- Image was captured during Martian spring, on May 21, by Mars Reconnaissance Orbiter’s HiRISE camera
- In Mars’ northern hemisphere, the snow and ice seen on the dunes is made of carbon dioxide – or, dry ice
- As it reacts to sun, the gas that escapes carries up the dark sand from below, creating ‘beautiful patterns’
As Martian winter gives way to spring, the snow-covered features on the red planet begin to change form, driven by an influx of sunlight.
It might sound familiar to the seasonal changes that take place here on Earth – but, in Mars’ northern hemisphere, the snow and ice speckling the landscape is made not of water, but carbon dioxide.
And, when this ‘dry ice’ is exposed to the sun, it creates remarkable patterns across the surface.
A stunning new image captured by NASA’s Mars Reconnaissance Orbiter has revealed a look at these features, showing how ice, sand, and gases react to form wave-like designs that ripple across the dunes.
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The image was captured on May 21, 2017 by the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera, according to NASA.
At this time, spring was underway in the Northern hemisphere.
‘Over the winter, snow and ice have inexorably covered the dunes,’ NASA explains. ‘Unlike on Earth, this snow and ice is carbon dioxide, better known to us as dry ice.
‘When the sun starts shining on it in the spring, the ice on the smooth surface of the dune cracks and escaping gas carries dark sand out from the dune below, often creating beautiful patterns.
‘On the rough surface between the dunes, frost is trapped behind small sheltered ridges.’
The Martian surface is covered in all sorts of remarkable features that have been brought to light by the spacecraft over recent years.
Earlier this summer, an infrared image from MRO showed a look at the worm-like fissures blanketing the floor of a mysterious crater on Mars.
SNOW ON MARS
As the atmosphere of Mars is cold and thin, water-ice clouds can form despite the limited amount of water vapour compared to Earth.
But until now, it had been thought that any snow precipitation that fell from these clouds did so as slowly settling particles, rather than in rapid storms.
A recent atmospheric model, however, revealed that the cooling of water-ice cloud particles during the cold Martian night can create unstable conditions within the cloud, triggering a descending plume of snow.
These turbulent storms, which can only form at night, act to vigorously mix the atmosphere and, in some places, deposit snow on the surface.
The image shows the spread of features known as ‘ejecta,’ or the material thrown across the surface after an impact.
In this view, the breathtaking colours indicate the presence of different rocks and minerals, including iron-rich minerals such as olivine and pyroxene.
While the blue features represent iron-rich areas, lighter colours such as yellow show where the rock has been altered, NASA explains.
The image was captured using MRO’s HiRISE instrument.
The experts say the features seen in this unnamed crater in Mars’ Mare Serpentis region are similar to those seen elsewhere, and can help to shed light on the subsurface materials kicked up after an impact.
It’s thought that the ejecta seen here comes from two unnamed craters.
‘These linear features indicate the flow direction of the ejecta from its unnamed host crater,’ according to NASA.
WHAT IS EJECTA?
Ejecta is the material cast across the surface after an impact.
This can include debris from the impact itself, as well as rock that was kicked up during the event.
The features also reveal insight on the ‘sometimes exotic subsurface.’
Therefore, if we follow them, we find that they emanate from the bottom of the two unnamed craters.
‘If the ejecta had originated from the top crater, then we would expect the linear features at the location of our picture to trend northwest to southeast.’
Molten rock once flowed along a crater rim in another region – Mars’ Tharsis volcanic province, creating stunning multi-level ‘lava’ falls.
A breathtaking image captured by NASA’s Mars Reconnaissance Orbiter revealed the incredible structures left behind, in a region reminiscent of Niagara Falls.
The photo shows a glimpse at the northern rim of a 19-mile-wide (30 kilometer) crater, with evidence that a lava flow once surrounded the region until it breached at four separate locations, to cascade down the walls.
The 3D image was captured by MRO’s Context Camera, according to NASA.
From this view, the western part of the Tharsis province can be seen.
The experts say the lava came in from the north-northeast around the crater rim – and when it got high enough, it breached the rim in four places.
Three of the falls, in the north-central region of the crater wall, can be seen in the image.
This is clear through their rougher appearance than the original features around, which are ‘smooth and knobby.’
‘These lava “falls” cascaded down the wall and terraces of the crater to produce a quasi-circular flow deposit,’ according to NASA.
‘It seems that the flow were insufficient to fill or even cover the pre-existing deposits of the crater floor.
‘This is evidenced by the darker-toned lavas that overlie the older, and possibly dustier, lighter-toned deposits on the crater floor.’
While Mars doesn’t have any water at the surface today, scientists say it had a watery past.
These particular features were carved by lava, which behaved like liquid water, but in other areas, NASA’s rovers have turned their sites to investigate evidence of ancient lakes.
NASA’s Opportunity rover is set to explore the edge of a crater just above Mars’ ‘Perseverance Valley,’ to uncover new clues on the processes that left rocks scattered across its floor.
A new color-enhanced image captured just before the Mars rover’s ‘walkabout’ survey kicked off shows a landscape that looks almost like a beach here on Earth, and scientists suspect water may have played a role in the rocks’ transportation.
The region may once have hosted a perched lake in the crater rim’s crest which acted as a spillway, the researchers say – or, they may have eroded in place by wind.
Opportunity has been investigating the areas on and around the western rim of the 14-mile-wide Endeavour Crater, which sits just above Perseverance Valley, since 2011.
Part of the crest at the top of the valley is marked by a broad notch, the researchers say.
And, just west of the feature, there are elongated patches of rocks lining a slightly depression.
The experts say this may have been a drainage channel billions of years ago.
‘We want to determine whether these are in-place rocks or transported rocks,’ Arvidson said.
MARS: A WET PLANET
Evidence of water on Mars dates back to the Mariner 9 mission, which arrived in 1971. It revealed clues of water erosion in river beds and canyons as well as weather fronts and fogs.
Viking orbiters that followed caused a revolution in our ideas about water on Mars by showing how floods broke through dams and carved deep valleys.
Mars is currently in the middle of an ice age, and before this study, scientists believed liquid water could not exist on its surface.
In June 2013, Curiosity found powerful evidence that water good enough to drink once flowed on Mars.
In September of the same year, the first scoop of soil analysed by Curiosity revealed that fine materials on the surface of the planet contain two per cent water by weight.
Last month, scientists provided the best estimates for water on Mars, claiming it once had more liquid H2) than the Arctic Ocean – and the planet kept these oceans for more than 1.5 billion years.
The findings suggest there was ample time and water for life on Mars to thrive, but over the last 3.7 billion years the red planet has lost 87 per cent of its water – leaving it barren and dry.
‘One possibility is that this site was the end of a catchment where a lake was perched against the outside of the crater rim.
‘A flood might have brought in the rocks, breached the rim and overflowed into the crater, carving the valley down the inner side of the rim.
‘Another possibility is that the area was fractured by the impact that created Endeavour Crater, then rock dikes filled the fractures, and we’re seeing effects of wind erosion on those filled fractures.’
The researchers say examining the rocks along what could be a channel could help to reveal more about the site’s history.
And, recently NASA’s Mars Reconnaissance Orbiter revealed another stunning look at the rugged terrain of the red planet, in a scene that could rival Britain’s beloved white cliffs.
The new view shows Mars’ breathtaking ‘white cliffs of rover,’ captured by the High Resolution Imaging Science Experiment (HiRISE) camera.
According to the space agency, the ocean-like surface at the bottom right side of the photo is actually an expanse of dunes, creating a striking contrast with the ‘shoreline’ beside it.
The image has been enhanced to better show the differences in the terrain, creating what appears to be a ‘cloud-covered cliff edge’ and foamy waves.
‘The reality is that the surface of Mars is much dryer than our imaginations might want to suggest,’ NASA explains.
‘This is only a tiny part of a much larger structure; an inverted crater – a crater that has been infilled by material that is more resistant to erosion than the rocks around it – surrounded by bluish basaltic dunes.
‘The edge of these elevated light-toned deposits are degraded, irregular and cliff-forming.’
Overall, the region known as Meridiani Planum is smooth, unlike much of the rest of Mars.
And, according to NASA, this also means it’s younger than other sites.
It’s known to contain hematite, and salt-bearing rocks known as sulfates.
The landscape has been compared to the White Cliffs of Dover – the famed cliffs of the British Isles that are now rapidly eroding in what’s thought to be a result of human activity.
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