A colossal slab of ice may be hiding at Mars鈥檚 equator. The composition of this deposit, called the Medusae Fossae Formation, has long been debated, but new data indicates that it contains enough water to cover the entire surface of Mars in an ocean 1.5 to 2.7 metres deep.
When the Mars Express orbiter first took radar measurements of Medusae Fossae in 2007, it wasn鈥檛 clear what the formation was made of. But new, more detailed data from the same orbiter shows that it is a huge deposit of water ice, similar to the planet鈥檚 polar ice caps.
The data revealed layers within the deposits, with major contrasts between the density and electrical conductivity of each layer. While previous research had suggested that the deposit could be made up of dust or volcanic ash, those materials don鈥檛 quite fit the new data. Instead, the layering closely resembles what researchers have seen in radar studies of the Martian polar ice caps.
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鈥淒ry material, no matter what it is, just doesn鈥檛 fit,鈥� says at the Smithsonian Institution in Washington DC. 鈥淲e just can鈥檛 come up with another material other than water ice that fits the electrical properties, that also has this layering that we鈥檙e finding.鈥� Watters led this new research as well as the observations in 2007.
This is the largest deposit of water ice found near Mars鈥檚 equator, which could potentially be useful for future Mars explorers. However, the ice appears to be buried under several hundred metres of dust and rocks, so it would be extremely difficult to access.
Nevertheless, its very existence is a significant clue to the climate history of Mars. For this huge chunk of ice to have formed, the area near the equator must have once been much colder than it is now, perhaps due to dramatic swings in the planet鈥檚 axis. 鈥淭he Martian climate could have gone through some periods of pretty radical changes,鈥� says Watters. 鈥淭hat would have set the stage for this deposit to have accumulated where it did.鈥�
Geophysical Research Letters
