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, but worse,” says planetary scientist Emily Martin, referring to the famously snowy metropolis in New York. The snow depth means that Enceladus’ dramatic plume might have been extra energetic up to now, Martin and colleagues report within the Mar. 1 Icarus.
Planetary scientists have been fascinated by Enceladus’ geysers, made up of water vapor and different substances, for the reason that 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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Some of that water goes to type one in all Saturn’s rings (SN: 5/2/06). But 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.
“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 work out how thick Enceladus’ snow is, Martin and colleagues regarded to Earth — particularly, Iceland. The island nation hosts geological options known as pit chains, that are strains of pockmarks within the floor shaped when unfastened rubble corresponding to rocks, ice or snow drains right into a crack beneath (SN: 10/23/18). Similar options present up all around the photo voltaic system, together with Enceladus.
Pit chain craters in Iceland, like these proven right here, helped planetary scientist Emily Martin and colleagues confirm that they might measure the depth of craters on Enceladus. Martin took this picture throughout a subject tour.E. Martin
Previous work advised a approach 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 number of weeks of fieldwork in Iceland in 2017 and 2018 satisfied Martin and her colleagues that the identical method would work on Enceladus.
Using photos from Cassini, Martin and colleagues discovered that the snow’s thickness varies throughout Enceladus’ floor. It is a whole bunch of meters deep in most locations and 700 meters deep at its thickest.
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It’s arduous to think about how all that snow obtained there, although, Martin says. If the plume’s spray was all the time what it’s right now, it might take 4.5 billion years — your complete 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 shaped 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 now.
“It makes me think we don’t have 4.5 billion years to do this,” Martin says. Instead, the plume may need been rather more energetic up to now. “We need to do it in a much shorter timeframe. You need to crank up the volume on the plume.”
The method was intelligent, says planetary scientist Shannon MacKenzie of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. Without rovers or astronauts on the bottom, there’s no method 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 concerned within the new work, however she led a mission idea research for an orbiter and lander that might in the future go to Enceladus. One of the main questions in that research was the place a lander might safely contact down. “Key to those discussions was, what do we expect the surface to be?” she says. The new paper might assist “identify the places that are too fluffy to land in.”