New radar imaging by ESA's Mars Express mission strongly suggests that a vast amount of ice, up to 3.7 km thick, lies beneath the surface near the equator. The ice if melted would cover Mars with an ocean 2.7 m deep.
Layers of ice and dust lie below a crust of hardened ash and dust 100s of meters thick.
The deposits are located in the Medusae Fossae Formation, a large geological formation ~5,000 km along the equator. See maps below.
This graphic shows the estimated thickness of ice along a line across the Eumenides Dorsum.
The area was scanned by MARSIS, the Mars Express Radar for Sub-surface and Ionospheric Sounding.
The graph shows the shape of the land and the structure of the subsurface, with the layer of dry sediments (likely dust or volcanic ash) in brown and the layer of suspected ice-rich deposits in blue. The graph shows that the ice deposit is several km high and 100s of km wide!
This is a significant finding of ice deposits near the equator, which would be more accessible to future crewed missions to Mars than the ice near the poles.
However, extracting the dust-contaminated water-ice thru the thick layer of dust will require some heavy machinery. NASA has been exploring concepts for such ice and water recovery on Mars for years.
The graphic below shows one such concept using a Mobile Drilling/Transport Rig (MDTR) + cryobot equipment.
4 billion years ago, Mars lost its magnetosphere. The solar wind (charged particles from the Sun) stripped away the atmosphere. Surface liquid water evaporated into space, merged with minerals or became underground ice.
This artist’s impression shows how Mars may have looked about 4 billion years ago. The young planet would have had enough water to cover its entire surface about 140 m deep.
Here is a video of a flyover over a section of the Medusae Fossae Formation on Mars based on images taken by the High Resolution Imaging Science Experiment (HiRISE) camera on board NASA's Mars Reconnaissance Orbiter (MRO).
Part of the explanation for ice at lower latitudes on Mars is its axis tilt (aka obliquity) varying over time, by as much as 60 deg.
During high obliquity periods, ice evaporates from the poles and falls as snow at lower latitudes building layers of ice. CO2 sublimation increases atmos. pressure leading to liquid water.
The reverse happens at low obliquity. Some of the ice layers at lower latitudes get buried under dust and survive.
@hittitezombie
If you covert that volume to liters, you get 3.9E17 liters, i.e.,
390,000,000,000,000,000 liters.
Plus there is several times more water at the poles.
Enough to sustain a small human population? (Assuming we can solve all the other problems of travel, survival, oxygen, food, energy, materials, etc for living on Mars).
@AkaSci It's not "confirming" that it is ice, not at all.
It is confirming their circa-2007 discovery that there is a lot of buried material that has a low dielectric constant. There has been significant work since then suggesting that it's probably volcanic tuff, considering that it is in the middle of the Tharis volcanic province.
@simonbp
The authors of the study state -
"The presence of subsurface reflectors is consistent with a multi-layer structure of an ice-poor cap above an ice-rich unit analogous to the Martian Polar Layered Deposits. The volume of an ice-rich component across the entire MFF below a 300–600 m dry cover corresponds to a global equivalent layer of water of ∼1.5 to ∼2.7 m or ∼30%–50% of the total estimated in the North Polar cap."
Perhaps, "confirming" is too strong a word, maybe "strong evidence"?
@AkaSci I'm trying to understand this. If this is how much water Mars has left, as frozen groundwater, is it possible to extrapolate back how much it had in the past?
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