Warmth and flowing water on early Mars, were episodic

Although the surface is now cold and desiccated, in early Mars history water formed an open-basin lake, filling the crater, forming a delta, and breaching the lower rim as water flowed to lower elevations (blue). 

New research suggests that warmer temperatures and water flow on ancient Mars were likely related to periodic volcanism early in the planet's history 

Credit: NASA /Mars Reconnaissance Orbiter Rendering by James Dickson, Brown University

Ample evidence of ancient rivers, streams, and lakes make it clear that Mars was at some point warm enough for liquid water to flow on its surface.

While that may conjure up images of a tropical Martian paradise, new research published today in Nature Geoscience throws a bit of cold water on that notion.

The study, by scientists from Brown University and Israel's Weizmann Institute of Science, suggests that warmth and water flow on ancient Mars were probably episodic, related to brief periods of volcanic activity that spewed tons of greenhouse-inducing sulfur dioxide gas into the atmosphere.

The work, which combines the effect of volcanism with the latest climate models of early Mars, suggests that periods of temperatures warm enough for water to flow likely lasted for only tens or hundreds of years at a time.

With all that's been learned about Mars in recent years, the mystery of the planet's ancient water has deepened in some respects.

The latest generation of climate models for early Mars suggests an atmosphere too thin to heat the planet enough for water to flow.

The sun was also much dimmer billions of years ago than it is today, further complicating the picture of a warmer early Mars.

"These new climate models that predict a cold and ice-covered world have been difficult to reconcile with the abundant evidence that water flowed across the surface to form streams and lakes," said James W. Head, professor of earth, environmental and planetary sciences at Brown University and co-author of the new paper with Weizmann's Itay Halevy.

Itay Halevy

"This new analysis provides a mechanism for episodic periods of heating and melting of snow and ice that could have each lasted decades to centuries."

Halevy and Head explored the idea that heating may have been linked to periodic volcanism.

Many of the geological features that suggest water flow date to around 3.7 billion years ago, a time when massive volcanoes are thought to have been active and huge lava outpourings occurred.

On Earth, however, widespread volcanism often leads to cooling rather than warming. Sulphuric acid particles and thick ash reflect the sun's rays, and that can lower temperatures, but Head and Halevy thought the effects of sulphur in Mars' dusty atmosphere might have been different.

To find out, the researchers created a model of how sulfuric acid might react with the widespread dust in the Martian atmosphere.

The work suggests that those sulphuric acid particles would have glommed onto dust particles, which would reduce their ability to reflect the sun's rays.

Meanwhile sulphur dioxide gas would produce a modest greenhouse effect, just enough to warm the Martian equatorial region so that water could flow.

Head has been doing fieldwork for years in Antarctica and thinks the climate on early Mars may have been very similar to that of the cold, desert-like McMurdo Dry Valleys.

"The average yearly temperature in the Antarctic Dry Valleys is way below freezing, but peak summer daytime temperatures can exceed the melting point of water, forming transient streams, which then refreeze," Head said.

"In a similar manner, we find that volcanism can bring the temperature on early Mars above the melting point for decades to centuries, causing episodic periods of stream and lake formation."

But as that early active volcanism on Mars ceased, so did the possibility of warmer temperatures and flowing water.

Head said the research may offer new clues about where the fossilized remnants of life might be found on Mars, if it ever existed.

"Life in Antarctica, in the form of algal mats, is very resistant to extremely cold and dry conditions and simply waits for the episodic infusion of water to 'bloom' and develop," he said.

"Thus, the ancient and currently dry and barren river and lake floors on Mars may harbor the remnants of similar primitive life, if it ever occurred on Mars."

More information: Nature Geoscience, dx.doi.org/10.1038/ngeo2293

NASA Mars HiRise: Study of Aeolis Dorsa and Halcyon times

This NASA image obtained by the Mars HiRISE camera March 13, 2014 shows a sand dune field in a Southern highlands crater on Mars

Cold and dry today, Mars was previously warm and wet but possibly only at intervals, a study published on Sunday suggests.

Scientists have long puzzled over what happened to the water, the precious stuff of life, on the Red Planet.

Unmanned spacecraft have sent home tantalising images of gouged canyons, valleys and sedimentary deltas, while landers have found hydrous rocks, all suggesting Mars at one time hosted hundreds of kilometres (miles) of rivers and lakes.

Today, though, Mars is too cold and the pressure of its carbon-dioxide atmosphere way too low for liquid H2O to exist. If you tried to pour water on its surface, it would simultaneously freeze and vapourise.

So when did Mars host liquid water? And what happened to it?
In a study published in the journal Nature Geoscience, planetary geologist Edwin Kite of the California Institute of Technology takes a new stab at the riddle.

Edwin Kite

Kite and his team measured craters, left on the Martian surface by asteroid collisions, to gain an idea of its past atmospheric pressure.

The principle behind their calculation is this: the thicker the atmosphere, the bigger the space rock has to be to survive the friction of contact with it.

Conversely, a thinner atmosphere means that smaller rocks are able to survive the descent and whack the surface.

Aeolis Dorsa

Kite's team looked at 319 craters in Aeolis Dorsa, a 3.6-billion-year-old region that shows evidence of past rivers to get an indication.

Mystery of flowing water They calculated that these craters were formed when Mars had atmospheric pressure of up to 0.9 bar.

This pressure is 150 times greater than that of today and intriguingly close to that of the water-rich Planet Earth at sea level.

The bad news, though, is that Mars is far more distant from the Sun than Earth and at that far-off time, our star was much less bright than now.

As a result, Mars would have required pressures of at least five bar for its surface to keep above the freezing point of water. It seems to have lacked a long-lasting thick atmosphere during its river period.

"If Mars did not have a stable multi-bar atmosphere at the time that the rivers were flowing—as suggested by our results—then a warm and wet CO2/H2O greenhouse is ruled out, and long-term average temperatures were most likely below freezing," said the study.

Sanjoy Som

This throws up other possible explanations for the water, said Sanjoy Som of NASA Ames Research Center in a commentary published in the same journal.

One is that the water was high in acidity and salt content, giving it a lower freezing point and enabling it survive as a liquid in lower air pressure.

Another is that greenhouse gases from volcanic eruptions helped Mars, for a while, to have a denser atmosphere that enabled the water to flow.

Another possibility is "transient intervals" of denser atmosphere caused by the planet's tilt, said Som.

Like a child's top that is slightly off centre, Mars tilts slowly around its axis of spin.

It takes 120,000 years to complete one axial revolution, a timescale that leads to major changes in the amount of sunlight reaching its poles, whose water either froze to form ice-sheets or warmed to "reinflate" the atmosphere and form rivers that flowed at kinder times.

More information: Nature paper: Low palaeopressure of the martian atmosphere estimated from the size distribution of ancient craters, www.nature.com

NASA LRO: Wet or Dry Moon

The Moon's status as a "dry" rock in space has long been questioned. Competing theories abound as to the source of the H20 in the lunar soil, including delivery of water to the Moon by comets.

This week, Tartèse et al announced in Geology that new analyses of lunar soil samples demonstrates that basalts from the Moon's mantle contain hydrogen from water indigenous to Earth.

According to the authors, their work is "challenging the paradigm of a "dry" Moon, and arguing that some portions of the lunar interior are as wet as some regions of the Earth's mantle."


This video from NASA Goddard shows how NASA’s Lunar Reconnaissance Orbiter (LRO) is helping scientists understand where water is likely to exist on the south pole of the Moon. 

Credit: NASA Goddard on YouTube

Since the 1960's, scientists have suspected that frozen water could survive in cold, dark craters at the Moon's poles.

While previous lunar missions have detected hints of water on the Moon, new data from the Lunar Reconnaissance Orbiter (LRO) pinpoints areas near the south pole where water is likely to exist.

The key to this discovery is hydrogen, the main ingredient in water: LRO uses its Lunar Exploration Neutron Detector (LEND), to measure how much hydrogen is trapped within the lunar soil.

By combining years of LEND data, scientists see mounting evidence of hydrogen-rich areas near the Moon's south pole, strongly suggesting the presence of frozen water.

More information: Romain Tartèse, Mahesh Anand, Francis M. McCubbin, Stephen M. Elardo, Charles K. Shearer, and Ian A. Franchi. "Apatites in lunar KREEP basalts: The missing link to understanding the H isotope systematics of the Moon." Geology, G35288.1, first published on February 25, 2014, DOI: 10.1130/G35288.1

NASA MAVEN: 'Tour' ancient, wet Mars in YouTube video

NASA's Goddard Space Flight Center has release a YouTube video it says shows how Mars may have looked 4 billion years ago.

When the Red Planet was young, it appears to have had a thick atmosphere that was warm enough to support oceans of liquid water -- a critical ingredient for life -- and the YouTube video shows how the planet could have appeared at the time, the space agency said Wednesday.

Beginning with a flyover of a martian lake, rapidly moving clouds suggest the passage of time and the shift from a warm and wet to a cold and dry climate.

As millions of years fly by the lakes dry up, while the atmosphere gradually transitions from Earth-like blue skies to the dusty pink and tan hues seen on Mars today.

NASA's YouTube "tour" of Mars comes as it prepares to launch its MAVEN spacecraft that will study the planet's atmosphere.

The launch is set for Nov. 18 from Florida's Cape Canaveral Air Force Station.

A Concept of Wet Mars

A conception of an ancient and/or future Mars, flush with oceans, clouds and life. 

Credit: Kevin Gill 

Over the years, scientists have found evidence revealing that an ocean may have covered parts of the Red Planet billions of years ago.

Others suggest that a future terra-formed Mars could be lush with oceans and vegetation.

 In either scenario, what would Mars look like as a planet alive with water and life?

By combining data from several sources — along with a bit of creative license — software engineer Kevin Gill has created some gorgeous images showing concepts of what a “living Mars” might look like from orbit, turning the Red Planet into its own version of the Blue Marble.