Alpha Centauri might be habitable after all

Brian G Turner

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#1
alpha-centauri.jpg


A long-term study of Alpha Centuari has dispelled fears that life couldn't survive in that star system.

NASA's Chandra X-ray Observatory made observations every six months from 2005, and discovered that the radiation wouldn't be so bad as originally expected.

At around 4 light years away, Alpha Centauri is the nearest star system to Earth. It comprises three stars: Alpha Centuari A, which is very similar to our sun; and Alpha Centuari B, which is a smaller star that orbits it to form a binary pair. At a very extended orbit around both is the small red dwarf Proxmia Centauri.

Originally it was thought that interactions between Alpha Centuari A and B would result in a flood of radiation that could sterilize any nearby planets. Although no planets have yet been found around these two stars, data from Chandra shows that radiation levels are actually similar to our own system.

So if any planets a safe distance from those stars might be capable of supporting life - not just indigenous where conditions allow, but also future colonists from Earth.

However, it's not all good news - Promixa was found to emit deadly bursts of X-Rays during solar flares during its solar cycle. This does not bode well for Proxima b, a rocky planet about the size of Earth that has already been detected in orbit around Proxima, in what should have been a habitable zone.

There remains hope for the future, though - the James Webb telescope will take a closer look for planets in the Alpha Centuari system, after it launches in 2020.

Additionally, the race is on to design a space probe capable of visiting Alpha Centauri, with the private company Breakthrough Starshot aiming to have a viable project "within a generation", while NASA is also looking to send its own interstellar probe there in 2069.

[IMAGE: Alpha Centuari A and B are so close that they appear as one star in the above image, with Proxima circled red.]
 
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SilentRoamer

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#2
The discussion of "habitable" bothers me. Habitable by whom? The single example of life we have at the moment? Such a large sample of 1!

Maybe a lot more radiation is conducive to whatever life form may or may not be out there.

It reminds me of the novel Wheelers - where some Jovian blimps sit and think how awful life must be for anything developing on "Blue Poison" with water and oxygen being highly poisonous to their own life.

I would hope that when we do find life, it is varied and interesting by equal measures, in all likelihood I expect most life dies at the bottom of its own gravity well. I think a truly advanced species might necessarily be spacebound already.

Thanks Brian I found this very interesting.
 

night_wrtr

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#3
Maybe a lot more radiation is conducive to whatever life form may or may not be out there.
Good point, and I agree that whats harmful to us could be required for life's survival elsewhere.

I would hope that when we do find life, it is varied and interesting by equal measures, in all likelihood I expect most life dies at the bottom of its own gravity well. I think a truly advanced species might necessarily be spacebound already.
I guess that depends where on the life scale The Great Filter falls. It may get us all at some point, but its hard not to think there are at least a few Type 1 or 2 civilizations out there.
 

Brian G Turner

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#4
The discussion of "habitable" bothers me. Habitable by whom? The single example of life we have at the moment? Such a large sample of 1!
Well, if we ever do start colonizing space and need a base at Alpha Centauri, at least we don't need to fear being irradiated by the local binary stars. :)

But I do agree - life constantly surprises us - but the world of science tends to dislike speculation without supporting data, so we're stuck with our limited sample until we're able to broaden it. Hopefully future research on icy moons around Jupiter and Saturn will help with that. :)
 

night_wrtr

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Well, if we ever do start colonizing space and need a base at Alpha Centauri, at least we don't need to fear being irradiated by the local binary stars. :)
I am a little disheartened that it will be so many years before we send something in that direction. Still, it would be out of our lifetimes more than likely before we came near the system.

Even Laser Sails would take a 100 years? Is there any plan to create a telescope like Hubble or James Webb and launch it like a probe into deep space? For instance, if we wanted to scout Alpha Centauri, I would think that the time investment to get clearer images would have a large payoff for the increase in detail it could find as it came nearer to the system.
 
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#6
Given how close B gets in one part of its orbit, I would think life on the planet would have to be awful flexible to put up with the orbital shifts and extra light of second full sized sun passing through the equivalent of Saturn's orbit, but having 1000 times the mass of Jupiter. The whole "three body problem".

It would be an ecological catastrophe every 79 years.
 

BAYLOR

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#7
Given how close B gets in one part of its orbit, I would think life on the planet would have to be awful flexible to put up with the orbital shifts and extra light of second full sized sun passing through the equivalent of Saturn's orbit, but having 1000 times the mass of Jupiter. The whole "three body problem".

It would be an ecological catastrophe every 79 years.
So basically not ideal for human habitation.
 
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#8
So basically not ideal for human habitation.
I don't think the habitability being discussed is for earth life. While humans can survive anywhere living in a tube, I'm not so sure that recreating an earth-like environment on a planetary scale is really practical, even if you have the right orbit, day/night cycle, gas mix, magnetosphere, etc.

The planet around Alpha Centauri sounds ideal for breeding life that is extremely hard to kill - like an ocean wide monoculture.
 

BAYLOR

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#9
I don't think the habitability being discussed is for earth life. While humans can survive anywhere living in a tube, I'm not so sure that recreating an earth-like environment on a planetary scale is really practical, even if you have the right orbit, day/night cycle, gas mix, magnetosphere, etc.

The planet around Alpha Centauri sounds ideal for breeding life that is extremely hard to kill - like an ocean wide monoculture.
It's going to centuries before we ship to Alpha Centauri to find out.
 
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BAYLOR

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That seems like a rather long time, considering.
Possible mode of transportation .
1. Multigenerational ship
2. Sleeper ship with in crew in suspended animation .
Both concepts are well beyond technological means and probably will be for another 2 centuries .
 
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#12
Possible mode of transportation .
1. Multigenerational ship
2. Sleeper ship with in crew in suspended animation .
Both concepts are well beyond technological means and probably will be for another 2 centuries .
Yeah, no idea where you pull these prognostications from.
 

night_wrtr

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#14
Possible mode of transportation .
1. Multigenerational ship
2. Sleeper ship with in crew in suspended animation .
Both concepts are well beyond technological means and probably will be for another 2 centuries .
I would imagine multi-generational ships would come long after we develop more advanced engines, though. Once we have a ship that is capable of travelling faster and more efficiently, then that aspect would probably come into play.

And I say that because if we send a multi-generational ship to A.C., but perfect Laser Sails, or some other engine technology later on that gets us further up the speed of light %, a faster ship could be launched decades later and reach the destination before the first ever does.
 
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#15
If we do find life on other worlds, how can we justify colonizing such a planet just because it is suitable for our species. We would be a little upset if the same thing happened to us here on Earth. The only answer is to find a totally uninhabited world and terraform. Difficult yes but we should not assume we have the right to expand humanity by usurping worlds with their own indigenous life.
 
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#16
If we do find life on other worlds, how can we justify colonizing such a planet just because it is suitable for our species. We would be a little upset if the same thing happened to us here on Earth. The only answer is to find a totally uninhabited world and terraform. Difficult yes but we should not assume we have the right to expand humanity by usurping worlds with their own indigenous life.
Would you consider bacteria or even plant life 'inhabited'. What are the ethical barriers to putting un-self aware life in a conservatory and repurposing their former territory?
 

BAYLOR

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If we do find life on other worlds, how can we justify colonizing such a planet just because it is suitable for our species. We would be a little upset if the same thing happened to us here on Earth. The only answer is to find a totally uninhabited world and terraform. Difficult yes but we should not assume we have the right to expand humanity by usurping worlds with their own indigenous life.
Even if we did find such a world, we would never be able to walk on it without space suits. We couldn't breath the air because in all likelihood , the native viruses and the bacteria could prove lethal to us. Also any viruses or bacteria that we carry could likewise prove to be lethal to whatever lifeforms are living on the planet.
 
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#18
Even if we did find such a world, we would never be able to walk on it without space suits. We couldn't breath the air because in all likelihood , the native viruses and the bacteria could prove lethal to us. Also any viruses or bacteria that we carry could likewise prove to be lethal to whatever lifeforms are living on the planet.
Why would alien life even have viruses that could interact with DNA based earth life? That's like saying your DVD player is going to catch a computer virus from you smartphone.
 
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#20
If it's based on the same or similar amino acids, then that would definitely be a possibility. There seems no reason at the moment to presume that life on Earth is the biological exception in the universe. :)
I don't think we're the exception, but I think the chances that virus would be able to co-opt the functions of a cell it isn't programmed for are close to zero. We use the same DNA as trees, but very few viruses can infect either. Aliens made of the same amino acids might end up with something very similar to DNA, but to end up with cell structures that function like earth life is a stretch, and compatible cell structure to carry out the reproduction instructions that make viruses dangerous even more unlikely.

DNA is like binary, how the DNA spells things is like Fortran and what the Fortran program says is like an operating system. For an alien virus to infect us they would need to not just use DNA, but happen to be coded to work with operating systems that use ribosomes, permeable lipid cell walls, ATP for energy, etc.

The reality is that DNA based life might not have a cellular structure at all. Like an ostrich egg, alien life forms could be large organisms that appear to be a single cell. They could have "cell" walls made of calcium rather than lipids. There is nothing about DNA that means that it needs to encode life remotely like ours, just be made of similar ingredients.

That's why a remain doubtful that viruses - which reproduce entirely by subverting our system program - are likely to work in any sort of universal way - there are too many orders of magnitude of necessary parallelism in the evolution to have that kind of compatibility. Which is very similar to how even members of the same genus can't generally be crossbred - even small differences matter.

I am of the mind that 'anything is possible', but the level of interactivity necessary for alien viruses to commandeer and reprogram our cells seems outlandishly unlikely. Billions to one. Like me reproducing with a dandelion.

A flesh eating 'bacteria-like lifeform' would be more of a concern, because that just requires us to be roughly digestible into useful compounds before whatever incompatible toxins (if any) slow the replication or growth of the infection. But that's a simpler process more like rot or digestion.
 

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