Meteorites reveal warm water existed on Mars

Nov 15, 2012
This is an Electron Microscope image of the Lafayette meteorite (NHM sample BM 1959, 755). It shows the hydrous vein with carbonate and clay deposited by water at up to 150 oC on Mars due to an ancient impact. The field of view is 50 microns. Credit: University of Leicester

New research by the University of Leicester and The Open University into evidence of water on Mars, sufficiently warm enough to support life, has been published this week in the journal Earth and Planetary Science Letters.

The study determined that on the ranged from 50°C to 150°C. Microbes on Earth can live in similar waters, for example in the volcanic thermal springs at Yellowstone Park, the scientists behind the research point out.

The research is based on detailed scrutiny of meteorites on Earth using powerful microscopes in the University of Leicester Department of Physics and Astronomy. This was followed-up by computer modeling work at The Open University.

Dr John Bridges, Reader in Planetary Science in the University of Leicester Space Research Centre and Lead Author, said: "Rovers on Mars – the Mars Exploration rovers Spirit and Opportunity, and the Laboratory rover Curiosity – are studying rocks to find out about the of the Red Planet. Some of the most interesting questions are what we can find out about water, how much there was and what temperature it might have had.

"While the orbiters and rovers are studying the minerals on Mars, we also have meteorites from Mars here on Earth. They come in three different groups, the shergottites, the nakhlites and the chassignites. Of most interest for the question of water on Mars are the nakhlites, because this group of Martian meteorites contains small veins, which are filled with minerals formed by the action of water near the surface of Mars."

Dr. Bridges and his group studied those alteration minerals in great detail. Altogether eight nakhlite are known, and all have small but significant differences between them and in their alteration minerals.

Lafayette is one of them; and the most complete succession of newly formed minerals can be found in its veins (see figure). Careful investigations of the minerals with an electron microscope and a transmission electron microscope have revealed that the first newly formed mineral to grow along the walls of the vein was iron carbonate. The carbonate would have been formed by CO2-rich water around 150°C. When the water cooled to 50°C, it would have formed the clay minerals, which were then followed by an amorphous phase that has the same composition as the clay.

Microbes use the reactions during mineral formation to gain energy and elements essential for their survival.

Dr Bridges added: "The mineralogical details we see tell us that there had been high carbon dioxide pressure in the veins to form the carbonates. Conditions then changed to less carbon dioxide in the fluid and clay minerals formed. We have a good understanding of the conditions minerals form in but to get to the details, chemical models are needed."

Dr Susanne Schwenzer, Postdoctoral Research Associate in the Department of Physical Sciences at The Open University who previously studied Martian meteorite compositions, said: "Until John's study was finished, I used the findings from orbiters around Mars, and modelled each of the new minerals individually. Those orbiters have found clays on the surface of Mars, but the spatial resolution is very different from the detailed study achieved in the nakhlites. Before we had the detailed study of the nakhlite meteorites, we did not know that carbonates are forming first, followed by the clays. Therefore I was very excited to see the details of the new mineralogical study."

By combining data from both universities, researchers were able to predict water conditions on Mars. Initially, the water was around 150°C and contained a lot of CO2, forming the carbonates, then cooled to about 50°C, thus forming the clays.

"The driving force heating the might have been an impact into the Martian surface." Dr. Bridges explains. "And you only have to look at a map of Mars to see how numerous those are on the Martian surface," Dr. Schwenzer adds.

Explore further: Easter morning delivery for space station

More information: Bridges J.C. and Schwenzer S.P. The nakhlite hydrothermal brine on Mars. Earth and Planetary Science Letters 359 (2012) 117.

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Modernmystic
1 / 5 (1) Nov 15, 2012
Interesting. If we do not find any indicators that life once existed on Mars given that it could have, and given how quickly it seems to have originated on Earth, it would pain a much more dim picture of finding it elsewhere outside our solar system.
Maggnus
3 / 5 (2) Nov 15, 2012
given how quickly it seems to have originated on Earth, it would pain a much more dim picture of finding it elsewhere outside our solar system.


I don't know why you would say that. While finding life did or does exist on Mars would greatly increase the possibility that life exists in great abundance in places besides earth, the lack of it being there has pretty well no impact on our chances of finding life elsewhere. It's a big universe out there!
GSwift7
2.3 / 5 (3) Nov 15, 2012
Interesting. If we do not find any indicators that life once existed on Mars given that it could have, and given how quickly it seems to have originated on Earth, it would paint a much more dim picture of finding it elsewhere outside our solar system


Maybe, maybe not. That depends on why Mars didn't get life, if that turns out to be the case. If the reason is because of X and X is common on other planets, then that's bad. On the other hand, if X isn't common on other planets, then it doesn't tell us much.

Unfortunately, this is a case where the null hypothesis must be disproven rather than the other way around. Until we actually prove that life formed somewhere else independently from Earth, we can't assume that there's life anywhere else.

Even if we find signs of life on Mars, it doesn't mean much in terms of life elsewhere unless we can show that it was seperate from life on Earth as opposed to coming from a common source.
Caliban
5 / 5 (3) Nov 15, 2012
A reliance upon Impact Events as the source of heat to create these minerals on any large enough scale to give rise to life is probably mistaken, as heat produced in such fashion would be both intermittent and (relatively)short-lived.

Such events may very well be responsible for at least some of the alteration-product minerals found in this Martian meteoritic material, as well as on the Martian surface --but, geothermal heating and atmospheric/surface heating would be the most likely source to produce the conditions required for the beginning of any Life on Mars.
GSwift7
3.4 / 5 (5) Nov 15, 2012
A reliance upon Impact Events as the source of heat to create these minerals on any large enough scale to give rise to life is probably mistaken


Yeah, I was thinking the same thing. We know that Mars was once volcanically active (olympus mons is hard to miss).

Maybe the guy who wrote the press release just didn't quote all of what the scientist said. That does happen quite a bit in these short stories.
Torbjorn_Larsson_OM
3 / 5 (1) Nov 17, 2012
The clays and the organics created by impacts in wet environments are raising habitability, so raising prospects for life.

@ GSwift 7: "Unfortunately, this is a case where the null hypothesis must be disproven rather than the other way around. Until we actually prove that life formed somewhere else independently from Earth, we can't assume that there's life anywhere else."

Now you equivocate between the two senses of null hypothesis, statistical (the one you want to test) and physical (the base scenario you want to test against). The null hypothesis is that life is an easy process, because we observe that it happens so fast.

You want to test that of course, but it is the null hypothesis what the constraint gives us. (Science doesn't do "assumptions", it does constraints.) You are arguing that it isn't the null from a position of ignorance.
GSwift7
2.3 / 5 (3) Nov 19, 2012
The null hypothesis is that life is an easy process, because we observe that it happens so fast


No. We observe that life only started in one instance. No other bodies we can observe show any signs of life. Even a small variation away from conditions here on Earth, such as the difference between here and Mars, may have prevented it. Until proven otherwise, you must assume that life starting is rare. We only know of one instance, since all life here seems to have a common origin. If life is so easy to get started, wouldn't there be many different origins here on Earth? Wouldn't we still see new forms arising?

Furthermore, since we have yet to observe any planet that is likely to have characteristics truely similar to Earth, we have no grounds to assume how common such a planet is likely to be.
GSwift7
2.3 / 5 (3) Nov 19, 2012
You are arguing that it isn't the null from a position of ignorance


That's just observation. We only know of one place where life has formed. There is no way to place any further constraint on that until we find at least one other instance where life formed.

Saying that the null hypothesis is that life formes anywhere the conditions are right is absurd. That's like saying that anywhere we find life, there will be fish. After all, we observe fish, right? Therefore, they must evolve anywhere life is allowed enough time to evolve them.

You cannot place a constraint on anything from just a single observation. Therefore you are left with only two choices: As Arthur C Clark put it, there are two choices: Either we are alone in the Universe, or we are not. Either is terrifying.
Modernmystic
3.5 / 5 (2) Nov 19, 2012
Based on current observations, knowledge and assumptions my guess is that simple life is exceedingly common, multicellular life is fairly common, complex multicellular life is rare, complex multicellular intelligent life is exceedingly rare, and complex life with technological civilization might not exist outside our solar system.

That somewhat pessimistic view would be made far more pessimistic if we could not find evidence for simple life developing on Mars at some point when it had good conditions and plenty of time to do so.
GSwift7
1 / 5 (2) Nov 21, 2012
Based on current observations, knowledge and assumptions my guess is that simple life is exceedingly common, multicellular life is fairly common, complex multicellular life is rare, complex multicellular intelligent life is exceedingly rare, and complex life with technological civilization might not exist outside our solar system


I'm going to throw in the factor of time to further reduce your estimates. In 14 billion years, we know of only one instance where life formed, and it only started 3 billion years ago? Intelligent life is just a hundred thousand years, maybe a couple hundred thousand? Civilization less than ten thousand?

What are the odds of finding life, complex life, or civilization at any given place AND time?

What is the average life span of an average star?

How frequent are sterilizing events like planetesimal collisions or gamma ray bursts?

What percentage of planets eventually get ejected from their star?

How many planets are able to retain H?

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