[Bryan See]

From the Wall Street Journal's blog, titled "Gary Johnson Calls for Human Settlement of Other Planets", explains the need for humanity to settle on other planets:

Candidates often discuss their plans for their first day in office, but rarely the future of the human race billions of years after their presidency.

“We do have to inhabit other planets,” Gary Johnson, the Libertarian Party presidential candidate said in an interview on ABC’s “This Week” on Sunday. “The future of the human race is space exploration.”

Mr. Johnson was questioned on the topic because he had once said he opposed certain programs to mitigate climate change because “the long-term view is that in billions of years, the sun is going to actually grow and encompass the earth.”

Mr. Johnson said the 2011 remarks were humorous and that he supports both space exploration and a role for environmental regulation.

“We should be prudent with the environment,” Mr. Johnson said, “The EPA exists to protect us against individuals, groups, corporations that would do us harm. Pollution is harm.”

In fact, private space companies, such as SpaceX, has undertaken such. The Interplanetary Transport System, formerly known as the Mars Colonial Transporter, is due to be revealed this month.

EDIT: We can perhaps escape from Earth in any event of something happens to prevent any manned space program from being realized, I mean, there's a looming probability of a Donald Trump presidency. There could be World War III, where any conventional conflict goes nuclear very rapidly, and/or there's social movements that's anti-technology, anti-science, and anti-modern, such as Putinism and Dugin's Eurasianism, which calls for humanity to be "rooted in the soil" without "individual rights" and "technological progress".

EDIT #2: There are habitable exoplanets, the nearest discovered is Proxima b. I bet that humanity will get there in the future.

[Scourge of Ages]

This is actually relevant to my interests, at the moment...

So I'm maybe sort of writing a thing, and the thing includes three pair of colony ships traveling to nearby, extra-solar, earth-like (for the purposes of the thing) planets. Any astronomer(s) around here have three good candidates that could theoretically harbor human life?

[NGTM-1R]

Well, depends on what you mean by "harbor human life".

Do you want to be able to walk around without a spacesuit, or are you more thinking you want to play Real-Life Outpost? The latter is easy.

[Scourge of Ages]

Do you want to be able to walk around without a spacesuit, or are you more thinking you want to play Real-Life Outpost? The latter is easy.

Without a spacesuit, after some sci-fi terraforming. Let's say "could conceivably have liquid water, and some sort of non-deadly atmosphere".

EDIT: I know we can't exactly see that from here, so basically I'm looking for known exoplanets in the habitable zone, about 5-30 ly away.

[Bryan See]

Without spacesuit before terraforming is lethal. One can't breathe, one can't hear anything, one risk getting killed by cosmic radiation and one getting crushed by intense pressure.

[LaineyBugsDaddy]

Bryan, you're an idiot. They're talking about a planet that at least has breathable atmosphere before any additional terraforming.

[Scourge of Ages]

Upon investigation of the Wikipedia page "List of Potentially Habitable Exoplanets", I've noticed that most of the known exoplanets in the habitable zone are really really massive. That means that they're not exactly "habitable" by humans unless they're good with a gravity of 3-8x that of Earth.
It makes sense, though, that the biggest planets are the ones we find first, due to the way they're discovered.

Eh, I'll probably just make something plausible-sounding up.

[NGTM-1R]

We can almost certainly handle high-gravity adapting up to 4-5G, but 6G is probably out of the question.

[jr2]

Bryan, you're an idiot that's idiotic <OR> nonsense. They're talking about a planet that at least has breathable atmosphere before any additional terraforming.

FTFY.  Although I do imagine it was meant in a non-personal way, being on the internet, it's best to be more specific with these sorts of things...

[FlamingCobra]

What you'd probably want to do is colonize an asteroid belt near an exoplanet that you want to terraform. You'd then use materials from the asteroid belt to build Stanford tori, Bernal spheres, and eventually O'Neill colonies. Then you'd be able to get started on terraforming and you wouldn't have to worry about gravity wells and ****ing around with making space suits for everyone.

[perihelion]

Stupid question - Once you have all of those nice orbital habitats with all of the infrastructure and commerce necessary to provide materials and equipment and personnel required for something as ginormous as a terraforming effort... why would you WANT to saddle yourself to a gravity well?

Put in different words - IF you have the technology capable to colonize an asteroid belt several light-years from Earth, why ever set foot on a high-G planet again?  What can you do at the bottom of a well that you cannot already (by implication) do in orbit?

Exoplanets would be interesting, I'm sure, from a scientific and spirit-of-adventure perspective.  Exobiology and final frontiers etc.  But if you already have the capability to terraform entire planets, by definition, you've got more than enough tech at your disposal to make living in orbital habitats and/or asteroids perfectly comfortable.  And a heck of a lot more fun!

[MP-Ryan]

This entire conversation has me wishing the next Expanse book would hurry up.

[Scotty]

Stupid question - Once you have all of those nice orbital habitats with all of the infrastructure and commerce necessary to provide materials and equipment and personnel required for something as ginormous as a terraforming effort... why would you WANT to saddle yourself to a gravity well?

Put in different words - IF you have the technology capable to colonize an asteroid belt several light-years from Earth, why ever set foot on a high-G planet again?  What can you do at the bottom of a well that you cannot already (by implication) do in orbit?

Exoplanets would be interesting, I'm sure, from a scientific and spirit-of-adventure perspective.  Exobiology and final frontiers etc.  But if you already have the capability to terraform entire planets, by definition, you've got more than enough tech at your disposal to make living in orbital habitats and/or asteroids perfectly comfortable.  And a heck of a lot more fun!

Presumably, expand in low-cost fashion.  It's significantly (several orders of magnitude) easier to sow ten thousand acres of crops terrestrially than it is to build habitats to house ten thousand acres of crops in a belt asteroid environment.

Habitats: medium start up, medium sustainment, high expansion difficulty
Terrestrial (terraformed): very high start up, very easy sustainment, very low expansion difficulty.

[NGTM-1R]

Also, vulnerability. Spaceborne habitats are extremely vulnerable to natural and manmade disaster, and many of the threats against them are orders of magnitude more dangerous due to the high velocities involved with any space-related activity. Ground-based habitats have more defenses, include the local atmosphere, and the ground itself; twenty meters of rock or dirt as radiation and impact shielding will accomplish things most space-based habitats can only dream of.

[Bryan See]

Maybe we can generate an artifically induced magnetic field.

[666maslo666]

Colonization of space is something that could be easily tried here on Earth, minus the rockets. Advanced closed loop life support, ISRU, need to survive while being cut off from civilization, these are all very important techs that can be simulated and perfected right now. I would be much more optimistic about humanity settling space if we already had a self-sustaining permanently manned base somewhere in Antarctica or some desert to prove it can be done. Something like Biosphere project, but with space habitats in mind.

https://en.wikipedia.org/wiki/Biosphere_2

[Bryan See]

That's cool. Perhaps we can do as an open-source, crowdsourced project in the near future.

[MikeRoz]

EDIT: We can perhaps escape from Earth in any event of something happens to prevent any manned space program from being realized, I mean, there's a looming probability of a Donald Trump presidency. There could be World War III, where any conventional conflict goes nuclear very rapidly, and/or there's social movements that's anti-technology, anti-science, and anti-modern, such as Putinism and Dugin's Eurasianism, which calls for humanity to be "rooted in the soil" without "individual rights" and "technological progress".

Why exactly would a Trump presidency be the end of a manned (US) space program, again?

Trump promises space, tech jobs for Central Florida

“I will free NASA from the restriction of serving primarily as a logistical agency for low Earth-orbit activities,” he told thousands of supporters. “We will instead refocus on space exploration. Under a Trump administration, Florida and America will lead the way into the stars.”

[StarSlayer]

[Flaser]

Here is Charles Stross' rant from 2007, the High Frontier Redux. Everything he wrote back then still happens to be true today.

TLDR: He's another skeptic who points out we'd probably colonize the antarctic or deep sea first as they're waaaay easier ventures with higher return on the capital.