The search for earthlike planets

It looks highly likely that we will be able to find an earthlike planet within 20 years thanks to new telescope technology:

http://www.space.com/scienceastronom...od-100414.html

A new space-based telescope using the technology should be able to detect an earthlike planet within 30 light years of earth.

If we find earth like planets, it is imperative to the long-term survival of the human race that we settle them. However, it's unlikely that such a project could ever get off the ground until a high-tech, post-capitalist, post-scarcity society (communist technocracy) is established on Earth.

I see the settling of other Earth like planets as something that will come after technocratic communism has replaced capitalism. The initial return on investment is way too long for such a project to work under a capitalist framework. Capitalism will not take us outside the solar system.

The thing is, even if we do find an Earth-like planet in the near future, it will be a stupendous distance away, and I don't think we can afford to wait that long.

While I am confident that we will have the technical ability to create a "home from home" elsewhere in the Sol system (Whether through pressurised colonies on other worlds, space habitats, or para/terraforming), I think there are inherent human limitations that will make the job more difficult and resource intensive.

Hence I also advocate that we extend those limits. If we could live comfortably in microgravity, or at lower/higher atmospheric pressures, with higher radiation resistance, or whatever would serve to reduce the amount of environmental tinkering, then such parahumans would be better adapted at living in environments we simply did not evolve to cope with. For example, the ability to survive for longer in the vacuum of space would be a boon for the residents of any space habitat in the event of an accident.

The thing is, even if we do find an Earth-like planet in the near future, it will be a stupendous distance away, and I don't think we can afford to wait that long.

I like to think of the interstellar ark as a self-sufficient space colony that is also capable of movement. It should be designed so that humans can live there for hundreds to thousands of years. So, just by building it you have a new place for people to live, which will eventually carry them to a habitable world.

One of the proposed Orion ship designs weighed 8 million tons - essentially an entire city and all its support facilities.

I like to think of the interstellar ark as a self-sufficient space colony that is also capable of movement. It should be designed so that humans can live there for hundreds to thousands of years. So, just by building it you have a new place for people to live, which will eventually carry them to a habitable world.

Interstellar arks are all well and good, but we still need to have a complex infrastructure in place in the Solar system in order to construct just one such vessel, which would be a massive project. Not only that, but we would need considerable practical experience in constructing and maintaining self-sufficient spaceborne colonies of appreciable mass - we'er talking something along the lines of Island Three here.

One of the proposed Orion ship designs weighed 8 million tons - essentially an entire city and all its support facilities.

I don't think 8 million tons is enough for an ark. It might be good enough for a sleeper ship or seed ship, or for a ship with a biologically immortal/cyborg/robotic/digital crew.

Interstellar arks are all well and good, but we still need to have a complex infrastructure in place in the Solar system in order to construct just one such vessel, which would be a massive project. Not only that, but we would need considerable practical experience in constructing and maintaining self-sufficient spaceborne colonies of appreciable mass - we'er talking something along the lines of Island Three here.



I don't think 8 million tons is enough for an ark. It might be good enough for a sleeper ship or seed ship, or for a ship with a biologically immortal/cyborg/robotic/digital crew.

Yeah, I agree that the first step would be a self-sufficient space colony in Earth orbit before we send 100,000 people across space on a journey that may take centuries. Best to trouble-shoot these things first. The ark could function as a space colony, though. The engines could be added later.

The 8 million ton Orion design was designed to carry 100,000 people, but I don't know very much about the other specs (like how much space each person would get). 100,000 was also considered the maximum population. I think it's capacity is stated as '50,000-100,000'.

Yeah, I agree that the first step would be a self-sufficient space colony in Earth orbit before we send 100,000 people across space on a journey that may take centuries. Best to trouble-shoot these things first.

Indeed, but you don't get (much) experience by doing something just once.

The ark could function as a space colony, though. The engines could be added later.

It might even happen as part of a colony's decision to break away, literally as well as politically/culturally.

The 8 million ton Orion design was designed to carry 100,000 people, but I don't know very much about the other specs (like how much space each person would get).

I think space is very important, or at least the perception of space. One way we can gain experience of space management is through the construction of arcologies; the advantage being that we don't even have to leave the Earth's surface to do so.

100,000 was also considered the maximum population. I think it's capacity is stated as '50,000-100,000'.

I know next to nothing about population genetics, and I realise that one's gut can be seriously misleading, but 100,000 "feels right". Of course, independant confirmation either way would be entirely welcome.

Indeed, but you don't get (much) experience by doing something just once.

True, it is likely that we'd build a series of smaller colonies before starting construction on the ark.

It might even happen as part of a colony's decision to break away, literally as well as politically/culturally.

Yep - could be (and has been) the premise for some good stories.

I think space is very important, or at least the perception of space. One way we can gain experience of space management is through the construction of arcologies; the advantage being that we don't even have to leave the Earth's surface to do so.

Arcologies are pretty much synonymous with urbanates - essentially an entire city in one large (1 km wide) building. I think building these would be a good idea anyway.

I know next to nothing about population genetics, and I realise that one's gut can be seriously misleading, but 100,000 "feels right". Of course, independant confirmation either way would be entirely welcome.

Well, I remember reading somewhere that the human population of the entire world was reduced to around 10,000 during one of the recent ice ages. So if 10,000 is sufficient to repopulate the planet, 100,000 should be more than enough for a colony ship.

Its interesting, how would the colonists keep in contact with the Earthbound people. How would relations be. I think everyone would be on the edge of their seats upon the shuttles landing on an Earthlike planet.

Its interesting, how would the colonists keep in contact with the Earthbound people. How would relations be. I think everyone would be on the edge of their seats upon the shuttles landing on an Earthlike planet.

They wouldn't keep in contact with Earth. If you're 30 light years from earth, that's a 30 year delay in communications. If you're 18,000 light years from earth, that's an 18,000 year delay. The galaxy is 100,000 light years in diameter, roughly. It might be possible to maintain some kind of loose confederation of nearby star systems based around a shared culture, but a 'galactic empire' is pretty much a ridiculous idea because of the distances involved.

The colonists on the ark would form an autonomous city-state in space. They would be autonomous both in terms of resources, and politically.

It may not be real-time, but the outgoing ship would still be able to receive news from home, especially if laser sails are used.

I don't think it makes sense to send ships that will probably be outrun by more advanced ships invented later. We would want to wait until interstellar technology is mature enough to leave our solar system. In the meantime, we should focus on colonizing Mars and possibly some of Jupiter's and Saturn's satellites.

Well, that's assuming that faster than light travel is even possible, which it may never be (our current understanding of physics rules it out). While I'm not opposed to colonizing Mars and other parts of the solar system, I think it would be worth it to send an ark to a relatively close (100 light years or less) system if we detected a habitable world there. Even better, we could look for a system that has multiple potentially habitable worlds - I think this is a plausible scenario for space colonization.

Some hard numbers on the issue of having an adequate gene pool:

What is the minimum number of colonists? For genetic reasons, if the number of colonists is too small and no new colonists arrive via starship, the colony will eventually die out due to inbreeding. This is important on a slower-than-light starship colony mission were every microgram is expensive, you do not want to waste payload mass on unnecessary colonists, and follow-up missions are unlikely. However this is a non-issue with FTL starships bringing new immigrants every week, the new colonists will quickly swell the colony size large enough to avoid genetic problems.

The minimum number of colonists also applies to a Generation starship, which is after all sort of a traveling colony.

If you do not want to fiddle with math below, the bottom line is as follows. If the colony is to survive inbreeding for up to 100 years, you'll need a minimum of 500 randomly chosen colonists or 50 hand-picked colonists all who are unrelated and of breeding age. If the colony is to have enough genetic diversity to survive for thousands of years, you'll need a minimum of 5000 randomly chosen colonists or 500 hand-picked colonists all who are unrelated and of breeding age. That's if I have not made a silly mistake in arithmetic.

There's more, but I'm surprised the numbers are apparently so low.