Inhabitable Planets Too Close Together?

One issue people forget about those cryogenic ships is that the ship itself wasn't preserved. Material ages, even with the best designs. And that is an issue that won't likely change. Even in the Honorverse, they are clearly ships removed from service due to age. An age measured in decades, but still there. And ALL the ships need regular maintenance.
And don't get me started on the likelihood of a computer running that long, hundreds of years, without locking up. I can see Microsoft bidding on that contract. "Hell, but hell no!"


The likelihood of a sleeper ship or generational ship is nill. It would more likely reach its destination as nothing but an odd asteroid with a dead cargo.

If there is ever a possibility of colonization, it will require FTL of one sort or another. Or very fast ships that make use of time dilatation to also preserve the ship. Even then there would be serious limits.

Hell, in a personal novel I had written, the first FTL was measured at about 60+ cee. Sounds fast by our standards. That is less than 1 light-year in five days. By interstellar distances, that will quickly have the usefulness of a rowboat in the Atlantic. Alpha Centari is already nearly a month away. Let's now go 100 LY? Two years one way.

The "age" of a ship's system is more an issue of operating time, not chronology.

The most obvious critical system is propulsion.

I would expect an STL colony ship to boost for a few months at 1/10 gee or a few years at 1/100 gee, then coast for decades or centuries with zero degradation of the system.

In flight power of a few megawatts could be provided by a thermoisotope power source with no moving parts. Just pick an isotope with a half-life comparable to travel time and there will be minimal degradation.

Your lack of faith in computer liability is inspired by experience with modern systems that are constantly stressed by downloading data that can corrupt programs. Given computers that have their operating systems in ROM rather than RAM, they will be reliable for centuries.

I would expect the colonists to remain in cold sleep while a small crew rotates live duty just to back up the computer.

swalke813 wrote:One issue people forget about those cryogenic ships is that the ship itself wasn't preserved. Material ages, even with the best designs. And that is an issue that won't likely change. Even in the Honorverse, they are clearly ships removed from service due to age. An age measured in decades, but still there. And ALL the ships need regular maintenance.
And don't get me started on the likelihood of a computer running that long, hundreds of years, without locking up. I can see Microsoft bidding on that contract. "Hell, but hell no!"


The likelihood of a sleeper ship or generational ship is nill. It would more likely reach its destination as nothing but an odd asteroid with a dead cargo.

If there is ever a possibility of colonization, it will require FTL of one sort or another. Or very fast ships that make use of time dilatation to also preserve the ship. Even then there would be serious limits.

Hell, in a personal novel I had written, the first FTL was measured at about 60+ cee. Sounds fast by our standards. That is less than 1 light-year in five days. By interstellar distances, that will quickly have the usefulness of a rowboat in the Atlantic. Alpha Centari is already nearly a month away. Let's now go 100 LY? Two years one way.

swalke813 wrote:The likelihood of a sleeper ship or generational ship is nill. It would more likely reach its destination as nothing but an odd asteroid with a dead cargo.

If there is ever a possibility of colonization, it will require FTL of one sort or another. Or very fast ships that make use of time dilatation to also preserve the ship. Even then there would be serious limits.

In the real world, maybe you have a point, maybe.

But in the Honorverse we have two specific listed instances of STL colonization (Manticore and Grayson), one that specifically included cryo-sleep (Grayson), and a general history that includes a period of dangerous FTL exploration to discover planets for STL ships to colonize.

The potential for problems with a Cold Sleep ship get really interesting.

Do you put the power plant in some kind of minimal mode and just keep the monitors for the Cryo system/indivdual pods active along with some sort of scheme to wake up the crew when you get to the destination?

If you shut down the power plant and/or the drive, for that LONG streach between getting to your crusing speed and needing to slow down to enter the proposed orbit for your destination, what options do you have for making sure you can restart it again?
We are talking centuries in some cases of effecticly ballistic travel.

Do you have people awake all the time- probably in rotation- to monitor the systems and be available to TRY and fix any problems with either ships/cryo/other systems including navigation and damage contro?

How do you protect against some group- either the caretakers at any give time or first to awaken- from effectivly taking over the colony with their own power base when you get there?

How much fuel for the powerplant (even fusion) can you carry?

How do you protect all that software from things like radiation (including cosmic rays), accidental damage and even somebody just screwing up and corrupting instructions? That doesn't begin to cover flaws in the basic programing or something deliberate.

Try books like Footfall by Niven for one group taking control of a sleeper ship.

For problems on bringing everything back to life there was a TV series, Earth II, where the ship was essentially a projectile until some piece of equipment started turning on things to wake up the crew and THEN there began to be failures in all sorts of systems. Not the least of their problems was that the mission had been sabotaged from the start and there was already a base and population on the planet. Really doesn't help when you get to the destination and the ship looks to kill itself. Some of the cargo planetfall containers made it to the ground intact but the colony was more than decimated (as best I remember) so that only the major people involved survided getting down to the surface.

namelessfly wrote:The "age" of a ship's system is more an issue of operating time, not chronology.

The most obvious critical system is propulsion.

I would expect an STL colony ship to boost for a few months at 1/10 gee or a few years at 1/100 gee, then coast for decades or centuries with zero degradation of the system.

In flight power of a few megawatts could be provided by a thermoisotope power source with no moving parts. Just pick an isotope with a half-life comparable to travel time and there will be minimal degradation.

Your lack of faith in computer liability is inspired by experience with modern systems that are constantly stressed by downloading data that can corrupt programs. Given computers that have their operating systems in ROM rather than RAM, they will be reliable for centuries.

I would expect the colonists to remain in cold sleep while a small crew rotates live duty just to back up the computer.

Age can easily be an issue. The shuttles was said to have more of an issue of age, rather than miles. A ship isn't only a hull. It is very complicated electronics and mechanical systems.
Age affects things like rubber, plastics, technology etc. Especially in an atmospheric environment. And some of that won't likely handle vacuum very well. Or cold. So you can't just decompress the ship. In fact, you probably have to maintain a reasonable temperature.
Don't forget that the colonists supplies also have to sit in storage for the entire trip, then be viable when they arrive.

Remember that we have rarely operated technologies on a scale measured in decades, and never in centuries. The closest we've come is satellites, and those are very limited in comparison to a crewed ship. And even they've had a lot of failures.


The only way around that problem is keeping the trip short enough that equipment survivability is reliable. That means at least modest FTL capability, combined with sleep technology for the crew, or speed close to light and use time dilatation to mimic placing the whole ship in stasis.
A trip measured in years might be doable. A trip measured in decades will have rapidly increasing risks. And a trip measured in centuries is likely impossible. Too much time for too many things to go wrong.

I am presuming that we aren't going to launch these long term missions fora century or two. We don't have a viable fusion reactor yet much less a fusion rocket with the power to mass ratio needed to get decent accelleration. Think of a stationary steam engine compared to a modern jet engine.

Boeing routinely does tests oflongterm reliability using accelerated stress cycles.

I expect that the ship's computer will be embedded in a shielded core and the computer itself and memory system might be relatively primitive so that the bulky components will be less vulnerable to radiation damage. They might even be Babbage's steam powered mechanical difference engines complete with chains of punch cards, LOL. Seriously, IC systems with 1970s era component densities might be used to minimize vulnerability would be wise.

Everything is probably intentionally designed to survive exposure to vacuum and cold. Vacumm = no air = no oxidation. Near absolute zero cold = extremely slow chemical reactions = minimal decay.

Finally; it is quite possible that failures of the early sleeper or generation ships were common. They might have been launched anyway because the colonists were undesirables and they accepted the risk because the alternative was death. The existing colonies were founded by
people who were lucky enough to survive. A good analogy would be the Polynesians sending small groups of settlers out on voyaging canoes.

swalke813 wrote:

namelessfly wrote:The "age" of a ship's system is more an issue of operating time, not chronology.

The most obvious critical system is propulsion.

I would expect an STL colony ship to boost for a few months at 1/10 gee or a few years at 1/100 gee, then coast for decades or centuries with zero degradation of the system.

In flight power of a few megawatts could be provided by a thermoisotope power source with no moving parts. Just pick an isotope with a half-life comparable to travel time and there will be minimal degradation.

Your lack of faith in computer liability is inspired by experience with modern systems that are constantly stressed by downloading data that can corrupt programs. Given computers that have their operating systems in ROM rather than RAM, they will be reliable for centuries.

I would expect the colonists to remain in cold sleep while a small crew rotates live duty just to back up the computer.

Age can easily be an issue. The shuttles was said to have more of an issue of age, rather than miles. A ship isn't only a hull. It is very complicated electronics and mechanical systems.
Age affects things like rubber, plastics, technology etc. Especially in an atmospheric environment. And some of that won't likely handle vacuum very well. Or cold. So you can't just decompress the ship. In fact, you probably have to maintain a reasonable temperature.
Don't forget that the colonists supplies also have to sit in storage for the entire trip, then be viable when they arrive.

Remember that we have rarely operated technologies on a scale measured in decades, and never in centuries. The closest we've come is satellites, and those are very limited in comparison to a crewed ship. And even they've had a lot of failures.


The only way around that problem is keeping the trip short enough that equipment survivability is reliable. That means at least modest FTL capability, combined with sleep technology for the crew, or speed close to light and use time dilatation to mimic placing the whole ship in stasis.
A trip measured in years might be doable. A trip measured in decades will have rapidly increasing risks. And a trip measured in centuries is likely impossible. Too much time for too many things to go wrong.

I expect that 90% fuel would be reasonable. DeltaV = Exhaust Velocity x Ln( mass ratio). The ship could accelerate to 1/10 Cee then decelerate or accelerate to 2/10 cee then decelerate using ram fields. If the ram fields can be used to gather reaction mass to augment thrust, then transit velocity of .5 Cee is doable. Read Footfall by Niven and Pournelle.

Brigade XO wrote:The potential for problems with a Cold Sleep ship get really interesting.

Do you put the power plant in some kind of minimal mode and just keep the monitors for the Cryo system/indivdual pods active along with some sort of scheme to wake up the crew when you get to the destination?

If you shut down the power plant and/or the drive, for that LONG streach between getting to your crusing speed and needing to slow down to enter the proposed orbit for your destination, what options do you have for making sure you can restart it again?
We are talking centuries in some cases of effecticly ballistic travel.

Do you have people awake all the time- probably in rotation- to monitor the systems and be available to TRY and fix any problems with either ships/cryo/other systems including navigation and damage contro?

How do you protect against some group- either the caretakers at any give time or first to awaken- from effectivly taking over the colony with their own power base when you get there?

How much fuel for the powerplant (even fusion) can you carry?

How do you protect all that software from things like radiation (including cosmic rays), accidental damage and even somebody just screwing up and corrupting instructions? That doesn't begin to cover flaws in the basic programing or something deliberate.

Try books like Footfall by Niven for one group taking control of a sleeper ship.

For problems on bringing everything back to life there was a TV series, Earth II, where the ship was essentially a projectile until some piece of equipment started turning on things to wake up the crew and THEN there began to be failures in all sorts of systems. Not the least of their problems was that the mission had been sabotaged from the start and there was already a base and population on the planet. Really doesn't help when you get to the destination and the ship looks to kill itself. Some of the cargo planetfall containers made it to the ground intact but the colony was more than decimated (as best I remember) so that only the major people involved survided getting down to the surface.

Uh guys in the Honorvers they don't use cold sleep they used cryogenic hibernation which slowed the bodies by a factor of 100 so a 500 year trip would only age the colonist by 5 years. (Reed the UHH in More than Honor) IIRC the colonist had to be awakened several times over the journey to exercise and more than likely conduct maintainece according to the UHH it was done for one month every 60 years/6 months.

saber964 wrote:Uh guys in the Honorvers they don't use cold sleep they used cryogenic hibernation which slowed the bodies by a factor of 100 so a 500 year trip would only age the colonist by 5 years. (Reed the UHH in More than Honor) IIRC the colonist had to be awakened several times over the journey to exercise and more than likely conduct maintainece according to the UHH it was done for one month every 60 years/6 months.

Cryogenic Hibernation is Cold Sleep in this context. You’re thinking of either Suspended Animation or Cryogenic Freezing. With Suspended Animation (as in “Red Dwarf”) the person is put in an energy field where they are removed from time & don’t pass through the demission of Time while traveling in space. With Cryogenic Freezing the body is completely frozen then thawed out at the destination (“corpsicle”) as in “A World Out of Time” and like some bugs found in the arctic.

Toss out two thirds because of other conditions, such as double stars which would disupt planetary systems

And it has already been proven that double/triple, even quadruple star systems CAN have planets in a steady orbits, it´s just (much) less likely.

In that radius, there are almost 17,000,000 stars. Of those, around 3,000,000 stars are of stellar classifications compatible with habitable zones.

And there has been quite some theorising and modelling suggesting that there are conditions that can extend those habitable zones a fair amount.
Including to red dwarf stars, which there´s plenty of.

No, it is not absurd to have as many habitable systems as Weber has put into the Honorverse

Nope, it MAY be too high, but it may also be too LOW... So easily within the realms of possibility at least.

There´s also the possibility of terraforming, IIRC it has been mentioned in the books, but no real definitions on how much it can really do.