Enceladus is roofed in thick snow

Saturn’s moon Enceladus is covered in thick snow. In some places, the soft stuff is 700 meters deep, new research suggests.

“It’s like Buffalo, but worse,” said planetary scientist Emily Martin, referring to New York’s famous snowy city.Snow depths suggest dramatic plume on Enceladus may have been more active in the pastIn a March 1 report by Martin and colleagues Icarus.

Planetary scientists are fascinated by Enceladus’ geysers, made of water vapor and other ingredientsSince the Cassini spacecraft discovered them in 2005 (Serial Number: 12/16/22). The spray probably came from the Aral Sea beneath the ice crust.

some water flows to forming one of saturn’s rings (Serial Number: 5/2/06). But much of it falls back to the lunar surface as snow, Martin said. Knowing the properties of that snow — how thick it is and how dense and dense it is — could help reveal Enceladus’ history and lay the groundwork for future missions to the moon.

“If you’re going to land a robot there, you need to understand where it’s going to land,” said Martin of the National Air and Space Museum in Washington, D.C.

To find out how thick Enceladus’ snowpack is, Martin and his colleagues looked at Earth — specifically Iceland.This island nation has the pit chainthe pock lines that form on the ground when loose debris such as rock, ice, or snow flows into cracks below (Serial Number: 10/23/18). Similar features appear throughout the solar system, including Enceladus.

Previous work proposed a method for measuring the depth of pits using geometry and the angle at which the sun hits the surface. This measurement can then reveal the depth of the material where the dimples are located. Several weeks of fieldwork in Iceland In 2017 and 2018, Martin and her colleagues believed that the same technique would work on Enceladus.

Using images from Cassini, Martin and colleagues found that the snow cover on Enceladus’ surface varies in thickness. Most of them are hundreds of meters deep, and the thickest part is 700 meters.

Still, Martin said, it’s hard to imagine how the snow got there. If the plume’s spray had been the way it is today, it would have taken 4.5 billion years — the age of the entire solar system — to deposit that much snow on the surface. Even then, the snow has to be extra fluffy.

Martin said it seems unlikely that the plume started at the moment the moon was forming and never changed. Even then, later snow layers would have compressed earlier snow layers, compacting the entire snow layer to a much smaller depth than it is today.

“It makes me think we don’t have 4.5 billion years to do this,” Martin said. Instead, the plume may have been more active in the past. “We need to do it in less time. You need to turn up the volume of the plume.”

The technique is clever, says Shannon MacKenzie, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. Without rovers or astronauts on the ground, there’s no way to shovel snow and see how far it’s falling. “Instead, the authors very cleverly use geology as their rover, as their shovel.”

MacKenzie was not involved in the new effort, but she is leading a mission concept study of an orbiter and lander that could one day visit Enceladus. One of the main questions of the study was where the lander could land safely. “The key to these discussions is, what do we expect to surface?” she said. The new paper could help “identify places that are too fluffy to land.”