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Many planetary scientists suspect that Mars, now cold and very dry, once had a liquid water ocean covering parts of its surface. But this does not necessarily mean that the Red Planet was ever a tropical paradise… a recent paper by a team of astrobiologists suggests that Mars was much more bitter than balmy.
Astrobiologist Alberto Fairyn and colleagues have published a paper in the journal Nature Geoscience suggesting that the marked absence of phyllosilicates in Mars’ northern lowlands is indicative of a cold ocean environment, with perhaps even a boundary of frozen glaciers.
Phyllosilicates are minerals that, on Earth, are found readily in marine sediments and sedimentary rock that was formed in the presence of an ocean environment. These same minerals have also been seen via orbiting spacecraft spectrometers to be present in sediments located in Mars’ equatorial regions, but not in the northern latitudes. Fairyn and his team, intrigued by the disparity between existing models that described Mars as being once warm and wet and the lack of phyllosilicates in the north, used new climatic and geochemical models to deduce that Mars’ northern oceans must have been consistently near freezing, with portions even covered over by ice.
The current presence of moraines in the northern highlands also suggests that glaciers may have surrounded these frigid seas, which may have prevented the transportation of phyllosilicates down to the northern ocean basin. Again, to use our own planet as an analogy, moraines are rocky debris left over from the movement of glaciers. Their existence on Mars strongly suggests a period of early glaciation.
The research by Fairyn et al. contradict – or, more aptly, combine – two leading concepts of early Mars: one, that it was cold and dry and the existence of any liquid water was restricted to the equator for small periods of time; and two, that it was once globally warmer and wetter and sustained rivers, lakes and oceans of liquid water for extended periods.
Thus a cold Mars with an Arctic, icy ocean seems to be a more fitting causation of the current state of the planet, suggests Fairyn.
More research is planned, including running through more low-temperature models and hunting for ancient coastal areas that may have been impacted by icebergs. This will no doubt prove to be a challenge since much of the evidence is now buried deep beneath newer sediments and volcanic deposits. Still, Fairyn is confident that his model may help solve a long-standing debate over the history of the Red Planet.
Read more in an article by Bob Yirka on PhysOrg.
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Jason Major is a graphic designer, photo enthusiast and space blogger. Visit his website Lights in the Dark and follow him on Twitter @JPMajor or on Facebook for the most up-to-date astronomy awesomeness!
It’s ok to have an opinion, even if it is wrong. There is no other world in our solar system besides Earth that is as remotely as inhabitable as Mars. Understanding the current state of the planet is necessary if we ever want to have any chance of colonizing it in the future. It is only impossible if it is never attempted.
Besides, if the taxpayers of the United States choose to fund space exploration, I’m not exactly sure why it would be considered a waste of money as long as they are seeing progress.
I’m so sorry about your writing skills, Vishal. Do you need money to go to school?
Science is never a waste of money. Building the research tools creates jobs. Jobs for engineers, jobs for cooks, jobs for cleaning lady, jobs for bus drivers…..
And in return we get these cool new technologies.
Your spelling is horrible ,this is not a text message no need for poor gramma , hard to take your comment seriously
It is possible that early Mars provided conditions which permitted pre-biotic chemistry and maybe the formation of life. If so then the line in Jurassic Park, “Life will find a way” might mean that life has adapted to later cold and dry conditions. The observation of gully washes from crater sides indicates that liquid water probably exists under the surface, and analogues of prokaryotes might live there in some ecological network.
Mars is the most similar to Earth compared to other planetary bodies. While there might be biology under the ice crusts of Europa and other jovian moons, it will be a long time before we get around to probing down there. Sending a robotic drilling rig out there will be a daunting and expensive mission. So Mars remains the best option for finding extraterrestrial biology.
LC
Agreed.
The case for a (at least long time) warm Mars was always marginal, but even so there was a transition period with plenty of time for abiogenesis.
Also, the longstanding volcanism (and the fate of Spirit, trapped in a vent remain) shows how hydrothermal vents would have provided refuges for abiogenesis and/or life even if the above possibilities panned out for some reason or other.
I’m thinking Enceladus or Titan with sample return will be easier, but Mars is still in the running toward becoming the planetary system’s next extraterrestrial biosphere.
Missions to explore the surface of jovian moons will be very complex, and return missions even more difficult. Europa also requires a powered landing all the way to the surface, while at least Titan can be reached with parachute landings. If we want to break through ice crusts that involves planting a drilling rig there, with the robotics capable of running it.
I am skeptical of the idea of life in the sub-ice water of Europa and related moons. The problem is that to have life you need an energy flow. While the temperature of this water might be palatable for life, I doubt there is much energy flow. You need to have some first law of thermodynamics involved
dQ = dU + dW,
where dQ is the thermal energy flow, dU = TdS or internal energy unavailable to do work and dW the work. The natural gas law is often used here with S = Nk and dW = pdV. The Gibbs version of the first law replaced dQ with the enthalpy for a chemical reaction. If everything is adiabatic with dQ = 0 there is then no energy flow.
LC
LC, could some of these theorized bodies of water – particularity Europa – be affected by tidal energy from their host planets? It is my understanding that these slow moving Rossby waves could impart significant kinetic energy.
The other possibility is some sort of internal activity within the lunar core, but this seems unlikely.
I think tidal forces that change with the rotation of the moon are the primary energy source for warming in these bodies. Io is very active as a result. It again comes down to a question of energy density and sufficient energy flow. The temperature differences which drive biology on Earth are fairly large. A human standing on the surface of a jovian moon would find themselves becoming rapidly cold as they melt and vaporize the ice layer they are standing upon. In particular frozen nitrogen would rapidly vaporize, the hapless astronaut would find that their own body heat and the heat source in the spacesuit is driving a sort of geyser. This temperature difference is occurring with a small number of moles. Temperature differences which drive these fumaroles, such as seen with Enceladus, occurs over 10s of kilometers of ice or water. See above my argument with the first law of thermodynamics.
LC
A Titan sample return will be complicated, but landing is simpler than Mars I take it, and its primary biosphere if any should be surfaced based.
An Enceladus sample return is presumably but a few scoop runs through the jets, if a probe can take it. (I believe I have seen a claim that a single run will collect too little organics.)
You should be able to use Titan for aerocapture (if that is the term) around Saturn, so all parts of an Enceladus sample-return mission except relaunch delta-v to Earth will be rather simple compared to a Mars sample-return mission.
As for habitability of Europa, I agree there too, in that hydrothermal vents are a must to supply minerals in the first place. The pristine ocean is likely caught between two ice sheets, as I remember it. (Less likely mineral source would be impactors, whose remains may reach through or convect down.) Vents, if they exist, supply enough energy for both abiogenesis and a continued biosphere.
This is the reason I too are somewhat cautious about the habitability of ice moons. They make for good research subject though.
I was not thinking about the Enceladus jets. That is a signature of some thermal flow. I am not sure whether that is sufficient to drive complex chemistry. The cryro-regions of the solar system are interesting, where it appears that small temperature differences are capable of driving active storms. At lower temperatures we can have
dQ = dU + dW
with both dQ and dU small per mole, but where dQ – dU = dW is sufficient to drive a large scale system, such as the huge storms we observe. For instance, dU = NkdT, where even though dT might be very small the number of molecules N is very large — eg the entire atmosphere of Saturn. Yet dW per mole is quite small, which makes me wonder whether there is sufficient energy density in this region to drive biochemistry. The ATP — > ADP + P_i, P_i phosphorylated on a peptide, involve 76kcal/mol.
However, it might be possible to orbit through the jets and collect material. The return issue is complicated though. This might reveal something of the chemistry associated with the interior.
While speculations about Titan are interesting, I doubt there is anything biological there. At temperatures around -180C water or ice is hard as rock, and alternative biochemistry ideas I find to be strained.
LC
That is all good and well, but theoretical and invalidated by that Earth organisms live of hydrothermal vents as their only energy (and nutrient) source.
Again good and well, but putting the cart before the horse yet again. Predictive models and methods have chemistry imbalances as signatures of life, and Titan has the most of those today.
We need to learn what is happening whether it is life or not, since it affects how we will search for life signatures both remotely (exoplanet spectra) and in situ (our own system).
And again we have vents as possible refuges. Titan methane must be resupplied somehow, and it could happen by communication with the underlying ocean that is the more realistic source.
All this is if not strained so too unconstrained. So I prefer not to speculate too much but observe that Titan currently formally passes our best test for life better than, say, Mars.
In order of difficulty I think sample return places Mars < Enceladus < Titan, but difficulty of meaningful sample return in the sense of getting to test for likely trace fossils may be Enceladus < Titan < Mars.
If Titan should be on that list I don't know. I think so, and I believe I have seen plans that Titan scientists thinks so too (i.e plans for a sample-return).
As for energy considerations driving biochemistry, we _know_ biochemistry happens in molecular clouds that have some tens of Kelvin temperature. Radiation of various kinds drive that.
This is btw the energy source that has been proposed to drive Titan biochemistry, by photolysis in the upper atmosphere, and by trapping oxygen radicals in fullerenes and transporting them down, at its surface.
So, since bond formation are bound to happen, what _are_ the requirements for metabolism? In a cold environment, degradation would be minimized, so no need for rapid replacement and growth (R&G).
And metabolism is at its core steady state push-pull coupled reactions, pull one molecule off for R&G (say, placing a lipid into a cell membrane to compensate oxidation) and you will pull raw material. Enzymes are not actually supplying energy but lowers enthalpic or entropic barriers.
It is cellular actuators that use energetic coenzymes such as ATP, the cellular energy currency, for transport, assembly et cetera. This is done in an environment that has energetic surplus, because it can happen.
Putative life at other temperatures may have to settle for diffusional transport, and use virtually no energy at all. Slow, sensitive to environmental change, but still possible.
But as I said in other comments here, I expect local sources will provide surplus energy where we see the most interesting chemistry happen.
I think I will have to reserve any positive opinions about biological prospects on Titan. The energy transferred by ATP is Q = 76kcal/mol, or about 10joules per mole. Computing the temperature equivalent by assuming it just produces heat Q — > CT, which in a calorimetry with water is
1836j/mole = 74.5 j/(mole•K) T
or 24.6K, which is the exptected temperature rise of 18g of water. This means that biology more or less requires at least this sort of temperature change with a molar equivalent of water. This means that the energy source with biology is somewhat compact.
There is organic chemistry in nebula and the rest, but this is due to slow transitions as molecules bump into each other with the presence of the odd photon here and there. This is a far cry from the energetics of biochemical path ways. I suspect that something similar holds for cyro-moons. There may be temperature gradients across tens of kilometers of ice which vaporizes nitrogen or other elements we ordinarily think of as gases.
With the Viking disappointment I think people started to grasp at straws. It was only a little over 100 years ago that it was popularily thought Mars was biologically active, and even might have had canals made by Martian ETIs. The prospect for life on Mars has returned a bit, and the wets cool Mars of the past might have permitted the evolution of Martian life. It might now inhabit the substrata of rock. I think Mars is the best chance for finding extraterrestrial biology.
LC
I think I will have to reserve any positive opinions about biological prospects on Titan. The energy transferred by ATP is Q = 76kcal/mol, or about 10joules per mole. Computing the temperature equivalent by assuming it just produces heat Q — > CT, which in a calorimetry with water is
1836j/mole = 74.5 j/(mole•K) T
or 24.6K, which is the exptected temperature rise of 18g of water. This means that biology more or less requires at least this sort of temperature change with a molar equivalent of water. This means that the energy source with biology is somewhat compact.
There is organic chemistry in nebula and the rest, but this is due to slow transitions as molecules bump into each other with the presence of the odd photon here and there. This is a far cry from the energetics of biochemical path ways. I suspect that something similar holds for cyro-moons. There may be temperature gradients across tens of kilometers of ice which vaporizes nitrogen or other elements we ordinarily think of as gases.
With the Viking disappointment I think people started to grasp at straws. It was only a little over 100 years ago that it was popularily thought Mars was biologically active, and even might have had canals made by Martian ETIs. The prospect for life on Mars has returned a bit, and the wets cool Mars of the past might have permitted the evolution of Martian life. It might now inhabit the substrata of rock. I think Mars is the best chance for finding extraterrestrial biology.
LC
I think I will have to reserve any positive opinions about biological prospects on Titan. The energy transferred by ATP is Q = 76kcal/mol, or about 10joules per mole. Computing the temperature equivalent by assuming it just produces heat Q — > CT, which in a calorimetry with water is
1836j/mole = 74.5 j/(mole•K) T
or 24.6K, which is the exptected temperature rise of 18g of water. This means that biology more or less requires at least this sort of temperature change with a molar equivalent of water. This means that the energy source with biology is somewhat compact.
There is organic chemistry in nebula and the rest, but this is due to slow transitions as molecules bump into each other with the presence of the odd photon here and there. This is a far cry from the energetics of biochemical path ways. I suspect that something similar holds for cyro-moons. There may be temperature gradients across tens of kilometers of ice which vaporizes nitrogen or other elements we ordinarily think of as gases.
With the Viking disappointment I think people started to grasp at straws. It was only a little over 100 years ago that it was popularily thought Mars was biologically active, and even might have had canals made by Martian ETIs. The prospect for life on Mars has returned a bit, and the wets cool Mars of the past might have permitted the evolution of Martian life. It might now inhabit the substrata of rock. I think Mars is the best chance for finding extraterrestrial biology.
LC
I am afraid have to concur with LC here re: Titan, there does not seem to be enough energy gradient to drive such a process even over the long time scales and certainly not at the static temperature floor, or ceiling, there is just not a gradient to work with.
This is a tough call too, as I want so much to extend more than just a doubt to the exciting potential you describe Torbjörn.
The gradient is just too gradual, there is not enough slope and the external sources which would supply energy might supply too much for some types of life in the setup, or too little and too late for others.
Now a symbioses might stand a chance within this framework and I hope someone cares to figure which two, or three maybe, types of life would work out with these parameters and the interaction each could supply to the group effort.
That is much too complex for my brain today.
Mary
First I want to correct an error of mine. Radiation will both feed energy into biochemistry and be a source of degradation. Therefore there will be a need for some minimum rate of metabolism.
Second, there is no need for steep gradients in metabolism. Let us look at this obsession with ATP in the context of biology.
1. There is no need for gradients to produce ATP.
For historical reasons ATP was likely first produced in glycolysation.
However most ATP production in modern cells are driven by accumulating membrane ion potential differences. This obviate the need for reactions which result in exactly the correct free energy to make ATP. The cell does not waste energy or produce unnecessary heat.
Famously, the chemiosmotic theory led to a Nobel prize.
Of course it would be more lengthy to evolve chemiosmosis or its analogies than simpler glycolysation, if less energy is around than on early Earth. But still doable, more so since our own cells evolved and prefer that method anyway.
2. There is no need for ATP in metabolism.
ATP coenzyme energy is used in metabolism to make “irreversible reaction”. I.e. their main function is to make ratchets in metabolism as need be.
As I described earlier, simple “pull chemistry” suffice for that. Again, it is not a shortcut that would be available without a massive energy flow as on Earth. Which is why we happen to use it.
3. There are other energy sources than ATP.
Radiation produced energetic oxygen radicals trapped in fullerenes (for Titan, say) has already been mentioned.
As for energy considerations driving biochemistry, we _know_ biochemistry happens in molecular clouds that have some tens of Kelvin temperature. Radiation of various kinds drive that.
This is btw the energy source that has been proposed to drive Titan biochemistry, by photolysis in the upper atmosphere, and by trapping oxygen radicals in fullerenes and transporting them down, at its surface.
So, since bond formation are bound to happen, what _are_ the requirements for metabolism? In a cold environment, degradation would be minimized, so no need for rapid replacement and growth (R&G).
And metabolism is at its core steady state push-pull coupled reactions, pull one molecule off for R&G (say, placing a lipid into a cell membrane to compensate oxidation) and you will pull raw material. Enzymes are not actually supplying energy but lowers enthalpic or entropic barriers.
It is cellular actuators that use energetic coenzymes such as ATP, the cellular energy currency, for transport, assembly et cetera. This is done in an environment that has energetic surplus, because it can happen.
Putative life at other temperatures may have to settle for diffusional transport, and use virtually no energy at all. Slow, sensitive to environmental change, but still possible.
But as I said in other comments here, I expect local sources will provide surplus energy where we see the most interesting chemistry happen.
On Earth, cold seas are some of the richest in life, even far beneath the sea ice of Antarctica. I don’t see any reason why this may not have once been the case on Mars as well!
There were also fumeroles and hot vents, which may have been the catalyst for the chemical evolution into life.
LC
“Life will find a way”. How very true this has been on this planet. Life has colonized virtually all imaginable environments on earth – which is why you’d think that would also apply to mars if there was any life at all. Okay, let’s admit that ie some prokaryotes may have developed in seasonal and briny underground water.
Then how would life not have colonized more habitats? Even the surface? I mean even on earth there are some bacteria that can naturally resist the UV levels seen on the surface of Mars… Why would life have stopped at these habitats – with all the time it’s presumably had? Why haven’t the Viking landers and subsequent rovers been unable to find the slightest trace of organic material in very different places? Being a biologist, I find it extremely naive to think life would be confined to a few specific habitats when we all know that “life will find a way” indeed. In other words if we haven’t found it at all anywhere else on Mars – there’s no reason why life should be in these briny water streams.
I don’t think “life will find a way” is a suitable metaphor for the respective processes of abiogenesis and habitability. It makes the tails of the later out to characterize two processes with widely different characters.
Abiogenesis was fast on Earth, so presumably an easy process. It should be centered on transitions from heat to cold chemistry, the earlier supplying sufficient reaction speed to enable metabolic like pathways, the later providing an environment suitable for genetic material.
On most or all planets that would mean the likeliest era when it caught life is when the newly aggregated planet cools down as a whole. After that, plate tectonics and hydrothermal vents are the more localized but enduring environments.
Early life is fragile, so it would take some time to evolve into something akin to Earth habitability. Extremophiles are later invention, if the root is between bacteria and archaea or within bacteria.
If life makes the transition to evolve into hardier cells as we know them, the main drivers characterizing habitability are temperature (cell temperature of ~ 20 – 40 degC maximizes productivity) and water (100 % maximizes productivity).
So on Mars, if life survived, its main habitat would be below ground. The surface breaks down organics and the atmosphere is replete with carbon dioxide, so such remains would not be a prediction from an underground biosphere.
I would expect emissions perhaps. But the current methane observations may simply be noise problems of probes and Earth based observations respectively.
I was more excited by the recent images of, seemingly, seasonal wetting processes on the Mars surface.
Either the color changes are all brine induced.
Or there are flowering of prokaryotes in there too, wouldn’t it be? Most prokaryotes have some icky color on biologists growth plates. =D
And they don’t see the water yet, at least from orbit. So what is it? On Earth, the most prominent seasonal color change, outside of ices, would be biosphere induced I believe…