U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > General Forums > Science and Technology > Space
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
Reply Start New Thread
 
Old 07-11-2012, 03:45 AM
 
Location: Wasilla, Alaska
17,825 posts, read 20,498,482 times
Reputation: 6500

Advertisements

Assuming we one day find an Earth-like world around another star. Meaning, a rocky planet that is in the habitable zone of its star, where water is in a liquid state and not gaseous or solid. If I had to guess, based upon the number of exoplanets we are already detecting, it seems very likely that we will find planets meeting this criteria within the next decade.

A planet with liquid water would have to have an atmosphere, but what kind? Earth has had numerous different types of atmospheres over its 4.6 billion year existence. Finding another planet with 78% nitrogen and 21% oxygen would seem extremely unlikely. The possible chemical combinations for an atmosphere seems almost endless. Hydrogen, oxygen, nitrogen, methane, and carbon can be combined into a wide variety of different gases. Then there is the question of atmospheric pressure. Venus has too much, while Mars has too little. Finding an exoplanet with an atmospheric pressure that is anything close to Earth lowers the odds of finding such a planet considerably.

Consider also that if this rocky exoplanet does not have a large enough moon, like Earth, it could "wobble" on its poles. Which means that it could be a frozen wasteland around its equator, and a tropical paradise at its poles, or it would switch back to 90° and completely change the climate again. Our moon keeps Earth relatively stable with a 23.5° axial tilt. Finding such a world also seem unlikely, considering the event that took place to create Earth's moon.

Then there is the rotational speed of the planet. Before the collision with Thea that created the moon, Earth's rotation was around 8 hours. Or, four hour days and four hour nights. Venus has a retrograde rotation, and takes 243 days to rotate once. The chance that we will find a planet with a rotational period even close to Earth's seems remote.

Another benefit Earth gained from the impact with Thea was a much larger iron and nickel core. It is about 1.5 times what it would have been if there had been no impact. Not only did this effect the amount of gravity Earth exerts, but it also is responsible for the tectonic plates and the recycling of materials.

Taking all this into consideration, I seriously doubt we will find another Earth. Or even an exoplanet similar to Earth were we can adapt without artificial means. Therefore, if we accept that it is likely we will need to bring or manufacture our own life-support in order to colonize another world, what would be the point beyond scientific research?

If we cannot adapt to an exoplanet, or adapt the exoplanet to fit our criteria, then it would seem to me that there is no point in sending humans to such a place (beyond pure science of course). The only way we can ensure the survival of the human species is by locating an exoplanet that we can adapt to meet our needs. Perpetually living on a hostile planet, that could kill you the instant you step outside of your artificially protected environment, does not seem to me to be a means to ensure the species survival.

Concerning Mars, I fully support sending a manned-mission to Mars (when we can ensure their safe return), but for scientific purposes, not for colonization.

A Mars colony would have to be completely self-sufficient. They could not rely on regular shipments of technology or equipment from Earth. If a critical component fails, it could take anywhere from six months to two years to reach Mars from Earth. That might be an acceptable risk for a short-term science team, but not for a permanent colony.

I am curious what others might think about this subject. Am I being too pesimistic? Assuming getting to another planet in another solar system was not a problem, what would we do once we got there? Is there another reason to colonize other worlds beyond survival of the species?
Reply With Quote Quick reply to this message

 
Old 07-11-2012, 10:39 AM
 
Location: Somewhere in northern Alabama
18,537 posts, read 55,453,855 times
Reputation: 32256
I agree with you on your assessment of finding another "earth". Even with the "billions and billions", chances of finding anything that is within the window of the planetary life cycle required to support life are slim. BTW, you also left out that the MAJORITY of planets anywhere near a galactic core are out because of much higher radiation, star destructions, and so on.

The support levels required for our bag-o-water bodies are also extremely high. That leaves a couple routes - mining out asteroids and oort cloud objects and using advanced power systems, or evolving our mental "essence" into less demanding containers. When you start examining THAT, you begin to look at ego and what really makes up a mind, and you go hunting for a bottle of scotch.
Reply With Quote Quick reply to this message
 
Old 07-11-2012, 12:34 PM
 
Location: Wasilla, Alaska
17,825 posts, read 20,498,482 times
Reputation: 6500
Quote:
Originally Posted by harry chickpea View Post
I agree with you on your assessment of finding another "earth". Even with the "billions and billions", chances of finding anything that is within the window of the planetary life cycle required to support life are slim. BTW, you also left out that the MAJORITY of planets anywhere near a galactic core are out because of much higher radiation, star destructions, and so on.

The support levels required for our bag-o-water bodies are also extremely high. That leaves a couple routes - mining out asteroids and oort cloud objects and using advanced power systems, or evolving our mental "essence" into less demanding containers. When you start examining THAT, you begin to look at ego and what really makes up a mind, and you go hunting for a bottle of scotch.
I think we will eventually find lots of planets that have life, just not the kinds of planets that will support our life. There was photosynthesis occurring on Earth before the "iron catastrophe." There were periods in Earth's history when CO2 levels were more than a thousand times current levels, yet there was still life. So while I consider life on other planets to be relatively common, I do not think that will prove to be the case in our search to find an environment suitable for the human species.

You are quite right, just as there is a habitable zone around every star, there is also a habitable zone for our galaxy. The closer you are to the galactic center the denser the stars, and the greater the radiation. The same is also true for the spiral arms, where the bulk of the stars in the galaxy form. There is also a 60% chance that when we do find a rocky type exoplanet in a habitable zone it will be in a binary system, and could be circling one, or both, of the stars.

I think finding an exoplanet that is close enough to meet our needs is possible, just not probable. I think other Earth's are incredibly rare. So I guess the real question becomes, "How far are we willing to adapt in order to become suited for other environments?" Are they willing to make biological changes in order to adapt to a different environment, and assuming they do, would they still be considered "human" if they could no longer live on Earth?
Reply With Quote Quick reply to this message
 
Old 07-12-2012, 12:38 PM
 
5,203 posts, read 8,207,066 times
Reputation: 3188
Quote:
Originally Posted by Glitch View Post
I think we will eventually find lots of planets that have life, just not the kinds of planets that will support our life. There was photosynthesis occurring on Earth before the "iron catastrophe." There were periods in Earth's history when CO2 levels were more than a thousand times current levels, yet there was still life. So while I consider life on other planets to be relatively common, I do not think that will prove to be the case in our search to find an environment suitable for the human species.

You are quite right, just as there is a habitable zone around every star, there is also a habitable zone for our galaxy. The closer you are to the galactic center the denser the stars, and the greater the radiation. The same is also true for the spiral arms, where the bulk of the stars in the galaxy form. There is also a 60% chance that when we do find a rocky type exoplanet in a habitable zone it will be in a binary system, and could be circling one, or both, of the stars.

I think finding an exoplanet that is close enough to meet our needs is possible, just not probable. I think other Earth's are incredibly rare. So I guess the real question becomes, "How far are we willing to adapt in order to become suited for other environments?" Are they willing to make biological changes in order to adapt to a different environment, and assuming they do, would they still be considered "human" if they could no longer live on Earth?
I'd agree that there's a much higher likelihood for microbial life forms on most rocky planets within a habitable zone from its parent star. Intelligent life, and especially life high techologies, is probably rare. There could be loads of suitable exoplanets scattered around the universe. But if they're located in other galaxies, it's not likely anyone from Earth will be migrating there. Even if we found a suitable planet within our own galaxy, it may be so distant that it would very unlikely to travel there. I'm not all that optimistic we'll find anything suitable that's reasonably close in terms of interstellar travel though.

There may be rocky exoplanets orbiting two stars. The problem is that the orbit of such a planet would probably be a huge distance from either star, perhaps bringing it in close enough, assuming the best of conditions, to be considered habitable for part of the time, and completely frozen at other times. It's more likely for a habitable planet in a binary system if the stars are greatly from one another and the planet is orbiting just one of them. Up to now, most of the exoplanets in habitable zones seem to be gas giants that are generally larger than Jupiter. Even at that, the usual means of detection is either by planets transiting a star, or from the wobble of a star indicating gravitational tugging.

I also agree that it's not too likely we'll be seeing much of any migration to planets or moons within our own solar system. It's possible Mars could be terreformed, but even so, it could be talking about thousands of years, if not tens of thousands. That pretty much leaves it as a potential scientific station and the occasional space tourist with money to burn.

If we ever reach a point when people in large numbers could permanently leave the Earth, I'd say huge nomadic multi-generational spacecrafts that contain their own ecosystem would be a more practical option. Except perhaps for a short time for study or to extract certain resources if necessary, there would really be a need to colonize an exoplanet planet?
Reply With Quote Quick reply to this message
 
Old 07-13-2012, 12:14 AM
 
Location: Wasilla, Alaska
17,825 posts, read 20,498,482 times
Reputation: 6500
Quote:
Originally Posted by NightBazaar View Post
I'd agree that there's a much higher likelihood for microbial life forms on most rocky planets within a habitable zone from its parent star. Intelligent life, and especially life high techologies, is probably rare.
I was not even contemplating intelligent life. I was thinking of merely complex life (think Cambrian). Something beyond microorganisms and algae. However, I agree that microbial life should be relatively common for rocky planets within a habitable zone from its parent's star. The Earth experienced over three billion years of microbial life before the "Cambrian explosion." This is the state I would expect most of the exoplanets that we find capable of sustaining life to be in; no complex plants, no animals, no insects, just microorganisms.

Quote:
Originally Posted by NightBazaar View Post
There could be loads of suitable exoplanets scattered around the universe. But if they're located in other galaxies, it's not likely anyone from Earth will be migrating there. Even if we found a suitable planet within our own galaxy, it may be so distant that it would very unlikely to travel there. I'm not all that optimistic we'll find anything suitable that's reasonably close in terms of interstellar travel though.
Most people focus on getting there, I am ignoring that aspect for the time being and trying to understand the purpose for going. Is there another reason beyond scientific research? How realistic is it to set up a permanent colony on another exoplanet if we have to permanently rely on life-support and protected environments?

Getting there is just a matter of physics and technology, but what would we do once we get there? Beyond scientific research, what is the point of going?

Quote:
Originally Posted by NightBazaar View Post
There may be rocky exoplanets orbiting two stars. The problem is that the orbit of such a planet would probably be a huge distance from either star, perhaps bringing it in close enough, assuming the best of conditions, to be considered habitable for part of the time, and completely frozen at other times. It's more likely for a habitable planet in a binary system if the stars are greatly from one another and the planet is orbiting just one of them. Up to now, most of the exoplanets in habitable zones seem to be gas giants that are generally larger than Jupiter. Even at that, the usual means of detection is either by planets transiting a star, or from the wobble of a star indicating gravitational tugging.
That depends on the orbit of the binary system. If you have two stars in a very close orbit, a planet could be orbiting the barycenter of both stars. However, in a binary system like Alpha Centauri planets could orbit each star, but not both. Alpha Centauri B's orbit comes within Saturn's orbit of Alpha Cenaruri A at its closest point, and as far as Pluto is from the Sun at its furthest point. Also, the habitable zone of Alpha Centauri A is closer than ours since it is 90% of the mass of the Sun and 50% dimmer. Both Alpha Centauri A & B also have a higher level of metalicity than our Sun. Which means that rocky planets are possible around Alpha Centauri A. However, considering the close orbit of both A & B, it is highly unlikely that there would be any gas giants. They would have to be very close to their parent star, and we would have detected their wobble or transit by now. Detecting rocky type planets in the Alpha Centauri system would also prove to be problematic considering both stars are gravitationally tugging on each other. Making the tug of small rocky planets virtually undetectable.

Quote:
Originally Posted by NightBazaar View Post
I also agree that it's not too likely we'll be seeing much of any migration to planets or moons within our own solar system. It's possible Mars could be terreformed, but even so, it could be talking about thousands of years, if not tens of thousands. That pretty much leaves it as a potential scientific station and the occasional space tourist with money to burn.
I am certain we could speed up the process of terraforming Mars with a few well placed comets and asteroids from the Asteroid Belt. Even still, we are talking about a very long time before the atmosphere becomes less toxic and with enough atmospheric pressure to keep our blood from turning into a gaseous state the instant we walk out the door. Without a strong magnetosphere like Earth, the solar winds will continue to strip off the atmosphere like it already has. Not to mention virtually no protection from solar radiation. No matter how you slice it, if we ever do live on Mars we will always need artificial protection from the environment. We could never turn Mars into an Earth-like planet.

Quote:
Originally Posted by NightBazaar View Post
If we ever reach a point when people in large numbers could permanently leave the Earth, I'd say huge nomadic multi-generational spacecrafts that contain their own ecosystem would be a more practical option. Except perhaps for a short time for study or to extract certain resources if necessary, there would really be a need to colonize an exoplanet planet?
I can see us one day working in space. Much like those who work on the North Slope in Alaska. They fly up for a couple weeks, do their jobs, then fly home for a couple weeks. Nobody lives there permanently, except the native Alaskans who lived there before we discovered oil in Prudhoe Bay.

I am coming to the conclusion that space will be a place for science and eventually employment, but not colonization. Or rather, I can come up with no rational explanation as to why we would colonize another planet on a permanent basis.
Reply With Quote Quick reply to this message
 
Old 07-13-2012, 10:49 AM
 
5,203 posts, read 8,207,066 times
Reputation: 3188
Quote:
Originally Posted by Glitch View Post
I was not even contemplating intelligent life. I was thinking of merely complex life (think Cambrian). Something beyond microorganisms and algae. However, I agree that microbial life should be relatively common for rocky planets within a habitable zone from its parent's star. The Earth experienced over three billion years of microbial life before the "Cambrian explosion." This is the state I would expect most of the exoplanets that we find capable of sustaining life to be in; no complex plants, no animals, no insects, just microorganisms.
I was more thinking out loud about it because it's one of the big questions we have about life. Are we alone? We naturally wonder about whether or not we're the only form of intelligent life. The general consensus leans toward the idea that it's pretty hard to think we're the only ones in the universe, for that matter the galaxy. But I'm inclined to think it's extremely rare. But then who knows? Intelligent life could be a lot more common than we think. At the moment though, I'm not that optimistic.

I agree that the most abundant form of life is likely to be microbial. Just on Earth alone, there are more microbes living right now than there has ever been of complex organisms in the entire history of Earth. Still, depending on how long life has existed on an habitable planet, it could evolve into complex biological and botanical life. It just depends on whether or not the overall conditions of the planet itself has changed enough over time to give organisms the chance to evolve. If there's water, along with other conditions, there's a chance for life. In our own solar system, some of the icy-layered moons are thought to contain oceans that could be possible for life, even complex forms to exist there, although there's no way of knowing apart from sinking a submersible probe to have a look.




Quote:
Most people focus on getting there, I am ignoring that aspect for the time being and trying to understand the purpose for going. Is there another reason beyond scientific research? How realistic is it to set up a permanent colony on another exoplanet if we have to permanently rely on life-support and protected environments?


Getting there is just a matter of physics and technology, but what would we do once we get there? Beyond scientific research, what is the point of going?
The only other purpose for setting up a colony on another planet, is the idea that the Earth can sustain only so much, not to mention that it still remains possible that a good-sized asteroid, or especially a comet, could eventually collide with results of causing the extinction of the human race, and perhaps most other life on the planet. What was observed when Schumaker-Levi hit Jupiter was not only an impressive event to witness, but kind of serves as a wake up call that the Earth is not immune from such a catastrophe, but then Mars is also a potential target. I think we have the potential to eventually avoid such a risk to our species if we can ever manage to migrate off the planet enough to spread ourselves around which would increase the odds for longer survival of the human race.

As for it being just a matter of physics and technology, that often assumes its inevitable, is that it easily rolls off the tongue because we take so many things for granted. We'll probably reach that point of technology, but since we're still far from it, all we can do is speculate about it. There are a lot of events that can happen to prevent us from developing technologies that would allow interstellar travel seem like a walk in the park. It's happened before in history, such as the Dark Ages Unfortunately, it coulld happen again. We are currently so dependent on technology, that if the power and communications grid were to suffer a catastrophic faliure, we'd be plunged back to surviving without it. We'd probably see a massive drop in the global population. One of the problems of rapid advancement is that we're not always able to accurately foresee all future risks or threats that we can avoid.





Quote:
That depends on the orbit of the binary system. If you have two stars in a very close orbit, a planet could be orbiting the barycenter of both stars. However, in a binary system like Alpha Centauri planets could orbit each star, but not both. Alpha Centauri B's orbit comes within Saturn's orbit of Alpha Cenaruri A at its closest point, and as far as Pluto is from the Sun at its furthest point. Also, the habitable zone of Alpha Centauri A is closer than ours since it is 90% of the mass of the Sun and 50% dimmer. Both Alpha Centauri A & B also have a higher level of metalicity than our Sun. Which means that rocky planets are possible around Alpha Centauri A. However, considering the close orbit of both A & B, it is highly unlikely that there would be any gas giants. They would have to be very close to their parent star, and we would have detected their wobble or transit by now. Detecting rocky type planets in the Alpha Centauri system would also prove to be problematic considering both stars are gravitationally tugging on each other. Making the tug of small rocky planets virtually undetectable.
I'm not saying rocky planets can't exist in a binary system, but if life emerges with conditions similar to Earth, it might not emerge at all in a binary star system. That is, in terms of the planet orbiting both stars. If the stars are separated far enough, it's possible if the planet orbits one star or the other that life could possibly emerge. If a planet orbits 90 degrees to the accretion disk, life could emerge. But if the planet orbits in such an accretion disk with twin stars at the center, then twice each orbit, the planet will go through seasons of extreme heat and extreme cold. While it might average out as habitable, it would probably not be a planet one would feel comfortable living on. We don't have any other known model for the conditions of life, other than that of our own planet. Of course, it life can emerge under exotic conditions, then all bets are off and life could emerge wherever it wants.





Quote:
I am certain we could speed up the process of terraforming Mars with a few well placed comets and asteroids from the Asteroid Belt. Even still, we are talking about a very long time before the atmosphere becomes less toxic and with enough atmospheric pressure to keep our blood from turning into a gaseous state the instant we walk out the door. Without a strong magnetosphere like Earth, the solar winds will continue to strip off the atmosphere like it already has. Not to mention virtually no protection from solar radiation. No matter how you slice it, if we ever do live on Mars we will always need artificial protection from the environment. We could never turn Mars into an Earth-like planet.
One thought that has been proposed to make Mars at least somewhat habitable is to pollute the atmosphere. The idea is that it could warm up the planet enough for water to take on a liquid state. There are some indications that liquid water might periodically emerge to the surface from underground. Other suggestions are to go underground in caves, which would be more likely to serve as protection from solar radiation. Habitats could work out be above ground by covering it with a thick layer of rock, but that's be like living in a cave anyway. There's no question in my mind that to adapt to such an environment, living structures would have to be designed for it. Exactly how enough food could be grown to sustain a viable and growing population on Mars is hard to guess.





Quote:
I can see us one day working in space. Much like those who work on the North Slope in Alaska. They fly up for a couple weeks, do their jobs, then fly home for a couple weeks. Nobody lives there permanently, except the native Alaskans who lived there before we discovered oil in Prudhoe Bay.
I also think that space, for the most part, at least in the foreseeable future, is going to remain limited to periodically work, mostly to extract resources. I'm not sure the North Slope of Alaska is a good argument because native Alaskans have and do live there. Perhaps a better example would be Antartica, where there are no permanent settlements. Because of international treaties, I'm not sure there ever would be, unless there were major changes in the treaties. The same thing applies to space. There are international agreements that no one owns celestial objects beyond the Earth. The Moon is supposedly covered by that, and yet, NASA has raised warnings that the sites of the lunar landings are to remain off limits to anyone going to the Moon, the claim being that they are historical relics. Other concerns have been raised regarding the asteroids. If someone sends a team to mine various asteroids, who owns them?
Who Owns The Asteroids? : Discovery News



Quote:
I am coming to the conclusion that space will be a place for science and eventually employment, but not colonization. Or rather, I can come up with no rational explanation as to why we would colonize another planet on a permanent basis.
I think colonization could be possible, but if we are ever to leave the entire solar system, the crafts needed for a migration (not that everyone would), would have to be able to sustain those onboard, unless some sort of long term hibernation is feasible. Even at that, if we had the technology to send large numbers of people into space, I'd still say a multigenerational craft would be a good option, sort of like a having a small mobile planet. If such a craft could be designed to support and sustain life, then would there really be a need to colonize a habitable exoplanet (although some might want to) if we can adapt to life on such a craft?

Among some of the big questions about how feasible such migration is how dependent and connected are we to the Earth's ecosystem? For example, we have a symbiotic relationship with microbes. Can we adapt without them? We have around 200 or so different kinds of bacteria in our gut. That's not counting those that live on the skin and elsewhere in the body. As it is, we have no idea just how many different kinds of microbes there are on Earth. There are a number of things to better understand the nature of before we can confidently say we can traipse off to colonize other planets whenever we feel like it. We still have a lot of things to learn about the Earth and life on Earth.
Reply With Quote Quick reply to this message
 
Old 07-13-2012, 02:25 PM
 
Location: Wasilla, Alaska
17,825 posts, read 20,498,482 times
Reputation: 6500
Quote:
Originally Posted by NightBazaar View Post
I was more thinking out loud about it because it's one of the big questions we have about life. Are we alone? We naturally wonder about whether or not we're the only form of intelligent life. The general consensus leans toward the idea that it's pretty hard to think we're the only ones in the universe, for that matter the galaxy. But I'm inclined to think it's extremely rare. But then who knows? Intelligent life could be a lot more common than we think. At the moment though, I'm not that optimistic.
Thinking out loud is good, that is what this thread is about.

I think intelligent life is possible, under the right conditions, but I am also inclined to think it is extremely rare. The universe is a very violent place, and we have been very lucky for a long time. Also, I think two or more intelligent life-forms existing at the same time in the same relative proximity is highly improbable.

Quote:
Originally Posted by NightBazaar View Post
I agree that the most abundant form of life is likely to be microbial. Just on Earth alone, there are more microbes living right now than there has ever been of complex organisms in the entire history of Earth. Still, depending on how long life has existed on an habitable planet, it could evolve into complex biological and botanical life. It just depends on whether or not the overall conditions of the planet itself has changed enough over time to give organisms the chance to evolve. If there's water, along with other conditions, there's a chance for life. In our own solar system, some of the icy-layered moons are thought to contain oceans that could be possible for life, even complex forms to exist there, although there's no way of knowing apart from sinking a submersible probe to have a look.
If we find green algae under that ice, that is okay, but if we find "pink slime" then it means WAR!

I think life is more common than we think. Even where we did not think it was possible, I expect that we may find life. Too often our assumptions based upon our own experiences have been proven wrong. Like gas giants orbiting their stars so closely it only takes days instead of decades. We still have no good explanation how a gas giant the size of Jupiter could have formed or have been captured in so close an orbit.

"There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy." -- William Shakespeare, Hamlet: Act I, Scene V.

Quote:
Originally Posted by NightBazaar View Post
The only other purpose for setting up a colony on another planet, is the idea that the Earth can sustain only so much, not to mention that it still remains possible that a good-sized asteroid, or especially a comet, could eventually collide with results of causing the extinction of the human race, and perhaps most other life on the planet. What was observed when Schumaker-Levi hit Jupiter was not only an impressive event to witness, but kind of serves as a wake up call that the Earth is not immune from such a catastrophe, but then Mars is also a potential target. I think we have the potential to eventually avoid such a risk to our species if we can ever manage to migrate off the planet enough to spread ourselves around which would increase the odds for longer survival of the human race.
I think overpopulation or resource depletion is a poor excuse for colonization. We could never send more people into space than are being born, and we would be better served using our technological resources to obtain more or different resources rather than colonizing space. Mining asteroids for essential resources seems plausible, but it does not make sense to establish a permanent colony for such purposes.

The possibility of a large asteroid or comet impacting Earth always exists, but that is mitigated by our ability to track such objects and our technological ability to alter its course. Thus negating the threat. This seems to be the biggest threat to Earth, with regard to mass extinctions. The Permian, Triassic, and Cretaceous extinction events were all thought to have been caused by large asteroids or comets. There is certainly good evidence to support those claims.

Having said all that, there is wisdom in not putting all your eggs in one basket.

Quote:
Originally Posted by NightBazaar View Post
As for it being just a matter of physics and technology, that often assumes its inevitable, is that it easily rolls off the tongue because we take so many things for granted. We'll probably reach that point of technology, but since we're still far from it, all we can do is speculate about it. There are a lot of events that can happen to prevent us from developing technologies that would allow interstellar travel seem like a walk in the park. It's happened before in history, such as the Dark Ages Unfortunately, it coulld happen again. We are currently so dependent on technology, that if the power and communications grid were to suffer a catastrophic faliure, we'd be plunged back to surviving without it. We'd probably see a massive drop in the global population. One of the problems of rapid advancement is that we're not always able to accurately foresee all future risks or threats that we can avoid.
I am not assuming or taking anything for granted, I am focusing on a particular aspect of space colonization. In most discussions I have had concerning colonization the focus has been on our ability to get there. I started this thread to focus primarily on the purpose for going in the first place, and not concern ourselves with how to get there. I will save that for a different thread.

With regard to major civilization destroying disasters, like say a world-wide pandemic, a space colony could be used as a repository for our current knowledge. Like a modern day version of the Great Library at Alexandria. I think that is a great idea. I had not thought of that before.

Quote:
Originally Posted by NightBazaar View Post
I'm not saying rocky planets can't exist in a binary system, but if life emerges with conditions similar to Earth, it might not emerge at all in a binary star system. That is, in terms of the planet orbiting both stars. If the stars are separated far enough, it's possible if the planet orbits one star or the other that life could possibly emerge. If a planet orbits 90 degrees to the accretion disk, life could emerge. But if the planet orbits in such an accretion disk with twin stars at the center, then twice each orbit, the planet will go through seasons of extreme heat and extreme cold. While it might average out as habitable, it would probably not be a planet one would feel comfortable living on. We don't have any other known model for the conditions of life, other than that of our own planet. Of course, it life can emerge under exotic conditions, then all bets are off and life could emerge wherever it wants.
Since the habitable zone around our Sun is somewhere greater than 0.5 AUs and less than 1.5 AUs. The habitable zone would have to be a little closer to Alpha Centauri A, and much closer to Alpha Centauri B, considering the size and luminosity of both stars. That would still leave a gap of at least 7 AUs between stars at their closest point in their orbits. So I think it is very possible for rocky type planets to be in orbit around both Alpha Centauri A and/or B, just not around both stars.

I also think that if there are rocky planets found around either Alpha Centauri A or B, they will have the same eccentric orbit as their parent star and be in the same plane. Which means that according to B's apparent trajectory, depicted below, any planet would not transit its star from our visible angle. Further complicating the detection of planets within the system.



Quote:
Originally Posted by NightBazaar View Post
One thought that has been proposed to make Mars at least somewhat habitable is to pollute the atmosphere. The idea is that it could warm up the planet enough for water to take on a liquid state. There are some indications that liquid water might periodically emerge to the surface from underground. Other suggestions are to go underground in caves, which would be more likely to serve as protection from solar radiation. Habitats could work out be above ground by covering it with a thick layer of rock, but that's be like living in a cave anyway. There's no question in my mind that to adapt to such an environment, living structures would have to be designed for it. Exactly how enough food could be grown to sustain a viable and growing population on Mars is hard to guess.
I read about that. Building factories near the pole where it can separate the CO2 into both carbon and oxygen. We keep the oxygen for our habitats and fuel, and use the carbon for other purpose or pump it into the atmosphere in an effort to increase greenhouse gases. One question: Could those factories pump out enough CO2 into the atmosphere to make a difference, or will the solar winds rip it from the planet faster than we can produce it?

Underground structures would seem to be the safest form of habitation on Mars. Separate artificial environments for plants and humans could be easily maintained. In fact, the environment could be specifically tailored for plants by increasing CO2 levels in the atmosphere, and growing them under lights for 20 hours until they are ready to bear fruit, then reduce the lights to 12 hours. They will produce more and grow bigger than they normally would on Earth. Especially in a less than 1G environment.

Quote:
Originally Posted by NightBazaar View Post
I also think that space, for the most part, at least in the foreseeable future, is going to remain limited to periodically work, mostly to extract resources. I'm not sure the North Slope of Alaska is a good argument because native Alaskans have and do live there. Perhaps a better example would be Antartica, where there are no permanent settlements. Because of international treaties, I'm not sure there ever would be, unless there were major changes in the treaties. The same thing applies to space. There are international agreements that no one owns celestial objects beyond the Earth. The Moon is supposedly covered by that, and yet, NASA has raised warnings that the sites of the lunar landings are to remain off limits to anyone going to the Moon, the claim being that they are historical relics. Other concerns have been raised regarding the asteroids. If someone sends a team to mine various asteroids, who owns them?
Who Owns The Asteroids? : Discovery News
I tend to agree and space, in the foreseeable future, will be the realm of science and employment, but not colonization.

I also agree with NASA's warnings. I would feel the same way if the Russians had beaten us to the Moon. The very first manned lunar landing must be preserved as an historic relic. The very first time humans walked on another world should be, nay, MUST be preserved.

The ownership of asteroids is a very interesting, and complex, question. I will have to give it some thought.

Quote:
Originally Posted by NightBazaar View Post
I think colonization could be possible, but if we are ever to leave the entire solar system, the crafts needed for a migration (not that everyone would), would have to be able to sustain those onboard, unless some sort of long term hibernation is feasible. Even at that, if we had the technology to send large numbers of people into space, I'd still say a multigenerational craft would be a good option, sort of like a having a small mobile planet. If such a craft could be designed to support and sustain life, then would there really be a need to colonize a habitable exoplanet (although some might want to) if we can adapt to life on such a craft?

Among some of the big questions about how feasible such migration is how dependent and connected are we to the Earth's ecosystem? For example, we have a symbiotic relationship with microbes. Can we adapt without them? We have around 200 or so different kinds of bacteria in our gut. That's not counting those that live on the skin and elsewhere in the body. As it is, we have no idea just how many different kinds of microbes there are on Earth. There are a number of things to better understand the nature of before we can confidently say we can traipse off to colonize other planets whenever we feel like it. We still have a lot of things to learn about the Earth and life on Earth.
I think we can pretty much rule out hibernation, unless we can invent a "Stasis Chamber" like in a lot of SciFi shows. Humans do not freeze well, we tend to get "freezer-burn" rather quickly.

I think no matter where we go we will be bringing our microbes with us. Will our microbes interact with alien microbes and create a virulent and deadly strain of microbes? If we ever do discover alien life, we are going to have to very careful how we interact with that life. Contamination in either direction could prove catastrophic.
Reply With Quote Quick reply to this message
 
Old 07-14-2012, 12:34 AM
 
5,203 posts, read 8,207,066 times
Reputation: 3188
Quote:
Originally Posted by Glitch View Post
Thinking out loud is good, that is what this thread is about.

I think intelligent life is possible, under the right conditions, but I am also inclined to think it is extremely rare. The universe is a very violent place, and we have been very lucky for a long time. Also, I think two or more intelligent life-forms existing at the same time in the same relative proximity is highly improbable.
I think we pretty well agree that the likelihood of of intelligent life forms is probably rare. I'm doubtful there are any in the stellar neighborhood, although there could be several scattered around the rest of the galaxy.

Quote:
If we find green algae under that ice, that is okay, but if we find "pink slime" then it means WAR!

I think life is more common than we think. Even where we did not think it was possible, I expect that we may find life. Too often our assumptions based upon our own experiences have been proven wrong. Like gas giants orbiting their stars so closely it only takes days instead of decades. We still have no good explanation how a gas giant the size of Jupiter could have formed or have been captured in so close an orbit.


"There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy." -- William Shakespeare, Hamlet: Act I, Scene V.
Hmm, pink slime? Like the Blob?

Quote:
I think overpopulation or resource depletion is a poor excuse for colonization. We could never send more people into space than are being born, and we would be better served using our technological resources to obtain more or different resources rather than colonizing space. Mining asteroids for essential resources seems plausible, but it does not make sense to establish a permanent colony for such purposes.

The possibility of a large asteroid or comet impacting Earth always exists, but that is mitigated by our ability to track such objects and our technological ability to alter its course. Thus negating the threat. This seems to be the biggest threat to Earth, with regard to mass extinctions. The Permian, Triassic, and Cretaceous extinction events were all thought to have been caused by large asteroids or comets. There is certainly good evidence to support those claims.

Having said all that, there is wisdom in not putting all your eggs in one basket.
Somehow, if an asteroid or comet the size of the those that have hit Jupiter were to hit the Earth, I suspect there wouldn't be much we could do about it, regardless of tracking capability. The only option would be to get out of the way, and that isn't an option for us right now. Some of the largest impacts from Comet Shoemaker-Levy on Jupiter were estimated to be at least 1 km in size. Another one, thought to be a rogue asteroid smacked into the planet in July 2009. The impact scar was as large as the Pacific Ocean. An object of that magnitude could easily wipe out most, if not all life on Earth.
Comet Shoemaker-Levy 9 Fragment Size Estimates: How Big was the Parent Body?

Rogue Asteroid, Not Comet, Smacked Into Jupiter | Space.com

Quote:
I am not assuming or taking anything for granted, I am focusing on a particular aspect of space colonization. In most discussions I have had concerning colonization the focus has been on our ability to get there. I started this thread to focus primarily on the purpose for going in the first place, and not concern ourselves with how to get there. I will save that for a different thread.

With regard to major civilization destroying disasters, like say a world-wide pandemic, a space colony could be used as a repository for our current knowledge. Like a modern day version of the Great Library at Alexandria. I think that is a great idea. I had not thought of that before.
I know you weren't making the assumption, but there are plenty of people who do indeed only focus on getting there. Getting there is only part of such an endeavor. Certainly part of the purpose is to see if it is possible for people to survive. We've been to the Moon, and that's still the record distance from Earth. We have no idea how well a long-term mission would work. There are a lot of hurtles to overcome, especially weighlessness and deep space radiation.

As far as I'm concerned, the only other potentially habitable planet in the solar system is probably Mars. Everything else would be for either scientific or industrial missions. It's hard to guess about potentially habitable planets around other stars. We'd need to know what the atmosphere is like, and whether or not there is any life there. We'd need to know the composition of any land masses and how much water is there. If it can be terraformed, then I think it could ultimately become a potential destination for migration. We don't have the ability to see such rocky exoplanets, but we might develop a way to actually see them in the future, although we still won't see much in the way of surface details. But the view could be as good as those from Hubble looking at Pluto. Pretty blurry, but you can see some features.

Quote:
Since the habitable zone around our Sun is somewhere greater than 0.5 AUs and less than 1.5 AUs. The habitable zone would have to be a little closer to Alpha Centauri A, and much closer to Alpha Centauri B, considering the size and luminosity of both stars. That would still leave a gap of at least 7 AUs between stars at their closest point in their orbits. So I think it is very possible for rocky type planets to be in orbit around both Alpha Centauri A and/or B, just not around both stars.

I also think that if there are rocky planets found around either Alpha Centauri A or B, they will have the same eccentric orbit as their parent star and be in the same plane. Which means that according to B's apparent trajectory, depicted below, any planet would not transit its star from our visible angle. Further complicating the detection of planets within the system.
I see what you're saying. Sure, each star could have a rocky planet in the habitable zone for those stars.

Quote:
I read about that. Building factories near the pole where it can separate the CO2 into both carbon and oxygen. We keep the oxygen for our habitats and fuel, and use the carbon for other purpose or pump it into the atmosphere in an effort to increase greenhouse gases. One question: Could those factories pump out enough CO2 into the atmosphere to make a difference, or will the solar winds rip it from the planet faster than we can produce it?

Underground structures would seem to be the safest form of habitation on Mars. Separate artificial environments for plants and humans could be easily maintained. In fact, the environment could be specifically tailored for plants by increasing CO2 levels in the atmosphere, and growing them under lights for 20 hours until they are ready to bear fruit, then reduce the lights to 12 hours. They will produce more and grow bigger than they normally would on Earth. Especially in a less than 1G environment.

I tend to agree and space, in the foreseeable future, will be the realm of science and employment, but not colonization.
My understanding is that pollution of the atmosphere would pretty much be an ongoing thing. There's no significant magnetic field to protect the atmosphere. How long it would take for solar winds to blow off the atmosphere is hard to say. Mars does have an atmosphere though, albeit very weak. I think that the ideas of terraforming Mars to where it would eventually have a viable ecosystem suitable for human beings is pretty much a fantasy. People would have to live in enclosed habitats.

One thing about growing plants, especially for food, is that they require specific nutrients, regardless of whether grown in the soil or hydroponically. I'm not sure if such nutrients are available on Mars or not. The surface certainly wouldn't work for crops. We'd need to look deeper below the surface and do a soil analysis. The next generation of rovers to Mars is expected to be able to dig down a few meters deep.

Quote:
I also agree with NASA's warnings. I would feel the same way if the Russians had beaten us to the Moon. The very first manned lunar landing must be preserved as an historic relic. The very first time humans walked on another world should be, nay, MUST be preserved.

The ownership of asteroids is a very interesting, and complex, question. I will have to give it some thought.
I can see NASA's concerns as well, however, the Moon is supposedly under a treaty that the Moon is for all people, not a possession of governments. It's a bit of a sticky problem. What if there are valuable and easy to get at resources at those landing sites?

Quote:
I think we can pretty much rule out hibernation, unless we can invent a "Stasis Chamber" like in a lot of SciFi shows. Humans do not freeze well, we tend to get "freezer-burn" rather quickly.

I think no matter where we go we will be bringing our microbes with us. Will our microbes interact with alien microbes and create a virulent and deadly strain of microbes? If we ever do discover alien life, we are going to have to very careful how we interact with that life. Contamination in either direction could prove catastrophic.
I wasn't thinking about crygenics when I said hibernation, but rather as deep sleep and slower metabolism. "Stasis chamber" is a better term though. The design of those in the movie Alien looked pretty clever.

Sure, we'll bring along microbes, but I think there's more to it in terms of developing a long-term self-sufficient ecosystem. The Earth's ecosystem is pretty complex. There have been large experiments with an enclosed ecosystem, but hard to determine for long term applications. Biosphere 2 failed in the first mission. The second mission sort of successful, but was briefly sabatoged. I don't know how well it would would in space or another planet. At least on Earth, if something goes wrong, the subjects can escape. Can't do that in space. I think more research needs to be made.
Biosphere 2 - Wikipedia, the free encyclopedia

Biosphere 2 The Experiment
Reply With Quote Quick reply to this message
 
Old 07-19-2012, 12:06 AM
 
Location: Texas
1,770 posts, read 2,047,406 times
Reputation: 618
Quote:
Originally Posted by Glitch View Post

I think intelligent life is possible, under the right conditions, but I am also inclined to think it is extremely rare. The universe is a very violent place, and we have been very lucky for a long time. Also, I think two or more intelligent life-forms existing at the same time in the same relative proximity is highly improbable.


A few years ago my [NASA scientist] relative sent me this SETI article.

You might find it interesting.

Oddly, he sent it to me as a response to my question about Comet Holmes
flaring while at Perseus' arm. He said to note the second half of the article.



"... there's another property of the universe that's equally noteworthy: It's set up in a way that keeps everyone isolated. "


Aliens Apart | Space.com



.
Reply With Quote Quick reply to this message
 
Old 07-23-2012, 12:13 PM
 
Location: Wasilla, Alaska
17,825 posts, read 20,498,482 times
Reputation: 6500
Quote:
Originally Posted by king's highway View Post
A few years ago my [NASA scientist] relative sent me this SETI article.

You might find it interesting.

Oddly, he sent it to me as a response to my question about Comet Holmes
flaring while at Perseus' arm. He said to note the second half of the article.



"... there's another property of the universe that's equally noteworthy: It's set up in a way that keeps everyone isolated. "


Aliens Apart | Space.com



.
I do not think anything is "set up" in any particular way. I think that the universe is an incredibly violent place and it is extremely rare when life has more than three billion years of relative peace and quiet in order to evolve. It has only been 542 million years since complex life forms first evolved on Earth. That is just over two rotations around the Milky Way galaxy out of the 18+ rotations our solar system has already made since its formation. We also have the good fortune to be between two spiral arms and two-thirds away from the galactic center where the density of stars are fewer.

I think there are a great many exoplanets, and a few of those will be within the habitable zone of their star. I also think that on such planets we are likely to find microbial life forms. There could have been at least 9 billion years where other planets like Earth could have formed and produced complex life before Earth ever formed. So the odds of finding other intelligent life living at the same time as us, in relatively the same location, I find highly improbable.

I think it is far more likely that we will find other planets that are more similar to either Venus or Mars than Earth. When we do find other Earth's, I think we are likely to find either microbial life, or life that has become extinct because of some space disaster millions or billions of years before we existed.
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:

Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > General Forums > Science and Technology > Space
Follow City-Data.com founder on our Forum or

All times are GMT -6.

© 2005-2019, Advameg, Inc. · Please obey Forum Rules · Terms of Use and Privacy Policy · Bug Bounty

City-Data.com - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 - Top