lunes, octubre 25, 2010

Wonders of the Solar System - Aliens (V)

V - Aliens

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Vida en las profundidades del océano

The Atlantis is the launch vessel for Alvin, one of the world’s most rugged submarines. Built like a spacecraft, it’s designed to explore the deepest depths of the ocean. (…) It’s one of only a handful of submarines that can withstand the colossal pressure of the deep ocean.

Could life exist down here? Hundred atmospheres, cold, dark, no signs of sunlight at all, it’s pitch-black there… you would say no. I would say no. But the depths of the ocean are not lifeless. Illuminated by Alvin’s lights, we found oasis of life in the deserts of the ocean floor.

This underwater city is one of the most bizarre environments in our planet. It’s built around a hydrothermal vent, a volcanic opening on the Earth’s crust that pumps out clouds of sulphurous chemicals and water heated to nearly 300ºC. And somehow, life has found a way to thrive in these most extreme conditions. (…) It’s not only bacterial blobs. Those are real complex organisms.

For me, the fascinating thing about finding life down here, is that the conditions on the deep ocean floor are the most similar in many ways to the conditions on worlds hundreds of millions of kilometres away, out there in the Solar System. (…) If life can not only survive but even flourish in these conditions, you gotta feel that it is much more likely that life can also survive and flourish out there in the Solar System.

Condiciones para la vida

Life is pretty much… only chemistry. (…) For life to exist, you only really need three things. First of all, you need the right chemistry set. (…) 96% of me is only made of four [elements]: carbon, nitrogen, oxygen and hydrogen. Secondly, you need a power source, a battery, something to make a flow of electrons that powers the processes of life. Here on Earth, most life uses the power of the Sun. And thirdly, you need some kind of medium for life to play itself out there, for those processes to happen. (…) Here on Earth it’s water.

If you want to see how important water is to life, there’s no better place to come than the Atacama desert in Chile. The soil here is more sterile, inhospitable operating theatre. In fact, scientists have looked for the most basic form of life, bacteria, and they’ve found absolutely nothing.
All deserts are characterized by a lack of moisture. But the Atacama takes that to the extremes. The Sahara is 50 times wetter than the Atacama. It’s this dryness that explains why nothing can survive here. (…) This seemingly fundamental link between water and life is driving the search for life out there in the Solar System.

The Earth is the only planet that currently has liquid water on its surface. The other planets are either too close to the Sun, like Mercury, and dry. Or they are too far away. Saturn’s rings are made of water. But in the depths of space, it’s frozen in lumps of solid ice. But that doesn’t mean that liquid water has never existed elsewhere in the Solar System. And if it has, we should be able to find the evidence, because wherever water goes, it leaves its footprint.

Vida en Marte

These are the Scablands, a remote part of the nothwesern United States. It’s one of the most spectacular places to come to see how water carves its signature into the landscape. (…)
This entire landscape was created at the end of the last ice age. 200 miles to the east lay a huge lake, held in place by a wall of glacial ice. When that wall ruptured, over 2,000 cubic kilometres of water, swept out in a single, catastrophic event. (…)
As the flood waters tore across the landscape, they carved out this twenty mile long canyon. And at its head, it left these giant horseshoes. At over 400 feet high and five miles across, this was the largest waterfall the world has ever known.

The Scablands reveal the characteristic signature that water carves into the landscape. It’s a signature that can be seen from space. But not just on the Earth.
When we turn our telescope on our next door neighbour, and prime candidate for finding alien life, the planet Mars, we find almost identical features cut into its surface. The red planet is covered in outflow channels, straight, wide canyons, exactly like the scablands. And they are filled with identical geological features.

It all suggests that similar huge floods once tore across the surface of Mars. (…) But the floods that created them may only have lasted a matter of days. For life to get a foothold, you need more than that. You need areas of standing water, lakes and rivers that persist for millions of years. (…) In order to prove that, (…) we’ve sent an army of robotic explorers to the surface of the planet. (…)
On of the most significant discoveries was made on November 2004. The Opportunity Rover was examining an impact feature, called the Endurance Crater, when it detected deposits of a remarkable mineral.

This is the world’s largest salt works on Baja Península, in México. What they do here is they pump see water into this lagoons and let water evaporate. What they are after is this stuff, sodium chloride. But at different stages, different salts of different minerals crystallize out. (…) This is Gypsum, and it’s exactly the same stuff that Opportunity found on the surface of Mars. What is interesting about that discovery is how you make Gypsum. (…) It’s calcium sulphite dehydrated. The only way to make Gypsum is to have calcium and sulphite ions in the presence of liquid water.

The discovery of Gypsum has helped build a picture of an ancient Mars that was much warmer and wetter. Subsequent discoveries of Gypsum in networks of sand dunes suggest that large areas of Mars were once covered in standing water. And where there is standing water, there is the chance of life. (…) It looks extremely inhospitable, (…) but if you just dig a tiny bit below the surface, you see that this layer of Gypsum is only a few millimetres thick, and immediately below is turns to a greeny colour. That’s green because that is bacteria that thrived in these seemingly inhospitable conditions.

But although it may have once been more hospitable, any liquid water has long since disappeared from the surface of Mars. About 3 billion years ago, it died as a planet. Its core froze, and the volcanoes that had produced its atmosphere, ceased up. The solar wind stripped away the remains of that atmosphere. Any liquid water would have evaporated. (…) It left the surface of Mars too cold and too exposed and too dry to support life. It’s highly unlikely that there will be life in the surface of Mars today. (…) But maybe we are just looking in the wrong place.

Detailed pictures of the surface show the entrances to caves (…) We know there may be water down there. Satellite data shows permafrost, ice frozen in the soil. Deep below the surface that ice may melt to form liquid water.

Vida bajo la superficie

There is another living planet hidden beneath the surface, that exists in completely different conditions. It raises fascinating possibilities for the caves on Mars.
This is the Cueva de Villa Luz in Tabasco, México.(…) It’s the definition of a hostile environment to me, because it’s full of hydrogen sulphite gas… very toxic.

That doesn’t mean that nothing lives here. In fact it’s teaming with life. (…) But the really interesting life is found in the depths of the caves, where the concentration of gas is high enough to set up my alarm. Down here, far from the light of the Sun are organisms, whose energy source comes from the air around them. They use hydrogen sulphite gas bubbling up through these streams. The same gas that is poisonous to me, is their source of life. (…) These are snotites. (…) These guys breathe in hydrogen sulphite and oxygen and produce sulphuric acid!

The snotites are not alone. Organisms that can extract energy from the minerals around them are found under the ground all over the world. (…) It’s so successful, that it’s thought that there may be more life living beneath the Earth’s surface than above it. (…) Why couldn’t organisms like snotites survive and flourish beneath the surface of Mars?

How could you detect it? There is a tantalizing clue that there may be something interesting below the martian surface. These are termites. (…)In the process of digesting wood, they produce the gas methane. And because they are so many, they are estimated to produce 50 million tons of methane and pumping it into the Earth’s athmosphere every year. And it’s not just termites.

[Methane] is all produced either biologically or by active geological processes, like mud volcanoes. That makes it all the most surprising that methane has been detected in the atmosphere of the supposedly dead planet Mars. (…) First measurements appeared to be showing only tiny amounts, but closer observations have revealed that the gas is concentrated in a handful of plumes that vary with the seasons. In the warmer summer months, thousands of tons of the gas is released from vents in the surface. Something under the surface of Mars must be producing it. It may be coming from previously unknown geological processes, but it could be that it’s coming from a biological source. (…) Termites use symbiotic bacteria to digest wood, called archaea. (…) And archea are the most common organism beneath the surface of the Earth [and] thriving in many of Earth’s most extreme environments.

Vida en Europa

This is central Iceland and this time of year in November, it’s an increasingly inhospitable place. (…) There is pretty much visible life here at all. (…) It’s because these places are so cold and inhospitable, that they are of increasing interest to astrobiolgists, because discoveries in these frozen places of Earth have raised new hope of finding life amongst the icy worlds of the outer Solar System. (…) We have found one world which is of particular interest.

The ice moon Europa is about the same size as our moon, and it’s the smoothest body on the Solar System. Its surface is made of an unbroken shell of ice, though its etched with a network of mysterious red markings. It exists at a chilly -160ºC.

The surface features tell you a lot about what is going on deep beneath the ice. (…) Deep cracks crisscross the surface of Europa. At higher magnification, we see areas where the ice has been broken and icebergs are jumbled up before refreezing. We see the same formations in sea ice on Earth. (…) It’s the way the cracks are broken and fractured that provides compelling evidence that there is liquid water on Europa. (…) Its ice shell is sitting on top of a salty ocean that may be a staggering 100km deep.

The cave tunnels into the heart of the glaciar. (…) What astrobiologists find on this ice makes us think that Europa could be teaming with life.
-For a long time it was thought that ice microorganisms were present only in a state that it’s called deep anabiosis –suspended animation- It’s now becoming quite clear that that it isn’t necessarily the case for all the microorganisms. There may be others who are actually actively living in the ice.

-We have bacteria
-These are organisms that have been trapped in that glaciar for thousands of years.
-Beautiful. You are seeing life in ice
-That’s amazing!
-We now know that some microorganisms are capable of actually causing the ice to melt, because they generate essentially anti-freeze proteins. They change the temperature at which ice goes from a solid state to a liquid state. And they could have been forming little tiny pockets, maybe only a few microns in diameter. (…) But then that bacteria is not in a glaciar but it’s in an ocean. (…)

You can clearly have bacteria in the frozen ice near the surface crust. And the thing that is the most exciting to me is that the surface crust of Europa has a wide variety of colours that are highly suggestive of microbial life. There is a very strong possibility that the ice of Europa may contain viable living microorganisms.


That question, are we alone in the Universe, (…) is one of the most important questions that you could possibly ask… [and] we have a chance of answering it.

3 comentarios:

Nuri148 dijo...

teeming with life

Vivi dijo...

Desde el cosmos a los microorganismos, los mortales terminamos diciendo: "No somos nada..."
Será el futuro de nuestro planeta similar al de Marte,cada vez más inhóspito?

Silvi dijo...

Qué interesante toda esta serie. Y es posible que sin tu tamiz, nunca lo hubiera leído. Son excelentes las comparaciones con cosas raras de la Tierra para hacer los paralelos. La producción de metano por parte de las termitas me dejó patidifusa.