Acharam evidências de fosfina na atmosfera de Vênus, sinal de que pode ter vida naquele planeta.
youtu.be/BBDyp06qp1U
90 vezes a pressão atmosférica da Terra, atmosfera de ácido sulfúrico e temperatura capaz de derreter chumbo (mais de 400⁰C).
Vênus nem sempre foi muito quente. E um estudo apresentado no Congresso Europeu de Ciência Planetária já sugeriu que o planeta possuiu oceanos e clima temperado por cerca de 3,5 bilhões de anos. Ademais, a região atmosférica de Vênus entre 50 e 55 km da superfície parece ser o lugar extraterrestre mais parecido à Terra no Sistema Solar em relação à temperatura e pressão atmosférica (1,07- 0,53 atm de pressão atmosférica e 75-27°C de temperatura). Nessa região, os tipos de micro-organismos extremófilos que precisariam existir seriam os acidófilos.Fernando Silva escreveu: ↑Ter, 15 Setembro 2020 - 09:15 am90 vezes a pressão atmosférica da Terra, atmosfera de ácido sulfúrico e temperatura capaz de derreter chumbo (mais de 400⁰C).
Se existirem, serão extremófilas ainda mais radicais que as daqui (água fervente e gases sulfurosos).
As bactérias do deserto de Atacama sobrevivem sem água:
Interview with Philip Ball, consultant editor of the journal "Nature" and Writer in Residence in the Chemistry Department of University College, London:
Q: Do you think liquid water is necessary for life to exist on other worlds? Alternatively, what do you think of suggestions that life elsewhere might evolve without liquid water, and instead make use of liquids like sulfur?
PB: I think that the discussion about this, with its attendant charges of "terra-centricity," generally fails to acknowledge what is really unique about water. The more we understand about biological water, the more we see that its unique ability to form a three-dimensional, hydrogen-bonded network enables it to participate in biochemical processes and not just to act as a passive backdrop.
At a somewhat crude level, life is about molecular processes, such as templating, molecular recognition and replication, which can be duplicated in non-aqueous solvents. But we find that even for the simplest organisms, many of the molecular interactions are facilitated by water in an extremely fine-tuned way. I'm not sure we know of any solvent that can play a comparable role in terms of enabling the kind of highly delicate chemistry that makes life possible.
If we accept that any form of life will require a comparable degree of chemical sophistication, it is hard to see what other solvent would make this possible. In other words, I'd put it like this:
1. Life most probably needs a solvent.
2. That solvent needs to perform an active, diverse, and flexible role.
3. Water is so far the only common liquid we know that is capable of this.
Q: You note in your book that in some ways, water is more like a crystal than a liquid. This brought to mind some theories that suggest crystals might have played a role in the origin of life, especially in regard to the chirality problem. Could water have played the role in life's origin that others have attributed to crystals?
PB: I say that water has attracted the attentions of people who have tended to be more interested in the crystalline rather than the liquid state, like Bernal and Pauling. But I'd say that water is literally like a crystal in just one respect: it has an unusually high degree of LOCAL ordering. But of course this is just on average -- there is nothing like a persistent ordered structure even on a local level. So I don't see that water could have played any kind of templating role like that proposed for some mineral crystals in the origin of life.
https://www.nasa.gov/vision/universe/so ... _Life.html
Não sou expert do assunto, mas pelo que li, a temperatura e pressão da atmosfera de Vênus é muito aquém da necessária para formar fosfina, diferente do que ocorre em Júpiter e Saturno.Fernando Silva escreveu: ↑Ter, 15 Setembro 2020 - 09:15 am90 vezes a pressão atmosférica da Terra, atmosfera de ácido sulfúrico e temperatura capaz de derreter chumbo (mais de 400⁰C).
Se existirem, serão extremófilas ainda mais radicais que as daqui (água fervente e gases sulfurosos).
Mas é fato científico que existem organismos terrestres que sobrevivem absolutamente sem água por longo período de tempo. Eles são chamados de anidrobióticos e alguns deles são animais (os tardígrados, por exemplo). Sabe-se disso devido ao fato de que esses organismos já foram postos no espaço sideral por muito tempo em experimentos humanos. Então, talvez alguns micro-organismos do deserto de Atacama também sobrevivessem à absoluta ausência de água.Gigaview escreveu: ↑Ter, 15 Setembro 2020 - 11:39 amNo Atacama a umidade é praticamente zero, mas não é zero e isso em termos moleculares pode representar muita coisa.
A biologia da vida depende de um solvente. Até o momento, não se conhece outro além da água.
Interview with Philip Ball, consultant editor of the journal "Nature" and Writer in Residence in the Chemistry Department of University College, London:
Q: Do you think liquid water is necessary for life to exist on other worlds? Alternatively, what do you think of suggestions that life elsewhere might evolve without liquid water, and instead make use of liquids like sulfur?
PB: I think that the discussion about this, with its attendant charges of "terra-centricity," generally fails to acknowledge what is really unique about water. The more we understand about biological water, the more we see that its unique ability to form a three-dimensional, hydrogen-bonded network enables it to participate in biochemical processes and not just to act as a passive backdrop.
At a somewhat crude level, life is about molecular processes, such as templating, molecular recognition and replication, which can be duplicated in non-aqueous solvents. But we find that even for the simplest organisms, many of the molecular interactions are facilitated by water in an extremely fine-tuned way. I'm not sure we know of any solvent that can play a comparable role in terms of enabling the kind of highly delicate chemistry that makes life possible.
If we accept that any form of life will require a comparable degree of chemical sophistication, it is hard to see what other solvent would make this possible. In other words, I'd put it like this:
1. Life most probably needs a solvent.
2. That solvent needs to perform an active, diverse, and flexible role.
3. Water is so far the only common liquid we know that is capable of this.
Q: You note in your book that in some ways, water is more like a crystal than a liquid. This brought to mind some theories that suggest crystals might have played a role in the origin of life, especially in regard to the chirality problem. Could water have played the role in life's origin that others have attributed to crystals?
PB: I say that water has attracted the attentions of people who have tended to be more interested in the crystalline rather than the liquid state, like Bernal and Pauling. But I'd say that water is literally like a crystal in just one respect: it has an unusually high degree of LOCAL ordering. But of course this is just on average -- there is nothing like a persistent ordered structure even on a local level. So I don't see that water could have played any kind of templating role like that proposed for some mineral crystals in the origin of life.
https://www.nasa.gov/vision/universe/so ... _Life.html
Pelo que eu saiba, a vida surgiu na água e depende dela, extremófila ou não.
In the absence of rain or dew, the cyanobacteria extract as much water from the gypsum crystals as they can [...]
Em regiões do Atacama longe do mar ou dos oásis, mesmo o que se encontra em cristais de gesso pode ser insuficiente ou inexistente. Ademais, água não é necessária para a sobrevivência de longo prazo em alguns organismos, e isso válido até para alguns animais macroscópicos. Isso é assim porque é falso dizer que sempre é preciso adquirir água do meio externo para adicionar água no organismo. Por exemplo, alguns animais do deserto conseguem produzir "água metabólica", como o rato-de-bolso mexicano: https://www.bbc.com/portuguese/vert-earth-37569444Gorducho escreveu: ↑Ter, 15 Setembro 2020 - 16:17 pmAquilo que eu falei:
Extreme microbes survive the desert by dissolving rocks with acidIn the absence of rain or dew, the cyanobacteria extract as much water from the gypsum crystals as they can [...]