Mars MRO HiRise: New evidence for ancient ocean

A vast ocean may have once covered a third of the Red Planet. 

Credit: ESA, C. Carreau

Did a vast ocean once cover Mars' northern plains?

The idea has been hotly debated among scientists for the past 20 years, ever since Viking Orbiter images revealed possible ancient shorelines near the pole.

Later findings even suggested that the primordial ocean, dubbed Oceanus Borealis, could have covered a third of the planet.

But even if the evidence has mounted steadily, fostering our hopes of finding signs of past life on the Red Planet, the case for an ancient Martian ocean remains unsettled.

Lorena Moscardelli

Now a new study by Lorena Moscardelli, a geologist at the University of Texas, Austin, puts forward yet another line of evidence.

Today, large fields of boulder-size rocks blanket parts of Mars' northern plains.

By pointing to analogue geological features on our Earth, Moscardelli suggests that the boulders were delivered to their current locations by catastrophic underwater landslides, bolstering evidence for an ancient Martian ocean.


The boulders were spotted by the HiRISE camera on the Mars Reconnaissance Orbiter a while ago.

So Moscardelli is not reporting their presence as something new, but rather a new interpretation of the processes behind their origin.

The paper was published this month in a journal of the Geological Society of America.

Terrestrial Analogy
In the past, geoscientists thought of ocean sediments as mostly fine-grained, floating in the water column and settling like a slow "rain" on the sea floor, Moscardelli explained. But we now know it's not the only possible scenario.

Boulder-size rocks in Arcadia Planitia, northern lowland of Mars (HiRISE ESP_019853_2410). 

Credit: NASA (Moscardelli 2014)

"We know that 'submarine landslides' can transport big boulders, sometimes as big as a house, for hundreds of kilometers into the deep-water of the Earth oceans," she said.

"Imagine a huge landslide affecting the entire state of Texas, but happening in the ocean."

In her new study, Moscardelli documents several sites where these events have occurred on Earth, such as the Pennsylvanian Jackfork Group of south-central Arkansas; the outcrops of the Guandacol Formation in the Pangazo Basin, Argentina; or in the Santos Basin, offshore Brazil.

She even shows that these underwater events can affect huge areas, as with a massive landslide that covered thousands of square kilometers in the Barents Sea, north of Russia, about a million years ago.

Some scientists have suggested that the boulders of Mars's northern plain could be the product of meteorite impacts. But to Moscardelli, that's not a fitting theory.

"That's possible for some of the boulders, especially those found close to craters," she says. "But how do you explain boulder fields that can cover thousands of square kilometers without any impact craters around?

"The submarine hypothesis provides a feasible alternative."

More information: Paper: www.geosociety.org/gsatoday/

NASA Curiosity Rover Finds New Evidence That Ancient Mars Was Habitable

The pale rock in the upper center of this image, about the size of a human forearm, includes a target called "Esperance," which was inspected by NASA's Mars Exploration Rover Opportunity.

This image is a composite of three exposures taken by Opportunity's panoramic camera during the 3,262nd Martian day, or sol, of the rover's work on Mars (March 28, 2013).

CREDIT: NASA/JPL-Caltech/Cornell/Arizona State Univ.

NASA's Mars rover Opportunity has made perhaps the biggest discovery of its nearly 10-year career, finding evidence that life may have been able to get a foothold on the Red Planet long ago.

The Opportunity rover spotted clay minerals in an ancient rock on the rim of Mars' Endeavour Crater, suggesting that benign, neutral-pH water once flowed through the area, scientists said.

"This is water you could drink," Opportunity principal investigator Steve Squyres of Cornell University told reporters today (June 7), explaining why the rock, dubbed "Esperance," stands out from other water-soaked stones the rover has studied.

"This is water that was probably much more favorable in its chemistry, in its pH, in its level of acidity, for things like prebiotic chemistry — the kind of chemistry that could lead to the origin of life," Squyres added.

Climate Change: new evidence of cooling properties of Criegee Intermediate atmospheric Molecule

Scientists have discovered further evidence for the existence of new molecules in the atmosphere that have the potential to off-set global warming by reacting with airborne pollutants.

Researchers from The University of Manchester, Bristol University, Southampton University and Sandia National Laboratories in California have detected the second simplest Criegee intermediate molecule – acetaldehyde oxide – and measured its reactivity.

Intermediates are molecules that are formed during a chemical reaction and react further to produce the final chemicals of the reaction. Criegee intermediates – carbonyl oxides – were first identifies by the team in January last year and shown to be powerful oxidisers, reacting with pollutants such as nitrogen dioxide and sulphur dioxide.

The authors, whose latest study is again published in the journal Science, believe Criegee intermediates have the potential to cool the planet by converting these pollutants into sulphate and nitrate compounds that will lead to aerosol and cloud formation.

Professor Carl Percival, who led the Manchester team in the University's School of Earth, Atmospheric and Environmental Sciences, said: "We have carried out the first ever studies on the second simplest Criegee intermediate and were able to show that it also reacts extremely quickly with sulphur dioxide to produce sulphates under experimental conditions.

"We can therefore say that the reaction of these intermediates with sulphur dioxide will have a significant impact on sulphuric acid production in the atmosphere if they follow the pattern established by these two studies.

The paper is titled "Direct Measurements of Conformer-Dependent Reactivity of the Criegee Intermediate CH3COOH," published in Science.

He continued: "One of the main questions from our first study was if this increased reactivity would be observed for other Criegee intermediates, so with these findings we now have additional evidence that Criegee intermediates are indeed powerful oxidisers of pollutants such as nitrogen dioxide and sulphur dioxide.

"What this study suggests is that the biosphere could have a significant impact on aerosol production and thus potentially climate cooling via the formation of Criegee intermediates. The next steps will be to carry out modelling studies to quantify the impact of Criegee intermediates on climate and to quantify the level of alkene present in various environments."

Rudolf Criegee

The formation of Criegee intermediates or biradicals was first postulated by the German chemist Rudolf Criegee in the 1950s but, despite their importance, it had not been possible to study the chemicals in the laboratory.

The detection of the molecules was made possible through a unique apparatus that uses light from a third-generation synchrotron facility at the Lawrence Berkeley National Laboratory.