An Opportunity for life: Finding Mars' most liveable mud

Jan 24, 2014 by Paulo De Souza, The Conversation
Opportunity trundles along looking for more evidence of water – and life – on Mars. Credit: NASA

Coinciding with ten years of the NASA Mars Exploration Rover Project, research published today in Science has found some of the oldest evidence of past water on Mars – and confirmed it was ideal to nurture life.

Found in ancient mudstones at Mars' Endeavour Crater, the geochemical data collected by the Opportunity Rover shows that was almost fresh. It would have been, almost four billion years ago, the most liveable mud on Mars.

Opportunity sampled the Matijevic formation – a grouping of fine-grained, layered rocks enriched with clay minerals – and analyses showed they were the oldest Martian rocks, and had the earliest evidence of water activity, the rover has encountered so far.

Back in 2004, Opportunity discovered rich deposits on hematite, jarosite and round concretions we dubbed "blueberries". That was definitive proof that an ocean flowed on Mars.

However, scientists around the world were sceptical about the suitability for life as that water was probably too acidic. Just as you wouldn't quench your thirst with a glass of vinegar, this water would not make the kind of mud microbes would be able to live in.

But our results indicate that microbes would have found in that place a delight to live in – not too salty, not too acidic, but just right.

Now we just need to see if there were any microbes there, by searching for any fossils that might hint that Mars was once inhabited and not just habitable. The search, and the fascination, goes on.

Centuries of wondering

As a long-term member of the science team guiding research on Mars, I'd like to reflect on what we're looking for and why it's worthwhile to keep exploring.

Start by looking at the night sky. Even though we can see just a part of it, the universe has more stars and planets than you could possibly imagine. Yet just a few hundred years ago, we thought we on Earth were at the centre of the universe, putting us in a very special place.

The science done by our first astronomers revealed that, in fact, we were turning around the sun. Later we discovered our sun is just another star, one of many in the universe.

False-colour image of Matijevic formation rocks. They are 3.7 billion years old and contain evidence that fresh water once flowed over them. Credit: Science/AAAS

The first confirmed accounts for another planet beyond our solar system was reported in 1988 by Canadian astronomers Campbell, Walker and Yang. The natural questions we now face are: is there life somewhere else in the universe? Or are we alone?

In the thousands of years since the Egyptians and Babylonians first knew of its existence, the red planet has been an object of study and fascination. More recent perspectives on Mars are also interesting to revisit.

In 1877, Italian astronomer Giovanni Schiaparelli saw "continents", "seas" and "channels" on Mars through his telescope.

The War of the Worlds novel by H G Wells captured public imagination and its famous adaptation by Orson Welles for radio broadcast in 1938 fooled audiences into thinking Martians were invading us.

More recently still, with the advancement of science, we've been in a position to get a more accurate picture of our nearest neighbour. The world of sensors, where my expertise lies, has leaped ahead so we can send compact sensors on spacecraft that gather a wealth of information.

With all this combined international exploration effort, we've sent many spacecraft to Mars to study large areas from the air and in minute detail on the ground.

Credit: NASA

The list of spacecraft reads like a roll-call at school:

All these landers and rovers on Mars' surface are being supported by a number of orbiters like Mars Odyssey, Mars Reconnaissance, Mars Global Surveyor and the European Space Agency's Mars Express.

We also have an Indian mission Mangalyaan on the way to Mars today, a number of missions being planned for the future like the rover on 2020, Chinese attempts to get there as well as the lottery for a one-way ticket to the .

Our reason for living

Simulated image of Opportunity on ‘Burns Cliff’, Mars. Credit: NASA

All this exploration was fuelled by the 1996 analysis of the meteorite ALH84001 in Antarctica. This meteorite came from Mars, has carbonate in its chemistry (carbonate needs water to be formed) and has a number of structures that resemble fossilised bacteria.

Since then the traffic on Mars has never been so intense.

But what are we looking for so intensively on Mars? The answer is everywhere on a full-of-life Earth: water.

Even though some landscape features observed by Mars orbiters provide evidence that liquid water might have flowed on the surface of Mars long ago, surface studies like ours look for direct evidence for mineral deposits created by an interaction with water and rock. The gadgetry on the Mars Rovers is designed to carry out these sophisticated geochemical analyses.

Life, as we know it, depends on water to be formed, sustained and to evolve. It does not mean, however, that life somewhere else in the universe might not depend on another substance. It is much easier to look for something we know so well.

Explore further: Mars rover photographs featured at US museum (Update)

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User comments : 13

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Dichotomy
not rated yet Jan 24, 2014
The more important question to me atleast is "how did Mars go from being a planet with a much more abundant atmosphere and flowing water to the desolate planet it is now?"
Whydening Gyre
not rated yet Jan 24, 2014
The more important question to me at least is "how did Mars go from being a planet with a much more abundant atmosphere and flowing water to the desolate planet it is now?"

Here's a postulate that might fit - Humans used to live there and Venus...
roblabs
1 / 5 (3) Jan 24, 2014
GASP! Are you saying that....Earth is next!?
The Shootist
not rated yet Jan 24, 2014
How can Opportunity find "Mars' most liveable mud", when planetary landers are intentionally not placed where life, heat, or liquid water, is most likely to be found?

Stupid, puny humans.
Torbjorn_Larsson_OM
5 / 5 (1) Jan 24, 2014
For a fascinating update on astrobiology, I recommend "Many Paths to the Origin of Life" (Gollihar et al, Science, 17 Jan 2014). The scientific mainstay of the RNA World theory, now competing with the promising Alkaline Hydrothermal theory, would by itself need a prebiotic ribose production. And so far the best environment for that would be oxidized, dry minerals - Mars rather than early neutral, wet Earth.

But the author's conclude that local production would be most likely anyway: "The demonstration of ribose formation under some prebiotic conditions does not necessarily mean that we have to punt to Mars, but rather that a problem once thought intractable is now yielding to broader scientific inquiry." (Viz, the AHT metabolism and RNA now known to allow heterogenity in chemical bonds so a broader set of prebiotic pathways.)
Torbjorn_Larsson_OM
5 / 5 (2) Jan 24, 2014
@The Shootist: The landers have a very constrained landing environment, it has to be at least 1 km below the datum for the atmospheric braking to work. (A famous too thin, too thick atmosphere problem.) That restricts the landers to the norther lowlands.

But that doesn't matter. They are discussing geological habitability, note the absence of present tense. And by the 3 large rover's results the northern lowlands used to be an ocean (see above), or at least had fresh water flows later (Curiosity). So that is what they are discussing, a "liveable mud" ~ 4 Ga bp.
Whydening Gyre
not rated yet Jan 24, 2014
GASP! Are you saying that....Earth is next!?

So far kind looks that way, don't it...
There's a term for it in biology - I forget the exact term at the moment...
Anyway, we as "proteasomes" seem to be missing the proper protein that guides in how to clean up after ourselves...
The Shootist
5 / 5 (2) Jan 24, 2014
The more important question to me atleast is "how did Mars go from being a planet with a much more abundant atmosphere and flowing water to the desolate planet it is now?"


Time period 4Gy.

Late Heavy Bombardment/Lunar cataclysm occurred: 4.0-3.8Gy. Impacts blew the majority of the atmosphere away and stopped the Martian dynamo. Solar winds took care of the rest.

Probable answer.
GSwift7
not rated yet Jan 24, 2014
Torbjorn:

And so far the best environment for that would be oxidized, dry minerals


Unfortunately, the article you linked to is paywalled.

I thought oxygen was bad. Are they suggesting the bonded oxygen as a safe way for the prebiotics to pick up some oxygen without being oxidized? Also, if it's dry, then where is the hydrogen coming from?

Also, how does this mesh with the geothermal vent genesis?

One more: Are we talking about micro or macro habitats here? I'm not really understanding if you're suggesting cracks in rocks or large, open areas.

I really don't see how probability would favor any kind of micro-climate situation.
GSwift7
not rated yet Jan 24, 2014
continued:

I know this is pure armchair stuff, since I suck at biology and chemistry, but I have one more thing to inquire about.

I guess genesis could start at a point source and bloom out from there like an outbreak, but it just seems so unlikely it would work out statistically.

Isn't a widespread environment, with many chances for genesis accross a range of similar conditions more logical? I think it is likely that there would have been any number of false starts before it actually started to survive climatic cycles.

I guess that in itself might favor microclimates, like cracks in underground rocks, since they would be more stable, but it still seems too isolated. Furthermore, if that were the case, then why don't we see it happening in present day micro-environs of that type? Could we see it, if it is happening? Do we even have anything that could detect it?
GSwift7
not rated yet Jan 24, 2014
Damn, I hate feeling like a wide-eyed child in a candy store, but I really am curious about the current gold rush in this field. Sorry for all the questions that probably don't make enough sense to answer, but that's how it goes when you get interested in something that's way out of your (my) area of education.
Danie
not rated yet Jan 25, 2014
The description on the first picture would suggest it to be a actual picture, but that would leave the question, who took it ?

Otherwise, very interesting article and comments here. As far as the loss of atmosphere, oxygen, water is concerned, there is a good theory backed by some evidence, that Mars was hit by a massive body, which stopped its core from rotating. Which is also how Olympus Mons got so big. With no plate movement all magma was released in one location over many years.
RealScience
not rated yet Jan 26, 2014
I guess that in itself might favor microclimates, like cracks in underground rocks, since they would be more stable, but it still seems too isolated. Furthermore, if that were the case, then why don't we see it happening in present day micro-environs of that type? Could we see it, if it is happening? Do we even have anything that could detect it?

The evidence is that acidity gradients (pH) made amino acids and nucleic acids energetically favorable, so they accumulated into a 'soup'. That just barely starts happening today around 'white smoker' alkaline undersea vents, but current life sees such molecules as food and consumes them before they accumulate.
Basically once life gets going it quickly evolves to be so efficient at scavenging energy-supplying molecules that new life never gets a chance to evolve in that ecosystem.