The conventional view is that life began in or under the oceans. So not on land (and not in the presence of oxygen).
Mars needs oceans to support life - and so do exoplanets
Everyone knows that exoplanets need to be in the sweet Goldilocks spot (“not too hot, not too cold, just right”) next to their sun to support alien life: but now British boffins have said they reckon oceans might be necessary too. Artist’s impression of deep blue planet HD 189733b Researchers at the University of East Anglia …
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Monday 21st July 2014 16:00 GMT Anonymous Coward
"The conventional view is that life began in or under the oceans. So not on land (and not in the presence of oxygen)."
Not in the presence of oxygen?
DAMN YOU CHEMISTRY YOU'VE LIED TO ME ALL MY LIFE!!!!!
*Drops to knees, puts up a shakey hand*
Pourquoi!!!!!
(hint: in H2O the O stands for something)
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Monday 21st July 2014 17:31 GMT phil dude
evidence...
About 600 million years ago, there was the Cambrian explosion, which was the evolution of multicellular life, of which eukaryotes are the majority descendants. Fish (or the earliest thing we would recognise as a fish) did not evolve for about 100 million years, being distinct by the appearance of the veterbral column.
There is evidence to suggest that gills evolved to maintain ion exchange before oxygen exchange.
Liquid(state) water is probably crucial but probably sufficiently moist air would suffice (microbes don't care). But life really only needs lots of time....
In the only example we know of, it took >3 billion years to get to "fish-like".
P.
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Monday 21st July 2014 18:45 GMT Paul Crawford
Not oxygen?
I think the original commentard was referring to this:
http://en.wikipedia.org/wiki/Great_Oxygenation_Event
Cyanobacteria are postulated to be the cause of the first major organism extinction as they produced plentiful O2 by photosynthesis which is toxic to obligate anaerobes.
So the first life on Earth did not need atmospheric oxygen, but of course it did need it bound with hydrogen in water.
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Monday 21st July 2014 23:12 GMT Scroticus Canis
Re: Not oxygen?
Not to mention it only took about 900 million years of prokaryote life before cyanobacteria produced enough oxygen to precipitate all the dissolved iron out of the oceans (as rust) and for free oxygen to be available. Then eukarotes could evolve and later produce multicellular forms. Gills of any kind are recent in comparison.
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Monday 21st July 2014 15:40 GMT lorisarvendu
Re: Bleeding obvious ?
Probably nobody reading this. But all the populist media ever report is that a planet has been found in an orbit that allows liquid water. They never qualify to their readers that being in that zone doesn't automatically mean there is water.
Venus is in our Goldilocks zone too. So that's only a 33% hit rate in our Solar System.
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Monday 21st July 2014 20:59 GMT the spectacularly refined chap
Re: Bleeding obvious ?
Venus is in our Goldilocks zone too. So that's only a 33% hit rate in our Solar System.
Over geological time it isn't - if it formed in a similar manner to the Earth it certainly had water at one point but has lost it: it's close enough to the Sun that water vapour could boil off and completely escape the atmosphere, unlike Earth where it is firmly trapped. Venus is dry as bone as a consequence, and it is that that has caused such an extreme climate - no water means no rain to wash CO₂ out of the atmosphere, which shuts down the long term carbon cycle resulting in a dense CO₂ atmosphere and generally unpleasant climate.
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Monday 21st July 2014 15:43 GMT John Gamble
Re: Bleeding obvious ?
"Is there anyone reading this who *didn't* think this?"
The impression I get is that the temperature swings had not been considered -- you can't just have a quantity of water in your planet of lakes to sustain life, you need to have a truly deep ocean to handle the heat flow.
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Tuesday 22nd July 2014 01:14 GMT Steven Roper
Re: I'd also add...
"..a working magnetic core but I guess a little factor like that got overlooked in all the excitement."
And I'd wager a large moon is probably essential to the formation of said magnetic core. Note that of the terrestrials only Earth is equipped with a large moon to roil its interior with tidal forces and thus set up the conditions for the formation of a magnetic field. These tidal forces also create the conditions necessary for vulcanism and plate tectonics, both of which in turn maintain the carbon cycle and are also essential for life.
Without any large moons, Venus and Mercury lack these forces, and thus also lack the vlucanism and tectonics, and the magnetic fields necessary to protect life from solar radiation and prevent ablation of liquid water via solar wind.
If this is the case, then it's likely life-bearing planets are much less common than we might think, since besides being in the Goldilocks zone a planet would additionally need to have formed a large moon in a stable orbit to create the conditions required for life. And I would hazard that the number of terrestrials with large moons is significantly less than terrestrials in stars' Goldilocks zones, with the probability of both occurring being minute indeed.
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Tuesday 22nd July 2014 03:49 GMT Don Jefe
Re: I'd also add...
A magnetic core is only necessary if you want your compass to read correctly.
I don't like the term 'dead planet' though. 'Devoid of life' is more accurate. It also eliminates the philosophical conundrums implied in the planet being a living creature and we're running around shitting and pissing on it as well as two (or more) Humans having dirty sex while stacked on top of an involuntary participant.
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Tuesday 22nd July 2014 09:11 GMT jason 7
Re: I'd also add...
Well the magnetic core also deflects such stuff as cosmic rays etc. that if they hit the surface would spoil your day.
Massive amounts of radiation tends to kill most things. Hence the term 'dead planet'. It's engine stopped a long time ago.
I really don't understand why they go on so much about terra-forming Mars.
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Monday 21st July 2014 16:23 GMT Anonymous Coward
Not sure about this
I have a nagging doubt about confident assertions of planets' suitability to support life that seem to be based on the assumption that if a planet doesn't have an environment that behaves in just the same way as Earth's then it can't support life, because life as we understand it on Earth requires that environment. Even here there are examples of life existing in similarly "impossible" places, like deep sea vents. I very much doubt that there's a unique chemistry necessary for life to evolve.
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Monday 21st July 2014 18:36 GMT hkeller
Re: Not sure about this
What exactly is life? If we take life to be a self-reproducing system based on available energy and matter resources, then the possibilities are limited. The Periodic Table has only so many naturally-occurring elements, many of which are relatively rare.
Life requires a certain complexity. The atoms making up its molecules must support that complexity. Life requires a liquid solvent in order for its chemistry to function. One may imagine a solid-state life, but its metabolic rate would be such that a million years would be required for a single generation. Once you go through all of the possibilities, carbon comes out as the best choice -- so much better that second-best isn't really in the running. Water also comes out as the best solvent for reasons of its ubiquity as well as all of its unusual properties.
As scientists have now shown, DNA can be made of compounds other that A, C, G, & T. There's lots of room for a different genetic code. There are also many amino acids other than those we use that could be involved in life, but the simplest ones probably will be part of making proteins.
Could there be another system entirely? It's possible but extremely unlikely. So it is that we will probably never encounter such a life form.
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Monday 21st July 2014 19:13 GMT Keith Langmead
Re: Not sure about this
While the mass media may word it that way, I think from a scientific point of view the point is in identifying those planets that definitely CAN support life rather than excluding others.
If you assume that there may be many forms of life, and they may be capable of surviving on any planet in any solar system, then suddenly any planet is a likely candidate. If that's the case where do you focus your attention? It's far simpler to focus on what we know for sure, and base the search on conditions that make life possible here (and which as far as we know preclude it on Venus or Mars). Besides, in searching for planets with Earth like conditions they're not only looking for planets which may already have life, but also planets which could support us were we one day able to reach them.
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Tuesday 22nd July 2014 07:53 GMT Down not across
Re: Not sure about this
I have a nagging doubt about confident assertions of planets' suitability to support life that seem to be based on the assumption that if a planet doesn't have an environment that behaves in just the same way as Earth's then it can't support life,
Ah, at least its not just me who gets miffed at this (at least as often potrayed by media) seeming ignorance that a different environment could well sustain life that has evolved in that environment.
As The Firm parodied: It's life Jim, but not as we know it.
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Monday 21st July 2014 16:52 GMT Scott Broukell
We've found it ! . . .
The weather is very unsettled, undergoing some sort of not-so-well understood change at the moment, it rains a lot, violently at times, and is known to be a bit nippy in just the right places for occupation. This meteorological trend is thought to be gathering pace. There would appear to be significant quantities of a variety of pollutants which may contribute towards proportionate negative outcomes with regard to plant cultivation and animal ingestion thereof. Desertification has been expanding for some time in many areas once considered prime for possible habitation where sustained human existence would very probably come up against major obstruction going-forward. It would seem that over many years some sort of discarded/waste material has built up in the seas and on land, to such an extent that it too threatens the sustainability of both plant and animal existence globally. So, on the whole, it should feel just like home (yeah!).
The bad news is; we haven't got a cat in hells chance of getting there in time before the devastating results of all of the above take hold here on Earth. But hey!, you did ask us to go look and we would like to thank you for the funding whilst it lasted.
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Monday 21st July 2014 18:37 GMT hkeller
Re: We've found it ! . . .
We will be on Mars within two decades, possibly only a little more than one decade.
Search for "Martian Rhapsody" to see a scenario (in fiction) and a nearby discussion of the realities.
When it comes to moving a significant portion of Earth's population to Mars, I agree that it's hopeless. The best we may do within a few decades is a few hundred people if we can make Mars habitable.
Water is there. Land mass is the same as Earth's. Planet size is 11% of that of the Earth, but gravity is 38%. No one knows whether 38% is helpful, harmful, or neutral with respect to human health. The air is thin, about 1% of Earth, and poisonous -- mostly CO2 with too much CO to allow use in compressed form even if the CO2 were not toxic alone. The "soil" is highly oxidized making its use in agriculture a serious problem.
Except for the gravity, every problem can be solved **in theory**. The cost of oxygenating the Martian atmosphere is huge and would take around a century with currently available technology. To be breathable, you'd have to generate 670 million tonnes of O2.
Still, visionaries such as Elon Musk are working on how to get us to Mars and how to colonize it later on. It will happen before 2050 when the Earth is scheduled for a climate meltdown.
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Monday 21st July 2014 18:36 GMT hkeller
Water, water, everywhere
Water is made is space from exploding stars in great quantity. It constantly falls on all of the planets. A few tens of millions of years will fill an ocean. Water is constantly being lost to space too. UV light in the upper atmosphere splits water in to hydrogen and oxygen. The hydrogen tends to escape much more readily than the oxygen.
The amount of oxygen in our air was minute for Earth's early history. It took a huge algal bloom (or the equivalent of cyanobacteria) a long time to fill the air with poisonous (to life in those times) oxygen. They were literally poisoning themselves and other life with their exhaust. Sound familiar?
Oxygen in the air killed off much of the anaerobic bacteria. The rest is found in anoxic environments. Oxygen also allowed evolution to sculpt new species, especially multi-cellular forms that require more energy, which can be obtained with oxygen-based energy in biological systems.
As a couple of people have noted, Mars and Venus are theoretically in the liquid water zone around our sun. Mars has the misfortune of being small. Its core cooled and lost its magnetism. Lack of a magnetic field and a 100-times stronger solar wind in the early solar system combined to blow away the Martian atmosphere over millions of years. The frozen water falling on Mars today is quickly sublimated and lost to space. It's likely that oceans of frozen water are beneath the surface of Mars. Venus is big enough but did not manage to get rid of its CO2 before succumbing to a runaway greenhouse effect. Now, you can melt lead on its surface. No oceans there.
For much more on traveling to Mars, see the Educational Technology and Change Journal (etcjournal dot com) where a lively discussion has been taking place regarding the potential for human settlement on Mars. The first two chapters of a novel about just such an undertaking also appear there.
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Monday 21st July 2014 18:36 GMT hkeller
excellent science
The science in this article is excellent. Some may draw incorrect conclusions from it, however. For example, it's possible that both Mars and Venus had substantial oceans early in their existence. If oceans are necessary for life, then both could have had life. Neither has any active life today.
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Monday 21st July 2014 19:27 GMT Stevie
Bah!
"Researchers at the University of East Anglia"
Ah, the old Alma Mater rises above the nasty e-mail scandal of the oughties and reclaims the Crown of Science.
The only way this could backfire is if some clod makes reference to climate.
"Oceans have an immense capacity to control climate."
Godsdammit!
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Monday 21st July 2014 19:35 GMT Destroy All Monsters
Planets without Endorian Wood Terrorists.
Wasn't there another study that said that having a practically dry planet like Earth would be exceptional, with most planets covered in multi-kilometer deep oceans, as is the case of the Europa for example?
There must be some extreme sailing going on on these blueballs. I would buy a ticket!
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Monday 21st July 2014 21:04 GMT Another User
Re: Planets without Endorian Wood Terrorists.
About 70% of the surface of the earth is covered by water. "Dry" land is a result of plate tectonics and volcanism. Both of these mechanisms rely on a hot core. This same hot core also enables the magnetic field. As already mentioned the magnetic field protects the atmosphere from the solar wind.
So maybe another planet which could sustain life would have to be quite earth-like.
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Tuesday 22nd July 2014 01:27 GMT Anonymous Coward
Man's gotta know his limitations.
It is very difficult to think of everything that needs to be done, especially when you are planning a planet with a working ecology. We have yet to come up with a reliable means of keeping people inside an airtight container. The one study that has been conducted indicates that human borne bacteria build up on the surfaces inside the habitat until they reach dangerous concentrations.
Now, consider the plight of the poor climatologist who cannot seem to take water into account in his modelling...
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Tuesday 22nd July 2014 09:50 GMT Bunbury
There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy
The goldilocks zone is a bit misleading. Yes, if you want life like ours that is critically dependant on liquid water and oxygen and the only source of heat is the star then there is a zone at which you are more likely to have both present.
However, look at our solar system. What is in the goldilocks zone? Venus, Earth, Mars. Where is there liquid water that we know of? Earth, Europa. Not a very good fit. And anaerobic life doesn't need oxygen.
It might well be that the middle of the goldilocks zone with abundant water and oxygen is more likely to produce complex life than other environments. Water is an excellent solvent so can be used in more processes than other liquids, for example. And the presence of oxygen on Earth gave rise to rapid evolution in comparison to the preceding span of time.
It's a tendency of the self absorbed to think that everyone else must be like them.
Biting the hand that feeds IT
