How to leave the Solar system.

[Astromancer]

Basically, this thread is about groups working on interstellar colonisation in the Transhuman Space setting. Although such groups would logically sent out AIs in robotic forms first, this thread isn't about seeding the Universe with AIs or how humans will never leave the Solar system. It's about who is working on taking flesh and blood human and parahuman colonists to other star systems.

That said, what kinds of groups are making seriously committed efforts toward interstellar colonisation? And also, what kind of activities surrounding these efforts make good plot hooks

[RogerBW]

I'm assuming you're also writing out the easiest remaining option, which is to encode the humans, then build them bodies at the far end with local materials and download the recordings into them. You want actual human bodies transported across interstellar distances.

Looking at Spaceships 8, the best delta V drive available in TS is the antimatter plasma rocket, 120mile/second per tank. Let's assume we have a ship that's 95% fuel (one Smaller System with drive, control room, payload and so on; it doesn't have to be manoeuvreable, it just has to work); 120mile/s × 19 × 3 = 6840 mile/s. Cruise speed is half that, and at 1/300 gravity it'll take over five years to get to that speed, during which time it'll cross about 1/20 of a light year. Take twice that distance off the 4.244 light years to Proxima Centauri and that leaves over 225 years of cruise time at 3240 mile/s, 236 with the acceleration/deceleration time.

(I'm ignoring armour against interstellar dust.)

So that's the fastest that TS tech can manage it with an on-board drive. (I have a nasty feeling that a network of launching lasers would rapidly turn into a short war.) Given this mission duration, how can we run the ship?

- generation ship. Obvious ethical problems.

- long lifespans. For humans, TS tech is probably up to it, for AIs definitely, and at least everyone on board is a volunteer.

- keep at least some of the intelligences in nanostasis / backup storage for some or all of the mission. AIs can underclock themselves most of the time and spin up again if something major happens, and/or wake up the organics.

[Fred Brackin]

Originally Posted by RogerBW

I Take twice that distance off the 4.244 light years to Proxima Centauri and that leaves over 225 years of cruise time at 3240 mile/s, 236 with the acceleration/deceleration time.
.

Unfortunately that leaves you at the red dwarf of the trinary system. Alpha Centauri A and B are actually of the right age and metallicity to produce Sun-like solar systems and having the possibility of 2 of those within 10 AU is so much better than just one red dwarf.

So we bite the bullet and go just a little farther. a fresh quote from google makes that 4.367 ly and adds only 6.5 years to the journey time.

I'm sure you're right for a simple single stage vehicle. Using multiple stages and a magsail for deceleration could probably do better but not an order of magnitude better. Maybe a factor of 2-ish for 1 century.

[Shostak]

A religious group could make a good candidate for people keenly interested in leaving the Sol system for another. It is easy to imagine one being interested in creating a whole new society with no competing memes and perhaps with no trans/para/meta humans, uplifts, etc., to muck up the purity of the population.

[Astromancer]

Originally Posted by RogerBW

I'm assuming you're also writing out the easiest remaining option, which is to encode the humans, then build them bodies at the far end with local materials and download the recordings into them. You want actual human bodies transported across interstellar distances.

No, but as in the film Interstellar I don't see that as the "fun way."

Looking at Spaceships 8, the best delta V drive available in TS is the antimatter plasma rocket, 120mile/second per tank. Let's assume we have a ship that's 95% fuel (one Smaller System with drive, control room, payload and so on; it doesn't have to be manoeuvreable, it just has to work); 120mile/s × 19 × 3 = 6840 mile/s. Cruise speed is half that, and at 1/300 gravity it'll take over five years to get to that speed, during which time it'll cross about 1/20 of a light year. Take twice that distance off the 4.244 light years to Proxima Centauri and that leaves over 225 years of cruise time at 3240 mile/s, 236 with the acceleration/deceleration time.

(I'm ignoring armour against interstellar dust.)

So that's the fastest that TS tech can manage it with an on-board drive. (I have a nasty feeling that a network of launching lasers would rapidly turn into a short war.) Given this mission duration, how can we run the ship?

Researching advanced drives would be a vital goal.

- generation ship. Obvious ethical problems.

You mean that the children are committed to the voyage too with no choice? That happens a great deal. The settlers in 17th century America, especially the poorer ones committed their children without their consent. in the THS setting people regularly genetically modify their unborn children. We even read about people removing the sex drive from their children, having them born androgynes, or simply having the French Biochemical Lady prevent them from growing up. The ethical issues involved in a Generation Starship are trivial compared to those.

- long lifespans. For humans, TS tech is probably up to it, for AIs definitely, and at least everyone on board is a volunteer.

Other than bioroids, everybody except the young children and the children yet to be born, would be volunteers.

- keep at least some of the intelligences in nanostasis / backup storage for some or all of the mission. AIs can underclock themselves most of the time and spin up again if something major happens, and/or wake up the organics.

Nonostasis seems like the strongest means of getting beyond the solar system. If nanostasis can preserve mind and body over centuries, then a large population could be brought out of the solar system with relatively little mass invested in life support. AIs could build the life support when they reached the new system.

[Astromancer]

Originally Posted by Fred Brackin

Unfortunately that leaves you at the red dwarf of the trinary system. Alpha Centauri A and B are actually of the right age and metallicity to produce Sun-like solar systems and having the possibility of 2 of those within 10 AU is so much better than just one red dwarf.

So we bite the bullet and go just a little farther. a fresh quote from google makes that 4.367 ly and adds only 6.5 years to the journey time.

I'm sure you're right for a simple single stage vehicle. Using multiple stages and a magsail for deceleration could probably do better but not an order of magnitude better. Maybe a factor of 2-ish for 1 century.

Yes, we need to pick an optimal star to begin with. Luckily, with the THS there would be astronomic observatories out beyond the orbit of Neptune looking for planets for decades before any ship would leave. They'd have a vastly better idea of where to go than we would have.

[Astromancer]

Originally Posted by Shostak

A religious group could make a good candidate for people keenly interested in leaving the Sol system for another. It is easy to imagine one being interested in creating a whole new society with no competing memes and perhaps with no trans/para/meta humans, uplifts, etc., to muck up the purity of the population.

As in Massachusetts, Pennsylvania, or Utah, a religious group would have the passion and focus to make good colonists. People might worry about the resulting societies.

[Fred Brackin]

Originally Posted by Astromancer

Yes, we need to pick an optimal star to begin with. Luckily, with the THS there would be astronomic observatories out beyond the orbit of Neptune looking for planets for decades before any ship would leave. They'd have a vastly better idea of where to go than we would have.

<shrug> If those observatories (which don't need to be beyond Neptue) can prove that Alpha C a +b are without interest then you might be putting the kibosh on the whole concept.

After Alpha C the nest realistic candidate might be Tau Ceti but that's 12 ly away. Almost tripling the length of the trip. After that it might be 40 ly or more.

[Astromancer]

Originally Posted by Fred Brackin

<shrug> If those observatories (which don't need to be beyond Neptue) can prove that Alpha C a +b are without interest then you might be putting the kibosh on the whole concept.

After Alpha C the nest realistic candidate might be Tau Ceti but that's 12 ly away. Almost tripling the length of the trip. After that it might be 40 ly or more.

Well, who said the goal was an earthtype planet or a terrafirmable one? Suitable resources for life would mean something different in Transhuman Space. And surely the colonists could go from star to star until they got what they wanted/needed.

[Fred Brackin]

Originally Posted by Astromancer

Well, who said the goal was an earthtype planet or a terrafirmable one? Suitable resources for life would mean something different in Transhuman Space. And surely the colonists could go from star to star until they got what they wanted/needed.

Did I mention an Earth-like planet? I speciifically mentioned the possibility of 2 "usable solar systems" at Alpha Centauri. We can already tell that Tau Ceti has what is probably a usable solar system by TS standards.

What I'm trying to convey to you is that you shouldn't be too picky about your target star because there are a lot more bad choices than good ones out there.

As for going from star to star that would need you to go from places where you could build a new STL starship to other places where you could build another one. It is very likely that there stars out there whose systems are no more useful to STL travellers than Earth's Oort Cloud and if you're happy in Earth's Oort why are you going anywhere?