Saturn’s moon Enceladus is shrouded in a thick layer of snow. In some locations, the downy stuff is 700 meters deep, new analysis suggests.
“It’s like Buffalo, however worse,” says planetary scientist Emily Martin, referring to the famously snowy metropolis in New York. The snow depth means that Enceladus’ dramatic plume may have been more active in the past, Martin and colleagues report within the Mar. 1 Icarus.
Planetary scientists have been fascinated by Enceladus’ geysers, made up of water vapor and other ingredients, because the Cassini spacecraft noticed them in 2005 (SN: 12/16/22). The spray in all probability comes from a salty ocean beneath an icy shell.
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A few of that water goes to form one of Saturn’s rings (SN: 5/2/06). However most of it falls again onto the moon’s floor as snow, Martin says. Understanding the properties of that snow — its thickness and the way dense and compact it’s — might assist reveal Enceladus’ historical past, and lay groundwork for future missions to this moon.
“When you’re going to land a robotic there, it’s good to perceive what it’s going to be touchdown into,” says Martin, of the Nationwide Air and Area Museum in Washington, D.C.
To determine how thick Enceladus’ snow is, Martin and colleagues regarded to Earth — particularly, Iceland. The island nation hosts geological options referred to as pit chains, that are strains of pockmarks within the floor fashioned when unfastened rubble equivalent to rocks, ice or snow drains right into a crack beneath (SN: 10/23/18). Related options present up everywhere in the photo voltaic system, together with Enceladus.
Earlier work recommended a means to make use of geometry and the angle at which daylight hits the floor to measure the depth of the pits. That measurement can then reveal the depth of the fabric the pits sit in. A few weeks of fieldwork in Iceland in 2017 and 2018 satisfied Martin and her colleagues that the identical method would work on Enceladus.
Utilizing photographs from Cassini, Martin and colleagues discovered that the snow’s thickness varies throughout Enceladus’ floor. It’s tons of of meters deep in most locations and 700 meters deep at its thickest.
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It’s exhausting to think about how all that snow acquired there, although, Martin says. If the plume’s spray was at all times what it’s right this moment, it could take 4.5 billion years — the whole age of the photo voltaic system — to deposit that a lot snow on the floor. Even then, the snow must be particularly fluffy.
It appears unlikely that the plume switched on the second the moon fashioned and by no means modified, Martin says. And even when it did, later layers of snow would have compressed the sooner ones, compacting the entire layer and making it a lot much less deep than it’s right this moment.
“It makes me assume we don’t have 4.5 billion years to do that,” Martin says. As an alternative, the plume might need been rather more lively up to now. “We have to do it in a a lot shorter timeframe. You might want to crank up the quantity on the plume.”
The method was intelligent, says planetary scientist Shannon MacKenzie of the Johns Hopkins College Utilized Physics Laboratory in Laurel, Md. With out rovers or astronauts on the bottom, there’s no technique to scoop up the snow and see how far down it goes. “As an alternative, the authors are very cleverly utilizing geology to be their rovers, to be their shovels.”
MacKenzie was not concerned within the new work, however she led a mission idea research for an orbiter and lander that would in the future go to Enceladus. One of many main questions in that research was the place a lander might safely contact down. “Key to these discussions was, what will we anticipate the floor to be?” she says. The brand new paper might assist “determine the locations which can be too fluffy to land in.”