Martian water vs. the volcanoes

July 27, 2011 By Larry O'Hanlon, Inside Science News Service
This image shows Dao, Niger, and Harmakhis Valles emerging from the flank of the Hecates volcano. The association between the volcano and the outflow channel may imply a hydrothermal origin for the channel. Credit: NASA

For decades NASA has been "following the water" on Mars with hopes of finding signs of alien life there; or at least signs that future colonists won't die of thirst. Now a Texas geologist has dared to revive an old, almost heretical idea -- backed up with all the latest data -- that the Red Planet has been bone dry for billions of years.

Mars' spectacular grand canyons were not carved by catastrophic floods, says Texas Tech's David Leverington, but by slippery, low-viscosity lavas. This hypothesis fits happily within a wider geological framework of and compares well with similar channel-like features on the moon and Venus, he said.  

If Leverington is right, the odds of life on Mars plummet to near zero. But that's a big "if." Many veteran Mars researchers are far from buying the lava story and are still pretty certain that water played a significant part in sculpting the compelling 1,200-mile long, 60-mile wide outflow channels that stunned the world when they were first imaged by Viking spacecraft in the late 1970s.

Holes In The Water

Leverington's approach, as explained in his soon-to-be published paper in the Sept. 2011 issue of the journal Geomorphology, is to take apart some of the major assumptions of the "aqueous" models used to explain how water could have scoured out the outflow channels.

First there is the matter of the sources of all the water. Some Mars water advocates have calculated that the volume of water would, in some cases, need to exceed those of the greatest rivers on Earth, perhaps being more on par with something like the Atlantic Ocean's Gulf Stream current.

"The question is: How do you get that volume of water?" said Leverington. "How do you move it quickly enough to rush out at a rate to carve channels like these?"

There are no huge empty lake beds at the heads of the outflow channels. So researchers have hypothesized vast permafrost-sealed aquifers in extremely porous, permeable ground that was suddenly breached by meteor impacts, faulting or upwards movements of hot magma in the Martian crust. In order for that scenario to work other researchers have calculated that the permeability of the Martian crust would need to be 1-10 million times greater than seems evident or likely, he said.

Another puzzle is the location of the starting points of the outflow channels. They tend to start up on the flanks of volcanoes. That doesn't fit the water hypothesis, said Leverington, because outflows of such huge volumes of water would be more likely from breaches at lower elevations so that there is plenty of "head" uphill of the breach pushing the water out below.  

One more thorn in the side of the aqueous hypothesis, Leverington said, is the mineralogy of Mars. There are few sediments and minerals that are consistent with a wet planet. Except for some clays found in rocks from the very earliest period in Mars history, which are far older than the outflow channels, the minerals found on Mars are not the kind that would survive contact with water and would reform as different minerals if the planet cycled through wet and dry periods. In other words, these minerals would not exist if water was common anytime in the near geologic past.  

"I would argue that all of these diverse types of data point firmly at volcanic mechanisms," said Leverington.

Conflicting Views

But not so fast, says highly respected veteran Mars researcher Victor Baker, of the University of Arizona's Lunar and Planetary Laboratory in Tucson, Ariz. Just because there are some problems with the water hypothesis is no reason to throw it out entirely, he said. What's more, you have to be careful not only when you compare Martian features to Earth's, but also to other planets.

"He's reasoning on the features of Moon and Venus when we don't know the causes of those features either," said Baker.
So while there might be similarities, it's not at all clear that erosive, low viscosity lavas are the common cause. "It's very obvious that immense flows of water and lava have been involved," said Baker.
Baker also warns against falling wholeheartedly for the lava just because it seems simpler. "To say something is better because it's simpler is how physicists think," said Baker. That reasoning is less successful in the more complicated world of geology. "Simplicity is a human artifact," he said.

This might sound rather philosophical, but it comes from Baker's decades of watching and participating in many Mars water controversies.

"Mars is great because it has a character of familiarity and strangeness," said Baker.

That, at least, is something on which he and Leverington agree.

"Previously I had a very terrestrial view of the Martian surface," said Leverington. On Earth, water is the great molder of landscapes, after all. But after staring at enough images of strange channels on the and Venus, his perspective changed. "Now I try to get away from the provincialism that we have as inhabitants of this world."

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4.5 / 5 (2) Jul 27, 2011
I'd like to point out that the porousness of the rock is assuming that there is little deliniation. If there is a lava cavern with a wall that becomes breached like a dam, the porousness of the rock is inconsequential. Albeit, that explanation still supports the lava hypothesis.

At some point we need to send a dozen mini drilling derricks down there and get some better geological data, settle bets, and resolve the arguments.

Of course, as space exploration goes, for every question answered, there are ten more that come up.
5 / 5 (2) Jul 27, 2011
If lava was the cause, wouldn't great beds, much like the moon's darker lava fields, be evident and possible to detect by spectrography?
not rated yet Jul 27, 2011
When I look at images of Mars I see signs of vast lava tubes, not flowing rivers of water. I think Mars was once quite volcanically active, but most of the action was going on underground. Today, we putter around the surface in our dune buggies -- so close but yet so far. In less than twenty years, the Chinese will arrive, and they will dig. Exploring the vast caverns of Mars will be one of the greatest adventures in our solar system. But don't count on seeing it. The Chinese will keep their successes (and failures) secret. And I gather we won't be going anytime soon.
1 / 5 (1) Jul 27, 2011
It may be that those canyons were not carved out by water but that says nothing about the presence of surface water and life in early Mars history. The evidence that has been released by NASA indicates that the atmosphere is nearly saturated with water. This is only possible if water (surface) and the atmosphere are in equilibrium. In addition the Phoenix program has shown water ice just below the surface. In addition there are photo's of the rovers driving through what clearly is wet soil.
The statement: For decades NASA has been "following the water" on Mars with hopes of finding signs of alien life there; or at least signs that future colonists won't die of thirst. ..." is classic NASA obfuscation!! NASA has specifically NOT looked (openly) for life on Mars since the Viking missions in the late '70's.

A half truth is still a lie.
not rated yet Jul 27, 2011
If lava was the cause, wouldn't great beds, much like the moon's darker lava fields, be evident and possible to detect by spectrography?

Mars Experiences weathering. The moon doesn't. Also, the water can change the chemistry of basalt.

Also, the far side of the moon does not have the same kind of basalt beds as the near side. Those are specifically caused by a large impact. While mars did at one time experience a similar impact event, it was very long ago, and before the end of mars' wet epoch, therefore much more subject to said weathering.

And mars does not necessarily have the same initial chemical makeup as the earth/moon.
4.5 / 5 (2) Jul 27, 2011
odds of life on Mars plummet to near zero

This is always a simplified statement from "odds of life we are familiar with", Today we find life under conditions that 100 years ago we would have said was impossible.
not rated yet Jul 28, 2011
NASA has specifically NOT looked (openly) for life on Mars since the Viking missions in the late '70's.

And even that only try yielded a strong positive result - the LR experiment. The other experiments most possibly failed to detect organics due to the heating of the sample and peroxides which we now know to exist on Mars (Phoenix). The LR experiment did not heat the samples to temperatures where peroxide starts to violently oxidizes and detected per pre mission constraints biologic activity in martian soil!

Regarding this topic: many martian channels originate in areas with no visible remnants of major volcanic activity (eg Mawrth Vallis). For me this hints to long term periods with heavy rain and snowfall on Mars. Remember even today there is snowfall on Mars (Phoenix).
not rated yet Jul 28, 2011
And mars does not necessarily have the same initial chemical makeup as the earth/moon.

All very true, but geology is one of those areas where things: are. Re-melted rock has a very obvious signature that can't be hidden even 3 billion years later except by a few feet of blown sand.

There was an article a bunch of weeks ago showing a recent (Within past 20 years I think?) channel made on the side of an escarpment, but I can't seem to locate it. I wish I could. It pretty much confirmed the process is still active even now.

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