The scientific study of the origin, evolution, distribution, and future of life in the universe.

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Carl Sagan's ideas on the self-extermination of technological civilizations

I've read (though I can't remember the source) that Carl Sagan speculated that intelligent life forms tend to evolve on various worlds, then exterminate themselves. If true, then I'd like to learn ...
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What are the tests performed by NASA's Mars rovers to establish that life could survive on the planet?

I am particularly interested in the Mars Rovers, which are out there trying to find life. Do they believe that the tests they perform are sufficient to verify the existence of life (Also please ...
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23 views

What are the expected characteristics of the soil suitable for life and how are they quantified? [closed]

My question is related specifically to astrobiology. I am interested in the criteria astrobiologist look for when they attempt to determine if the elements necessary for life are present on an ...
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39 views

What is the reasoning behind the Drake Equation?

I've read a bunch on how the Drake Equation is constructed, but I'm not able to understand some of the reasoning behind it. $$ N = R_* \cdot f_p \cdot n_e \cdot f_l \cdot f_i \cdot f_c \cdot L \cdot ...
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What is the highest pressure at which plants can survive?

Inspired by this awesome question, I'm looking for the corresponding maximum: what is the highest air pressure at which plant life can survive? For example, Venus's atmosphere is about 90x as dense ...
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67 views

Is it possible for humans to digest and live on food that isn't based on DNA or RNA? [closed]

Our bodies digest food using enzymes that have evolved to convert food here on Earth. Could we even possibly get nutrients from something we haven't evolved alongside? - Is it possible for humans to ...
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227 views

A colony of humans are sent to an alien world, at what point would the descendants evolve to be genetically incompatible with Earth humans? [closed]

I recently heard about the evolution of the London Underground mosquitoes, and how they have changed genetically enough that they almost can no longer reproduce with above ground mosquitos. Since this ...
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51 views

How much divergence would be needed for classifications as astrobiology?

It is possible that life has invaded mars or the moon by way of probes rovers and other man made tech. How many years or generations of sequential and phenotypical diverge would be necessary to ...
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99 views

Life on other planets [duplicate]

first of all I'm not sure if I should post this here or in the astronomy stack. I think biologist are more likely to answer my question. To make it short: Why when looking for any sort of life on ...
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130 views

What would classify those findings of the University of Sheffield experiment as aliens?

It's in the news that some experiment was able to capture some alien specimens during a meteor shower: ...
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77 views

In our solar system which other planet could have been in the “habitable zone” in the past?

With changes in our solar system, such as planets moving away from the sun and the reduction in solar radiation, which other planets in our solar system could have been, in the past, in a suitable ...
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Can life subsist on anything else but water?

Inspired by an answer to a previous question. It's hypothesized that extraterrestrial life could be based on silicon rather than carbon as its main structural element. Are there similar theories ...
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Why must a planet be in a star's “habitable zone” to have life?

I have seen many articles that talk about a star's "habitable zone" as the ring around it which is just the right temperature for planets to have liquid water, which is necessary for life. My question ...
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If life is discovered on another planet, will it likely be classified using the current domain/kingdom/phylum system?

This may be a stupid question showing my lack of understanding of taxonomy, but I was wondering if the current classification system we use contains broad enough categories to include new life forms, ...
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85 views

Should we be looking for extra-terrestrial life on comets?

I have just read What elements are a possible basis for life? and I find myself wondering whether instead of seeking advanced life-forms at remote locales a La SETI, and perhaps fundamentally ...
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296 views

Is there life on other planets and if so how frequent?

Some shed tears of joy as the news about the successful landing of the Mars Rover Curiosity came in. Then the most comprehensive 3D map of our observable universe was published. 2012 is literally an ...
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What would need to be discovered to prove there is extraterrestrial life?

Curiosity is on the Martian surface and is equipped with a slew of laboratory equipment. What would Curiosity need to discover to prove there is or has been life on Mars? Would it have to find DNA (or ...
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242 views

How did the nucleobases in the Murchison meteorite form?

The Murchison meteorite is an important piece of evidence for abiogenesis, because it contained nucleobases from extraterrestrial origin, as this Wikipedia article explains. These results ...
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749 views

What is the lowest pressure at which plants can survive?

What is the lowest pressure at which plants can survive? How the plants behave in a Martian-type atmosphere? Is there any plant that can survive such atmosphere? Can a lichen grow at Martian ...
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477 views

How do biological communities at deep-ocean hydrothermal vents migrate between vents?

Much interest in the astrobiology community has been generated by the discovery of biological communities populating deep-ocean hydrothermal vents (i.e. "black smokers"). (1) These ecosystems rely on ...
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259 views

Is there any convincing evidence for the existence of nanobacteria?

The existence of nanometer scale microorganisms has been proposed and used explain several phenomena including morphological structures in a martian meteorite (ALH 84001) and implication in the ...