Windswept piles of dust, or layers of ice? To be able to make clear the composition of a mysterious area on Mars, ESA’s Mars Categorical has revisited it. The brand new findings counsel layers of water ice stretching miles under floor. It’s essentially the most water ever discovered on this a part of the planet. ESA published this story originally on January 18, 2024. Edits by EarthSky.
Miles-thick buried ice on Mars?
Over 15 years in the past, the European House Company’s Mars Express spacecraft studied the Medusae Fossae Formation on Mars, revealing huge deposits as much as 1.5 miles (2.5 km) deep. It was unclear what the deposits have been made from, from these earlier observations. However new analysis now has a solution: it’s ice.
Thomas Watters of the Smithsonian Establishment in Washington D.C. is lead creator of each the brand new analysis and the preliminary 2007 research. He mentioned:
We’ve explored this area once more utilizing newer information from Mars Categorical’s MARSIS radar. And we discovered the deposits to be even thicker than we thought: as much as 2.2 miles (3.7 km) thick. Excitingly, the radar indicators match what we’d anticipate to see from layered ice, and are much like the indicators we see from Mars’s polar caps, which we all know to be very ice wealthy.
The total space of the Medusae Fossae Formation is the same as 20% the dimensions of the continental United States. These scientists mentioned that, if melted, the ice locked up on this area would cowl Mars in a layer of water about 5 ft to about 9 ft deep (1.5 to 2.7 m deep).
It’s essentially the most water ever discovered on this a part of Mars, and sufficient to fill Earth’s Purple Sea.

Alternating layers of ice
The Medusae Fossae Formation consists of a number of wind-sculpted options measuring lots of of kilometers throughout and a number of other kilometers excessive. Discovered on the boundary between Mars’s highlands and lowlands, the options are probably the most important single supply of dust on Mars, and one of the crucial in depth deposits on the planet.
Preliminary observations from Mars Categorical confirmed the Medusae Fossae Formation to be comparatively clear to radar and low in density, each traits we’d see from icy deposits. Nonetheless, scientists couldn’t rule out a drier chance: that the options are literally big accumulations of windblown dust, volcanic ash or sediment.
The brand new research’s co-author Andrea Cicchetti of the Nationwide Institute for Astrophysics in Italy defined:
Right here’s the place the brand new radar information is available in! Given how deep it’s, if the Medusae Fossae Formation was merely a large pile of dust, we’d anticipate it to grow to be compacted beneath its personal weight. This might create one thing far denser than what we really see with MARSIS. And after we modeled how totally different ice-free supplies would behave, nothing reproduced the properties of the Medusae Fossae Formation.
We’d like ice.
The brand new outcomes as a substitute counsel layers of dust and ice, all topped by a protecting layer of dry dust or ash a number of hundred meters thick.
Future exploration and collaboration
Though Mars now seems to be an arid world, the planet’s floor is filled with indicators that water was as soon as plentiful, together with dried-up river channels, historic ocean and lake beds, and water-carved valleys. We’ve additionally discovered vital shops of water ice on Mars, akin to the large polar caps, buried glaciers nearer the equator, and near-surface ice laced by means of martian soil.
Large shops of ice close to the equator – akin to these suspected to lurk under the dry floor of the Medusae Fossae Formation – couldn’t have fashioned within the planet’s current local weather. They should have fashioned in a earlier local weather epoch. Colin Wilson, ESA undertaking scientist for Mars Categorical and the ESA ExoMars Hint Fuel Orbiter, mentioned:
This newest evaluation challenges our understanding of the Medusae Fossae Formation, and raises as many questions as solutions. How way back did these ice deposits kind, and what was Mars like at the moment? If confirmed to be water ice, these huge deposits would change our understanding of Mars local weather historical past.
Any reservoir of historic water can be a captivating goal for human or robotic exploration.
A useful resource for future Mars explorers?
The extent and site of those icy Medusae Fossae Formation deposits would additionally make them probably very beneficial for our future exploration of Mars. Missions to Mars might want to land close to the planet’s equator, removed from the ice-rich polar caps or high-latitude glaciers. And so they’ll want water as a useful resource. So discovering ice on this area is sort of a necessity for human missions to the planet. However Colin Wilson mentioned:
Sadly, these Medusae Fossae Formation deposits are lined by lots of of meters of dust, making them inaccessible for no less than the following few a long time. Nonetheless, each little bit of ice we discover helps us construct a greater image of the place Mars’s water has flowed earlier than, and the place it may be discovered as we speak.
Whereas Mars Categorical maps water ice to a depth of some kilometers, a view of near-surface water is offered by Mars orbiter TGO. This orbiter is carrying the FREND instrument, which is mapping hydrogen – an indicator of water ice – within the topmost metre of martian soil. FREND noticed a hydrogen-rich space the dimensions of the Netherlands inside Mars’s Valles Marineris in 2021, and is at the moment mapping how shallow water deposits are distributed throughout the Purple Planet. Wilson added:
Collectively, our Mars explorers are revealing an increasing number of about our planetary neighbor.

Backside line: Planetary scienetists knew, from an earlier research, that the Medusae Fossae Formation close to Mars’ equator had huge buried deposits of some materials. However was unclear what the deposits have been made from, from these early observations. However new analysis now has a solution: it’s ice.