Alpha Centauri might be habitable after all

[johndsal]

Bacteria and plant life on another planet indeed means it is inhabited. We could never know if it was sentient because they may have a means of communication we do not yet understand. Also, as life on Earth has evolved from bacteria, so might the life forms on another world evolve. We should not assume that any planet is ours to colonise because the life we find there is not as advanced as we think we are. As I said before, how would we feel?

 

[Vertigo]

We go to a lot of effort to try and prevent exploitation of sensitive environments on our own planet. NASA has teams dedicated to preventing contamination of other planetary environments visited by our probes and not just to avoid the risk of misinterpreting our own biology for extra-terrestrial biology, but rather because of the ethical issues of such contamination. There's no reason to think we wouldn't make equally strenuous efforts regarding an exoplanet discovered to have life.

All that said, our efforts to protect our own native environments have not exactly been a spectacular success; there are always plenty of people who strive to exploit any environment that might show a profit and there's no reason not to expect the same to be true with regard to exoplanets.

 

[Brian G Turner]

Why would alien life even have viruses that could interact with DNA based earth life?

Why not?

 

[johndsal]

What happens if we arrive at a planet that has a fairly advanced civilisation? Do we rely on their good nature to allow us to settle there? Do we try and take it by force because we could be the losers. If we are there because we are trying to save the human race, we cannot put the future of our species at risk by going to one planet. That means finding other alternatives and that is why I feel terraforming is the answer. Admittedly it would be expensive, technically difficult and take millennia.

 

[Vertigo]

What happens if we arrive at a planet that has a fairly advanced civilisation? Do we rely on their good nature to allow us to settle there? Do we try and take it by force because we could be the losers. If we are there because we are trying to save the human race, we cannot put the future of our species at risk by going to one planet. That means finding other alternatives and that is why I feel terraforming is the answer. Admittedly it would be expensive, technically difficult and take millennia.

I would hope we wouldn't attempt to take it by force but I wouldn't bet on it. If the other civilisation is 'friendly' and the future of the human species is at risk then maybe we could leave a small colony with them whilst we look for other alternatives; more than one basket for our eggs.

 

[night_wrtr]

What happens if we arrive at a planet that has a fairly advanced civilisation? Do we rely on their good nature to allow us to settle there? Do we try and take it by force because we could be the losers.

I hate to say this, but humanity doesn’t have a very good track record for politely asking for settlements. If we did find an advanced civilization on another planet, I truly hope that our species has developed a better common morality, but I find it hard to believe, in a situation where humans are looking to survive by relocation, we wouldn’t repeat history.

 

[Vertigo]

Sadly if it came down to a truly "us or them" scenario I really can't see us humans quietly going off into space to die out of sight, and in fact in such a scenario I'm not sure which side of the fence I'd be, if there is truly no chance of cohabitation. It's an interesting moral dilemma and one touched on in many SF books including my recent reading of both Children of Time and All these Worlds - in the former we manage to cohabit, in the latter we are forced to exterminate.

 

[night_wrtr]

The same can be said in reverse. Would we be willing to allow settlement on our planet? It's (probably true across all galactic civilizations should there be others) in our nature to self-preserve at whatever means necessary.

Haven't read those, but Children of Time looks like an interesting premise.

 

[johndsal]

Could we convince the natives that we come in peace? Could we be convinced if they came to us? From what I have heard lately, most scientists, astronomers etc think that the only surviving entities throughout the universe will be artificial life forms that will see us as we see insects

 

[Vertigo]

The same can be said in reverse. Would we be willing to allow settlement on our planet? It's (probably true across all galactic civilizations should there be others) in our nature to self-preserve at whatever means necessary.

Haven't read those, but Children of Time looks like an interesting premise.

Children of Time by Adrian Tchaikovsky is a very good serious bit of hard SF, All these World is the last in our very own @Dennis E. Taylor's Bobiverse trilogy (leastways I think it's the last), slightly less serious hard SF in the sense that the Martian is slightly less serious hard SF ie. serious but lots of snarky humour in it.

Could we convince the natives that we come in peace? Could we be convinced if they came to us? From what I have heard lately, most scientists, astronomers etc think that the only surviving entities throughout the universe will be artificial life forms that will see us as we see insects

Those, of course, are all the big questions, to which Cixin Liu's The Three Body Problem gives a very depressing answer.

 

[Onyx]

What happens if we arrive at a planet that has a fairly advanced civilisation? Do we rely on their good nature to allow us to settle there? Do we try and take it by force because we could be the losers. If we are there because we are trying to save the human race, we cannot put the future of our species at risk by going to one planet. That means finding other alternatives and that is why I feel terraforming is the answer. Admittedly it would be expensive, technically difficult and take millennia.

I think this assumes a rather B-movie type scenario where humans make this spectacular effort to cross some enormous gulf, make no long range flybys and arrive so desperately out of supplies that we have to colonize the planet to survive. The "desperate colonist" trope is a little ridiculous.

If we are actually set up to colonize a planet, we would have tons of supplies. If the planet is in a remotely normal solar system, we can mine raw material and refuel the ship from asteriods, comets, moons, gas giants. If we sent probes ahead we would know that the planet is occupied and might decide not to risk the ship by diverting, since ships really aren't all that tough.

Alien planets are not likely to be easily habitable, and if that's the big plan, then the preparations and alternatives to that plan are going to exist in depth. It isn't going to be like rushing off the plane when it lands in Fiji.

 

[night_wrtr]

Those, of course, are all the big questions, to which Cixin Liu's The Three Body Problem gives a very depressing answer.

well, there is another book added to my list.

I think this assumes a rather B-movie type scenario where humans make this spectacular effort to cross some enormous gulf, make no long range flybys and arrive so desperately out of supplies that we have to colonize the planet to survive. The "desperate colonist" trope is a little ridiculous.

Maybe, but this is because humanity seems like it is headed for some kind of catastrophe at all times. Whether we are just capable of sending ships into space or ready to colonize, it is a method that works because audiences like it and it seems like a real scenario.

If we are actually set up to colonize a planet, we would have tons of supplies. If the planet is in a remotely normal solar system, we can mine raw material and refuel the ship from asteriods, comets, moons, gas giants. If we sent probes ahead we would know that the planet is occupied and might decide not to risk the ship by diverting, since ships really aren't all that tough.

In the best case scenario, this makes sense. But when is it ever the best case?

 

[Onyx]

well, there is another book added to my list.



Maybe, but this is because humanity seems like it is headed for some kind of catastrophe at all times. Whether we are just capable of sending ships into space or ready to colonize, it is a method that works because audiences like it and it seems like a real scenario.



In the best case scenario, this makes sense. But when is it ever the best case?

How is a worst case scenario ship crew going to make a planet habitable for earth life?

 

[night_wrtr]

How is a worst case scenario ship crew going to make a planet habitable for earth life?

That is an excellent writing prompt.

 

[Onyx]

That is an excellent writing prompt.

In the story I'm working on the planet was surveyed and seeded hundreds of years ago and is done terraforming. But the ships also were well stocked when they arrived.

 

[night_wrtr]

In the story I'm working on the planets was surveyed and seeded hundreds of years ago and is done terraforming. But the ships also were well stocked when they arrived.

We can only hope it goes that smoothly!

 

[Onyx]

We can only hope it goes that smoothly!

That part will, because that's just background material to explain why the characters have a virgin world to enact their political machinations upon, rather than being about the difficulty of getting there and making it habitable.

Actually, a story about a crew that spends thousands of years in orbit turning an ice ball into a paradise would be mighty interesting, too. Especially if they can't see spoiling it with people when they're done. I've never seen that, in particular.

 

[J Riff]

There's nothing there. Apparently, the nearest habited place is about 4-5 solar systems away. They have no vacancy though.

 

[Mirannan]

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.

Alpha Centauri B is about 90% of the mass of the Sun and roughly half its luminosity. so it wouldn't be quite as bad as that. In addition, if the planet was in the Goldilocks zone for A, it would also be at least ten times closer to A than B. (The minimum distance between A and B is about 11AU.)

So the gravitational influence of B on an Earth-like planet of A would be a maximum of 1/100 of the main sun's gravity - comparable to solar tides on Earth - and the maximum extra light would be 1/200. Which would make for bright nights, no doubt, when B was at its closest, but I don't really think this would be a problem - especially since, of course, life on a planet of A would have evolved under these conditions.

In the case of a planet of B, IMHO the gravitational situation would be actually less disturbed - because a planet of B would have to be closer to its sun because of the lower luminosity. However, the light of A would then be something like 1/50 that of B at most, which is getting significant - but, again, life would have evolved under those conditions.

 

[Onyx]

Alpha Centauri B is about 90% of the mass of the Sun and roughly half its luminosity. so it wouldn't be quite as bad as that. In addition, if the planet was in the Goldilocks zone for A, it would also be at least ten times closer to A than B. (The minimum distance between A and B is about 11AU.)

So the gravitational influence of B on an Earth-like planet of A would be a maximum of 1/100 of the main sun's gravity - comparable to solar tides on Earth - and the maximum extra light would be 1/200. Which would make for bright nights, no doubt, when B was at its closest, but I don't really think this would be a problem - especially since, of course, life on a planet of A would have evolved under these conditions.

In the case of a planet of B, IMHO the gravitational situation would be actually less disturbed - because a planet of B would have to be closer to its sun because of the lower luminosity. However, the light of A would then be something like 1/50 that of B at most, which is getting significant - but, again, life would have evolved under those conditions.

I guess I was thinking that with the similarity in mass, L1 between the two suns is going to be around 6 AU, and I could see the planet getting tugged toward L1 on every orbit.

And I said 79 years, but it would be closer to 1 year, assuming the planet was in a similar orbit to ours around Alpha. Maybe that oscillation is minor relative to a yearly cycle. I don't know how much it would change the planet's orbit over time, though.