of other forms of life.