Red Sea worth of water buried near Mars equator?

18 Jan 2024

Medusae Fossae on Mars. Image: ESA/DLR/FU Berlin

Ice present near the Red Planet’s equator, if melted, could cover the entire planet in a 2.7m deep puddle, according to data from ESA’s Mars Express mission.

A space exploration mission commissioned by the European Space Agency (ESA) has helped confirm the presence of extensive amounts of water on the surface of Mars in the form of ice.

The Medusae Fossae Formation or MFF, one of the most mysterious features in the topography of the Red Planet present around its equator, was re-examined using data collected from a radar on the ESA Mars Express, the agency’s first planetary mission launched in 2003.

When the MFF was first studied by the Mars Express around 15 years ago, scientists observed massive deposits up to 2.5km deep – but they weren’t sure of its composition. Now, they’re certain it’s ice.

“We’ve explored the MFF again using newer data from Mars Express’s MARSIS radar and found the deposits to be even thicker than we thought: up to 3.7km thick,” said Thomas Watters of the Smithsonian Institution, lead author of the new research and the initial 2007 study.

MARSIS, or Mars Advanced Radar for Subsurface and Ionosphere Sounding, has previously shown that the south polar region of Mars is made of many layers of ice and dust down to a depth of 1.5km in an area 200km wide.

“Excitingly, the radar signals match what we’d expect to see from layered ice and are similar to the signals we see from Mars’s polar caps, which we know to be very ice rich,” Watters added.

According to a release published by the ESA today (18 January), the MFF consists of features measuring “hundreds” of kilometres across and several kilometres high. Scientists suspect this is the biggest single source of dust on Mars.

‘No ice’ theory bites the dust

Now that they are certain the deposits consist of extensive amounts of water – enough to fill the Red Sea on Earth – interspersed with layers of dust, the ESA estimates that the ice locked up in the MFF could cover all of Mars in a layer of water up to 2.7m deep.

Initial observations from Mars Express showed the deposits to be relatively transparent to radar and low in density – which is typically associated with ice. But scientists wondered if the deposits could actually be dust, volcanic ash or sediment.

“Here’s where the new radar data comes in! Given how deep it is, if the MFF was simply a giant pile of dust, we’d expect it to become compacted under its own weight,” said co-author Andrea Cicchetti of the National Institute for Astrophysics in Italy.

“This would create something far denser than what we actually see with MARSIS. And when we modelled how different ice-free materials would behave, nothing reproduced the properties of the MFF – we need ice.”

According to the ESA, the extent and location of these icy MFF deposits make them valuable for future explorations of Mars because missions will need to land near the planet’s equator and will require water as a resource.

“Unfortunately, these MFF deposits are covered by hundreds of metres of dust, making them inaccessible for at least the next few decades,” said Colin Wilson, ESA project scientist for Mars Express.

“However, every bit of ice we find helps us build a better picture of where Mars’s water has flowed before, and where it can be found today.”

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Vish Gain is a journalist with Silicon Republic