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Like rising waters from a flood, the evidence for past water on Mars — and large amounts of it – keep mounting. The latest study, which combined the analysis of water-related features including scores of delta deposits and thousands of river valleys with a look at the possibility of a global hydrosphere on early Mars, found that a vast ocean likely covered one-third of the surface of Mars some 3.5 billion years ago.
“Collectively, these results support the existing theories regarding the extent and formation time of an ancient ocean on Mars,” said Gaetano Di Achille and Brian Hynek from the Univesity of Colorado at Boulder, in their article in Nature Geoscience, “and imply the surface conditions during the time probably allowed the occurrence of a global and active hydrosphere integrating valley networks, deltas and a vast ocean as major components of an Earth-like hydrologic cycle.”
The idea of an ocean on Mars has been repeatedly proposed and challenged over the past two decades, and just last week, another study proposed lakes in the Hellas Basin region on Mars. This new study provides further support for the idea of a sustained sea on the Red Planet during the Noachian era more than 3 billion years ago.
More than half of the 52 river delta deposits identified by the CU researchers — each of which was fed by numerous river valleys — likely marked the boundaries of the proposed ocean, since all were at about the same elevation. Twenty-nine of the 52 deltas were connected either to the ancient Mars ocean or to the groundwater table of the ocean and to several large, adjacent lakes, Di Achille said.
The study is the first to integrate multiple data sets of deltas, valley networks and topography from a cadre of NASA and European Space Agency orbiting missions of Mars dating back to 2001, said Hynek. The study implies that ancient Mars probably had an Earth-like global hydrological cycle, including precipitation, runoff, cloud formation, and ice and groundwater accumulation.
Di Achille and Hynek used a geographic information system, or GIS, to map the Martian terrain and conclude the ocean likely would have covered about 36 percent of the planet and contained about 30 million cubic miles, or 124 million cubic kilometers, of water. The amount of water in the ancient ocean would have formed the equivalent of a 1,800-foot, or 550-meter-deep layer of water spread out over the entire planet.
The volume of the ancient Mars ocean would have been about 10 times less than the current volume of Earth’s oceans, Hynek said. Mars is slightly more than half the size of Earth.
The average elevation of the deltas on the edges of the proposed ocean was remarkably consistent around the whole planet, said Di Achille. In addition, the large, ancient lakes upslope from the ancient Mars ocean likely formed inside impact craters and would have been filled by the transport of groundwater between the lakes and the ancient sea, according to the researchers.
A second study headed by Hynek and involving CU-Boulder researcher Michael Beach of LASP and CU-Boulder doctoral student Monica Hoke being published in the Journal of Geophysical Research–Planets — which is a publication of the American Geophysical Union — detected roughly 40,000 river valleys on Mars. That is about four times the number of river valleys that have previously been identified by scientists, said Hynek.
The river valleys were the source of the sediment that was carried downstream and dumped into the deltas adjacent to the proposed ocean, said Hynek. “The abundance of these river valleys required a significant amount of precipitation,” he said. “This effectively puts a nail in the coffin regarding the presence of past rainfall on Mars.” Hynek said an ocean was likely required for the sustained precipitation.
“One of the main questions we would like to answer is where all of the water on Mars went,” said Di Achille. He said future Mars missions — including NASA’s $485 million Mars Atmosphere and Volatile Evolution mission, or MAVEN, which is being led by CU-Boulder and is slated to launch in 2013 — should help to answer such questions and provide new insights into the history of Martian water.
The river deltas on Mars are of high interest to planetary scientists because deltas on Earth rapidly bury organic carbon and other biomarkers of life and are a prime target for future exploration. Most astrobiologists believe any present indications of life on Mars will be discovered in the form of subterranean microorganisms.
“On Earth, deltas and lakes are excellent collectors and preservers of signs of past life,” said Di Achille. “If life ever arose on Mars, deltas may be the key to unlocking Mars’ biological past.”
Hynek said long-lived oceans may have provided an environment for microbial life to take hold on Mars.
Source: CU-Boulder
I wander if Mars was brown and blue as shown on the image 3.5 billion years ago. May be it was blue and green with lots of clouds.
I doubt Mars had any extensive life on its surface. It might have either had some pre-biotic chemistry or maybe it developed microbial life. Further maybe that life has persisted to this day by adapting to the harsh conditions which exist now. As for green though, I doubt Mars ever had forests or plant covering.
LC
Well, IMO, the possibility of microbial life and algae that may have developed on Mars during its Noachian epoch, when conditions were more favourable for abiogenesis, and also the possibility that life may still exist today in some form in underground caverns, is more plausible than the recent wild speculation of ‘life’ on Saturn’s moon Titan — too bloody cold!
This is great! Last I read about the river valley network they couldn’t find any global pattern but regional (i.e. drainage areas). That it would match up to a water level was a nice surprise!
But it’s 1/10 the mass.
Though the same water/solid ratio is likely a coincidence, since latest I heard the main part of our volatiles must have been delivered as an asteroid veneer according to Kr isotope measurements. Likely the same holds for Mars.
Earth had stromatolites @ 3.5 Ga though, and those testable for fossil traits specifically consisted of fossils of green cyanobacteria. Let’s say blue-green oceans then. 😀
There are objective reasons to be more excited than usual.
– Mars has one certain chemical imbalance, methane, compared to Titan’s one (acetylene) or two (and hydrogen); I hear that Titan’s lack of ethane may be made up by it being part of the seas or something such so that can be counted out as of yet. The unlikelihoods multiply.
– Mars has likely a continuous igneous activity explaining the methane (combined ALH 84001 and shergottite results). Good for habitability, but disastrous for using its presence alone as a biomarker.
– If its cold for life, it is cold for the purported inorganic catalysts that would reconstitute methane from hydrogen and acetylene. Biochemistry makes good catalysts though.
And there is plenty of energy to extract out of that, so why would the cold matter? Whatever consumes the chemicals, assuming the measurements and modeling is correct, does it at an appreciable rate. If life evolved at those temperatures, it would have to generally metabolize at corresponding rates, wouldn’t it?
Out of the two planets, IMHO Titan looks more agreeable to life right now.
Oops, I forgot on Mars methane. As always I must note that the problems of methanogenesis are largely underestimated:
– On Earth, methanogenesis shares the core enzymes of aerobic methanotropy [Chisterdova et al, 2004]. (Which in turns likely evolved from aerobic methylotropy, which has one enzyme less.) It had to wait for an oxygenated atmosphere to get started, to get going in the likely also late eukaryote sister group the archaebacteria.
Methanogenesis seems to be one of the two latest metabolisms to evolve. (Since anaerobic methanotropy is nested within methanogens, it is then the latest.) That seeming difficulty of extracting energy out of methane metabolism in similar conditions translates directly to Mars. As here any early life main energy potential provider would have been sun light.
[Since Titan putative biosphere energy input is through atmospheric photo-catalysis, the similarities ends there. The neigh only way life could get started would be to evolve around methanogenesis in some radically different form.]
OK I’ve still not heard about the small detail that it’s waaay too cold on Mars to have any liquid water. Furthermore, it’s been getting warmer for the last 4.5 billion years. So how could any significant amounts of liquid water ever exist on Mars? I’d really like to hear an explanation.
Mars would have still had a molten core 3.5 B years ago keeping it’s magnetic field active which would have allowed it to have a much more substantial atmosphere than it has now. Because of this temperatures would have been higher allowing liquid water to flow on the surface. Depending on the abundance of salt/minerals in the water, the atmospheric pressure, etc., these would all affect how liquid water could exist on Mars. It’s hard to say how the planet looked that long ago. We do not know enough about the planet itself to make secure opinions on this just yet.
If there was water, the atmosphere was denser.
Apparently even today the reverse is a fact. The atmosphere density, equatorial max temperatures and salinity conspire to make liquid water a possible occurrence in the deepest ravines on Mars. (Similar to how Phoenix saw such water.)
There’s supposed to be some papers on that somewhere. (There’s a regular commenter (Bad Astronomy? Here? Can’t remember.) who use to point that out every time someone claims the opposite.)
Torbjörn Larsson OM:
Because, as far as I understand, abiogenesis would require ‘warm’ conditions for life to get started in the first place; once started, only then can it adapt (or evolve) to its changing (in this case colder) environment.
@IVAN3MAN_AT_LARGE
“Because, as far as I understand, abiogenesis would require ‘warm’ conditions for life to get started in the first place”
How long should such a warm period need to be?
What about life travelling on an asteroid that went from a warmer part of the solar system and crash landed?
I doubt if martian life ever evolved to the point of complex baterial(like) communities such as what composed stromatalites they were probably not enough to colorize Mars much. The issue of martial life, past or present is very much an open question though.
LC
Olaf:
Assuming that some hypothetical organism somehow survived (within cavities in the asteroid) the UV radiation, cosmic rays, and ionizing stellar winds from the Sun, while the asteroid was travelling around the Solar System, and also survived the heat resulting from the asteroid entering the atmosphere of a planet or (as in the above mentioned case) the moon Titan, then that organism would not be able to adapt fast enough to its new and harsh environment once the asteroid had “crash landed” on the planet/moon in question..
@ IVAN3MAN:
By what mechanism, and how was that tested?
@ LBC:
It is always good to have doubts! But they should be founded. What is wrong with the hypothesis that if Mars had roughly the same conditions as Earth up to the same age, we would expect to find the same biota?
The main differences is weaker sunlight, weaker magnetosphere (of which the later obviously didn’t make much difference up to that time) and absence of plate tectonics.
I don’t think the weaker photo-intensity makes any difference for successful photosynthesis though, we could grow plants on Mars in the existing light AFAIK.
Absence of plate tectonics (PT) makes considerably fewer hydrothermal vents after a while, but at about the time life arose there shouldn’t be much of a difference. It likely took quite a while for our own PT to appear; though that is uncertain.
OK, I’ll amend the magnetosphere analysis; in some theories, say early “hydrogen” atmospheres giving organics et cetera, the conditions at the top of the atmosphere makes a huge difference. But there are alternate pathways to organics, the discussed hydrothermal vents being one.
Torbjörn Larsson OM:
I was referring, above, to the Miller–Urey experiment.
Maybe the best place to explore Mars is around the shoreline of this ancient ocean. Maybe there are fossil stromatalites there.
My point is that Earth at this time probably also had very little green visible from space. I suspect that any ETI who visited Earth might have had to search a bit to find life.
LC
@ IAL:
Good. But Miller-Urey isn’t a complete theory for abiogenesis but for getting probiotic chemistry.
And even for that there are other alternatives; ironically one of those are the freeze-thaw cycles that Miller came up with after noting that a freezer did a better job, with respect to nucleic acids IIRC.
So I don’t think these experiments demonstrate a hinder for low temperatures.
@ LBC:
I see your point, fair enough.
@ Torbjörn,
I presume that you’re referring to this case, as reported in a Discover Magazine article, “Did Life Evolve in Ice?”, in which a frozen ammonia-cyanide blend, in a vial, had coalesced into the molecules of life: nucleobases, the building blocks of RNA and DNA, and amino acids, the building blocks of proteins.
Interesting results, but although they are “the molecules of life”, it does not mean that ‘life’ itself can get started under such cold conditions (-108 °F; -78 °C), does it?
The water could be green — or even reddish.
It all depends on whether the iron precipitated out of the water, and whether or not the water is oxygenated.