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Rover unearths evidence of flooding on Mars in distant past

The six-wheeled robot is looking for evidence of water or ice in a large plain in the northern hemisphere named Utopia Planitia.

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Images reveal shallow impact craters and other geologic formations on the Red Planet's complex sub-surface. (Photo via SWNS)

By Mark Waghorn via SWNS

Ground-penetrating radar from China's Zhurong rover has unearthed evidence of flooding on Mars in the distant past.

Images also reveal shallow impact craters and other geologic formations in the top five 16.4 feet of the Red Planet's complex sub-surface.

The six-wheeled robot is looking for evidence of water or ice in a large plain in the northern hemisphere named Utopia Planitia.

It has also been capturing pictures of rocks, sand dunes and a selfie - taken by a wireless camera.

Burial by wind-blown sediment are believed to have protected the craters from erosion. One had its rim exposed at the surface.

Lead author Professor Yi Xu, of Macau University of Science and Technology, explained: "We found a lot of dunes on the surface at the landing site.

"So maybe this crater was quickly buried by the sand and then this cover reduced space weathering, so we can see the full shape of these crater walls."

Zhurong landed almost two years ago near the boundary between the lowlands and highlands.

It has since travelled more than a mile south - sending electromagentic pulses through the soil, or regolith.

Analyzing the time delay of those reflected back by any materials they pass over give information on what lies beneath.

Two radar frequencies are used - the lower reaching around 262.5 feet deep.

The higher shows more detail but only reaches up to 16 feet down.

(Photo via SWNS)

It is hoped imaging will shed light on Mars' geologic history, previous climate conditions and any water or ice now or in the past.

The region was chosen because it's close to suspected ancient shorelines and other interesting features where there may have been rivers or lakes.

The study, published in the journal Geology, identified buried impact craters from several curving and dipping underground structures.

Other sloping features have less certain origins. There was no evidence of water or ice near the surface.

Xu said: "Radar images of the deeper structures revealed layers of sediment left by episodes of flooding and deposition in the past, but also found no evidence of water in the present day.

"This does not rule out the possibility of water deeper than the eighty meters imaged with the radar."

The researchers also contrast the data from Mars with ground-penetrating radar previously collected from the moon.

It shows a much different shallow subsurface structure.

The shallow Martian surface contains several distinct features that show up in the radar

(Photo via SWNS)

The top 10 meters of the moon has fine layers, but no evidence of other structures like impact crater walls - despite also being subjected to meteorite bombardment.

The walls of impact craters are, however, observed at greater depths on the moon, buried beneath the ten metre thick layer of fine debris.

Xu said: "The difference may be in the atmosphere. While Mars' atmosphere is a meager one percent of the volume of Earth's, the moon has virtually no atmosphere.

"With essentially no atmospheric protection, the moon's surface is bombarded by more of the smallest micrometeorites that rework the surface, eroding smaller-scale features and leaving behind fine layers of ejecta.

"By contrast, the surface of Mars is not being subjected to as many micrometeorite impacts because these smaller objects burn up in the atmosphere."

In 2016 a large body of underground ice was identified in the area by NASA's Mars Reconnaissance Orbiter.

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