Interstellar Colonization: Restarting from Scratch

[Eagle1Division]

Okay, one thing I've never seen addressed is the process of creating a new infrastructure on an exo-solar planet. There's a huge amount of discussion on interstellar drive systems, tech, FTL, etc. etc, but I've never actually seen any ideas or proposals on how to create a whole new civilization from scratch, which would be necessary for interstellar colonization.

The challenges are as follows:
Build an infrastructure capable of building and running a small city, using incredibly tight mass restrictions.

Talking with a friend one of the things I've concluded is the planet would need to have Calcium, Iron, and Carbon all heavily present in the crust.

Iron, of course, to create metals.

Calcium and Carbon to make concrete and cement.

But what about the machinery? How do you, with incredibly tight mass restrictions, build refineries, factories, quarries, mines, drills, etc? Where do you even begin? What do you take with you and what do you build on-site?

I think the necessary things to bring would at least be machine-shops (automated machine shops, more akin to a 3-d printer) and equipment to quarry and refine metal to make things with the machine shop.

 

[Artlav]

Hm.
We already colonized one planet, the one you sit on.
What's the problem of repeating the feat?

We're not in any hurry to set up the colony, so most of the slowboat would be filled by people (or genetic material bank), the records of all knowledge we can gather, and some basic machinery.

From there it would take a few decades to built up all the infrastructure to manufacture anything that can be made on earth, assuming material existence on the planet.

---------- Post added at 20:48 ---------- Previous post was at 20:44 ----------

Actually, no. That assumes a habitable planet.
If it has to be terraformed before settling in, then there would be a time limit.

In that case you would need at least a pair of fabbers along with digging/mining/prospecting equipment.
This way you would be able to make repairs and produce single items of any sort, allowing an extensive survival.

Then go to part A of the post.

 

[jedidia]

Iron, of course, to create metals.

Steel alloys is what you're thinking of. Just nitpicking. Professional deformation from my days as a toolmaker...

 

[T.Neo]

I think highly advanced fabrication technology- the sort of "automated machine shop" you describe, is pretty much an essential requirement.

For starters, humans and their associated biosphere need as the very basics, CHON: carbon, hydrogen, oxygen, and nitrogen (sometimes rendered as CHONPS, with 'PS' being phosphorous and sulfur, elements also important to biology but found in lower quantities). In addition we need smaller amounts of other elements (here's a list).

Our technology is primarily based on iron, aluminium, and hydrocarbons.

You could say that steel is the cornerstone of human civilisation; we produce over a billion tons of iron per year, and steels are found in everything from ships to buildings to firearms to cutlery to spacecraft. If something around you doesn't have steel in it, steel was most probably used to make it- even your food. For steel we'll need iron and carbon primarily, but remember that alloys with increased strength or special properties such as corrosion resistance need other elements as additives, and these can be hard to find.

Aluminium is best for lightweight applications- aircraft, some land vehicles, portable equipment, temporary structures, etc. Aluminium is quite energy intensive to refine from bauxite ore; before modern methods of refinement it was regarded as a precious metal; it's the third most abundant element in our crust, but at the time refining large amounts of it was very tricky. Aluminium alloys can be made quite strong, but these, like steel, require additional elements that are generally less common. Another advantage of aluminium is that it is a good conductor, and can be used as a substitute for much rarer copper in many situations.

Plastics, generally made of hydrogen and carbon, are ubiquitous in modern society. Plastics are lightweight, can be fairly strong, and are corrosion resistant, however they generally do not handle heat, certain chemical environments, scuffing/abrasion and severe forces well. In addition, some plastics can be damaged by UV light. However, plastics are still heavily useful. Their density and strength makes them perfect for many applications that metals would both be too much trouble and/or too heavy/overkill for.

Plastics can be made into a variety of shapes as well; they can be moulded with ease, and machined to varying degrees of success, although the former requires moulds and these are expensive, intensive, and time-consuming to make, can only be used for one part, and only make sense if there is heavy mass production. However, 3D printing, for example, with plastics could be very advantageous, and indeed the 3D printing machines that we see today use thermoplastics as construction materials.

In addition, polymers or materials that can be made of polymers can potentially be manufactured using biology. In addition, plastics mostly require the common elements hydrogen and carbon, though it should be noted that some polymers (PVC, Teflon) require rarer elements such as halogens.

Another set of important materials are ceramics and stone. Stone has historically been used both in tools and as a building material, and ceramics are still used widely in construction, for example (brick, etc), as well as in items such as crockery, and specialised applications or tools. High-temperature ceramics are useful for many things, and could assist the development of several other technologies (such as certain fuel cells, for example). Silicon and oxygen are common, though advanced ceramics might need firing and advanced preparation that could be energy and resource intensive.

A useful resource is the Wikipedia article on the abundance of elements in Earth's crust, and this graph showing the abundance of the most common elements in lunar regolith is also interesting.

You'd probably want to go somewhere with relatively abundant volatiles (like Mars) rather than somewhere that is relatively volatile-poor (like the Moon). In addition, you want to make as many things as possible, or as much of things as possible, out of elements that are common in your environment. Rarer elements will either be concentrated into veins of ore, or will be spread around the environment at low concentrations (the former if your planet has or has had an active hydrosphere, the latter in both cases).

My garden is a good example for a random place where you'd find certain stuff. There's plenty of carbon (in the plant life and in the biological component of the soil), as well as hydrogen (again in the latter), oxygen is pretty abundant, and the soil is made up of some mineral I can't even name (there's quartz and some red stuff, so there's silicon, probably a bit of iron at least, maybe some calcium).

Terraforming in another star system is problematic because it requires a lot of infrastructure. Terraforming in our own system is problematic enough; Mars would need something like 1e20 kg of an atmosphere, that it currently doesn't have, and you'd either have to import that sort of mass from elsewhere or liberate it from the regolith and both could be pretty difficult. Not impossible though; difficult.

But maybe it could be easier if the planet you wanted to terraform was easier target than Mars.

 

[fsci123]

Well if you realy wanted to start a good colony just send a whole bunch of random people and have them build from the natural resources...

Haha I described a natural colony...

 

[Eagle1Division]

What I'm most concerned with is what would the mass of the vessel be?
Would it be more mass-efficient to bring material to create cement and concrete to build homes, or just to bring habitats?

Something tells me with thousands of colonists necessary for a small civilization, you'd have to bring supplies to build homes rather than bringing homes. I like the idea of biologically "farming" polymers.

The world in mind have to be habitable, otherwise it would be pointless to travel interstellar distances to colonize it: If you're going into cryo for hundreds of years, you had might as well select a destination where the worst you'll need is an oxygen mask.

Perhaps it would be best to make a list on things to bring?:
1. Device to extract Deuterium from water.
2. Frozen bacteria to produce methane.
(For propelling orbital shuttles, to ferry people and supplies up and down from your interstellar vehicle)
3. Facilities with frozen bacteria to produce polymers (polymers used to build buildings and containers)
4. 3d Printers for parts.

So what would be necessary to create concrete, and cement? Maybe cement wouldn't be important at first, but you need steel to do anything. So what would you need to bring to create steel alloys? How could you bring an entire quarry and refinery along?

Could biologically produced polymers take the roles that you'd normally need steel for: That is, holding cryogenic liquids, working at temperature and pressure extremes, etc?

How would the shuttles land the first time, without runways? Maybe they'd have to be boat-planes, except in this case boat-spaceplanes.

 

[fsci123]

What I'm most concerned with is what would the mass of the vessel be?
Would it be more mass-efficient to bring material to create cement and concrete to build homes, or just to bring habitats?

Something tells me with thousands of colonists necessary for a small civilization, you'd have to bring supplies to build homes rather than bringing homes. I like the idea of biologically "farming" polymers.

The world in mind have to be habitable, otherwise it would be pointless to travel interstellar distances to colonize it: If you're going into cryo for hundreds of years, you had might as well select a destination where the worst you'll need is an oxygen mask.

Perhaps it would be best to make a list on things to bring?:
1. Device to extract Deuterium from water.
2. Frozen bacteria to produce methane.
(For propelling orbital shuttles, to ferry people and supplies up and down from your interstellar vehicle)
3. Facilities with frozen bacteria to produce polymers (polymers used to build buildings and containers)
4. 3d Printers for parts.

So what would be necessary to create concrete, and cement? Maybe cement wouldn't be important at first, but you need steel to do anything. So what would you need to bring to create steel alloys? How could you bring an entire quarry and refinery along?

Could biologically produced polymers take the roles that you'd normally need steel for: That is, holding cryogenic liquids, working at temperature and pressure extremes, etc?

How would the shuttles land the first time, without runways? Maybe they'd have to be boat-planes, except in this case boat-spaceplanes.

Bring habitats and factories first...
Before shuttles land send down a probe with some bombs to detonate a clean surface just like how they did in vietnam...

Well metal turns brittle at cryonic temps so does plastic...

Don't even think about cement it's a total waste of mass and time...

 

[T.Neo]

Mass is going to be heavily limited.

Most important will be:
- The 'autofactories'.
- The infrastructure needed to support the surface-to-orbit shuttles.
- Initial landers.
- Surface-to-orbit shuttles.
- Propellant for both.

How would the shuttles land the first time, without runways? Maybe they'd have to be boat-planes, except in this case boat-spaceplanes.

Since the shuttles will need at least some infrastructure to operate (fuel and propellant plants, runways), the best option would be to land a 'primary package' in some sort of vertical landing, one-way vehicle. This vehicle could contain the facilities necessary to establish a spaceport/airfield, and once disgorged of supplies and machinery, could become a temporary habitat/base of operations.

Then you could ship the remainder of supplies and people down to the surface using the shuttles and propellant/fuel manufactured on site.

Would it be more mass-efficient to bring material to create cement and concrete to build homes, or just to bring habitats?

You do not want to bring concrete and cement with you, if that's what you mean. Would impose a huge amount of mass.

But if you look at it this way; the mass of the equipment required to build a sturdy house, vs. the sturdy house itself.

Consider the fact that the construction equipment can be reused for hundreds, potentially thousands of sturdy houses, and it's a no-brainer, really.

A thousand sturdy houses would be a huge amount of mass for the vehicle to transport, but the equipment to make a thousand sturdy houses would be far less.

The world in mind have to be habitable, otherwise it would be pointless to travel interstellar distances to colonize it: If you're going into cryo for hundreds of years, you had might as well select a destination where the worst you'll need is an oxygen mask.

Hundreds of years is a bit long; you run into technical problems with the ship, and radioactivity tends to damage the humansicles (when you're alive, your body continuously repairs itself, but a frozen body is static and does not do so) over a long period of time. You can potentially solve the latter by rethawing people every few decades to help them recuperate from any damage, but this has problems as well (repeated freezing and thawing can't be a good thing).

You can constantly repair the ship, but this has problems, as a spacecraft can have very complex systems. The current limit for operations of space probes (as demonstrated by Voyager, etc) is maybe 40 years.

The other problem is spacecraft overtaking you. It's possible, but it depends on the general rate at which the capabilities of interstellar spacecraft increase. It could lead to a 'slowboat' arriving only to find that it has been beaten by faster STL ships.

12% of lightspeed will get you to Epsilon Eridani in just under 90 years, not accounting for acceleration and deceleration; this is the same top speed as that of Daedalus. Daedalus, however, did not have to decelerate at the target system, though a 'magnetic parachute' might be useful for reducing the amount of braking propellant needed.

Could biologically produced polymers take the roles that you'd normally need steel for: That is, holding cryogenic liquids, working at temperature and pressure extremes, etc?

I doubt it. Steel has strength and hardness and heat resistance that most plastics don't come close to. That's not to say you couldn't make many things out of plastics, but you'll probably need steel in there somewhere, even if it has to be shipped to the destination in the first instances.

So what would be necessary to create concrete, and cement? Maybe cement wouldn't be important at first, but you need steel to do anything. So what would you need to bring to create steel alloys? How could you bring an entire quarry and refinery along?

Probably a miniaturised steel foundry, along with means to get at and integrate the other elements needed for the planned alloys.

One answer to construction might be sintered regolith, though this is likely very energy-intensive.

The

I wonder if the steel rebar could, in this case, be replaced with some sort of plastic bracing structure(s).

Another concept I have personally wondered about for some time is a sort of plasti-crete, a composite material similar to concrete, with stone aggregate held together by a polymer 'glue'.

Before shuttles land send down a probe with some bombs to detonate a clean surface just like how they did in vietnam...

You're just looking for excuses to drop bombs on planets, aren't you, fsci?

It'd probably just be better to try and find an open area to land. If you need to at all; planets orbiting Epsilon Eridani could be subject to high rates of asteroidal bombardment, which could stifle any life present.

Well metal turns brittle at cryonic temps so does plastic...

If metal becomes so brittle at cryogenic temperatures, why doesn't the shuttle's external tank crack and shatter to a million pieces as it is being fueled on the launch pad?

 

[Eagle1Division]

Mass is going to be heavily limited.

Most important will be:
- The 'autofactories'.
- The infrastructure needed to support the surface-to-orbit shuttles.
- Initial landers.
- Surface-to-orbit shuttles.
- Propellant for both.

I like the idea of building a list...
And I like the idea of making it mostly comprehensive, so I'll add to it:
- Food
- Water
- Seeds
- Meat production unit (MPU :lol: - Vat-grown meat, very efficient)
- Medical supplies / facility (Doesn't include radiation sickness packages standard for cryo patients. Those are part of the ISV's hab. modules.)

I think the one-way landers should use small solid boosters. Despite the ludicrously low exhaust velocity, the ISV could place itself in a low orbit where only a tiny amount of Delta-Vee would be needed before the landers and pods re-enter, a Delta-Vee of only a hundred or so m/s would be necessary, and the advantage is the incredible reliability, simplicity, and shelf life of a solid booster, IMO beats out even a MMH/N204 thruster, which could have any number of issues during the multi-decade flight.

It's a one-shot engine, anyways. And while fuel lines, injectors, propellant tanks, valves, etc. etc. could fail on a liquid booster, a solid booster is just a candle - by far the most reliable way to get to the surface, at only a small cost in mass.

If you want a powered descent on your lander, though, that's a different story. But if the atmosphere is thick enough to breath, I want to assume it'll be thick enough for a parachute to do the job. And while parachutes are less accurate than a powered descent, you could include a steerable parachute if you really wanted precision.

Since the shuttles will need at least some infrastructure to operate (fuel and propellant plants, runways), the best option would be to land a 'primary package' in some sort of vertical landing, one-way vehicle. This vehicle could contain the facilities necessary to establish a spaceport/airfield, and once disgorged of supplies and machinery, could become a temporary habitat/base of operations.

Then you could ship the remainder of supplies and people down to the surface using the shuttles and propellant/fuel manufactured on site.

Wow... I really like that idea! . I've thought about drop/supply pods before, but then using them as temporary habitats/ bases of operation after is a great idea. But why temporary? They're already well insulated and may have ECLSS already installed. No reason they can't be permanent homes for the first colonists.

Question, though; how do you bring an airfield in a can? I take it you mean just supplies to make a flat, WWII-style airfield? I can't help but think there could be issues with this. What would be needed is a Fusion-powered shuttle like from the other thread, with the ruggedness of an AC-130. Water makes a more gentle airfield, though, granted it is more difficult to load/unload supplies and people.

You do not want to bring concrete and cement with you, if that's what you mean. Would impose a huge amount of mass.

But if you look at it this way; the mass of the equipment required to build a sturdy house, vs. the sturdy house itself.

Consider the fact that the construction equipment can be reused for hundreds, potentially thousands of sturdy houses, and it's a no-brainer, really.

A thousand sturdy houses would be a huge amount of mass for the vehicle to transport, but the equipment to make a thousand sturdy houses would be far less.

I wasn't talking about bringing concrete, lol. I meant more along the lines of bringing the equipment needed to make concrete. Though I think a better idea would be to use polymers and use the machine shops to make concrete-building equipment later on.

Hundreds of years is a bit long; you run into technical problems with the ship, and radioactivity tends to damage the humansicles (when you're alive, your body continuously repairs itself, but a frozen body is static and does not do so) over a long period of time. You can potentially solve the latter by rethawing people every few decades to help them recuperate from any damage, but this has problems as well (repeated freezing and thawing can't be a good thing).

You can constantly repair the ship, but this has problems, as a spacecraft can have very complex systems. The current limit for operations of space probes (as demonstrated by Voyager, etc) is maybe 40 years.

The other problem is spacecraft overtaking you. It's possible, but it depends on the general rate at which the capabilities of interstellar spacecraft increase. It could lead to a 'slowboat' arriving only to find that it has been beaten by faster STL ships.

12% of lightspeed will get you to Epsilon Eridani in just under 90 years, not accounting for acceleration and deceleration; this is the same top speed as that of Daedalus. Daedalus, however, did not have to decelerate at the target system, though a 'magnetic parachute' might be useful for reducing the amount of braking propellant needed.

I'm currently thinking of using MC-Fusion MAX, it has a much lower thrust power than anything else, and honestly I don't trust hundreds of moving parts (shock absorbing structure) to do their job for tens of years without a single failure. Imagine if the launch vibrations for any rocket lasted for months, or even years. Now that's "shaking and baking the hardware".

A magnetic parachute sounds nice, but doesn't it require electrical power?

As for ship damage, I'd design it so that it works with large margins of error, to give it some ruggedness. A good example is the B-17, maybe not that rugged, but you get the point. I think SpaceX is also doing something like this to decrease costs. Ship will be a bit more massive, but increased reliability is well worth it. Larger margins of error is a passive system, having to repair the ship en-route is active.

And even though cryonics is in it's infancy, if you can even call it alive yet, I think we should assume waking them up and freezing again is either impossible or just a bad idea in general. It's a lot easier to build the ISV when the ECLSS requirements are only for a day or so of manned operation, not days, weeks, months, or years.

I doubt it. Steel has strength and hardness and heat resistance that most plastics don't come close to. That's not to say you couldn't make many things out of plastics, but you'll probably need steel in there somewhere, even if it has to be shipped to the destination in the first instances.

What I'm thinking of is tanks, pipes, valves, etc. for creating the cryogenic methane fuel, handling cryogenic liquids, producing electrical power (which almost always involves lots of heat), etc.


Speaking of electrical power, electrical power makes the world go round, so to speak. So what's the solution here? I'm thinking RTG's to power the initial infrastructure, and a nuclear reactor (fission). Use the RTG's to power everything until you can build a powerplant to put the reactor in.

RTG's would have barely enough power to get by until the nuclear powerplant is built.

I wouldn't bring solar panels, since those rely on a number of things. They rely on a certain thickness of atmosphere, a certain day/night cycle, and would probably weigh more than RTG's.

One option where I would consider them is to put them on the ISV, and have the ISV beam down power, though I still like RTG's better than this option.

Other option is a fusion powerplant, but those are far more complex, and less durable/rugged than a simple fission reactor. Not to mention by building the structure part of the fission reactor on-site, it'll probably be lighter than the fusion plant, where you'd have to bring the whole thing along.

True that there's radiation involved when dealing with a fission powerplant, but remote or even automated equipment could do the work near the reactor core.

I'd seriously consider bringing robots, that is, human-like ones, because of the sheer number of different tasks they could do. Including construction in the radioactive danger zone of the reactor.

Once the colony is well established and the infrastructure is past it's infancy, then they can consider less rugged systems like a fusion powerplant.

Probably a miniaturised steel foundry, along with means to get at and integrate the other elements needed for the planned alloys.

One answer to construction might be sintered regolith, though this is likely very energy-intensive.

The Dymaxion house is an interesting concept, but is constructed out of energy-intensive aluminium (this has been one of the criticisms of the Dymaxion house; the rationale behind the use of aluminium was the abundance of aluminium-working facilities in the wake of WWII- aircraft factories). Maybe such a structure could be constructed out of a polymer instead.

Another option is the monolithic dome. It requires concrete and rebar, but is very sturdy and durable, and allows for good climate control. It could also potentially be regarded as relatively easy to construct.

This video advertises some of the advantages of monolithic domes:
Introduction to Monolithic Domes

I wonder if the steel rebar could, in this case, be replaced with some sort of plastic bracing structure(s).

Another concept I have personally wondered about for some time is a sort of plasti-crete, a composite material similar to concrete, with stone aggregate held together by a polymer 'glue'.

A way one could probably cut back on the labor required massively would be if some polymer alone could handle the job, like if the only part required was inflating the dome then spraying on a foam-like material, then spraying on a polymer that's strong and stiff enough to take the job of the rebar concrete.

(Wait... That's what you said, isn't it? lol.)

I don't know how the foam is produced, but anything that can be biologically farmed in vats is going to be a huge bonus, I'd want to use as many of those materials as possible. The domes would probably be very low mass, though, and a few could probably be brought along for initial stages of construction.
The Inflatable domes, that is.

Btw, T.Neo... Monolithic domes? Dymaxion house? Add that to armchair biology and rocket engineering, have you ever considered taking the place of living Encyclapedia at a university?

 

[nygiantsrob]

...Concern Number One Is Power ...Without That None Of The Rest Will ...& Obviously It Can't Be Anything Too Hi-tech ...Simple Technology, Preferably Renewable, Like Hydro Would Work I Think ...

Sent from my T-Mobile myTouch 3G using Tapatalk

 

[T.Neo]

I like the idea of building a list...
And I like the idea of making it mostly comprehensive, so I'll add to it:
- Food
- Water
- Seeds
- Meat production unit (MPU - Vat-grown meat, very efficient)
- Medical supplies / facility (Doesn't include radiation sickness packages standard for cryo patients. Those are part of the ISV's hab. modules.)

Ah yes! Vat grown meat, good idea.

There'll be none of those pansy hippie greenie veggie colonists here, no sir. :rofl:

All of those things might end up having a negligible amount of mass compared to the rest of the stuff being brought down to the surface. I'd include stuff like hydroponics equipment, for example, but a large part of that infrastructure will likely be constructed in-situ using the autofactories.

But you will need food supplies, for the time period until your food production facilities get up to speed. And medical stuff is indeed a problem; you've got only so much, and you can't really make more unless you have decent facilities.

But why temporary? They're already well insulated and may have ECLSS already installed. No reason they can't be permanent homes for the first colonists.

I just assumed that after a while they'd want to move into something slightly more substantial, but if the facilities are good enough, why not?

It's a one-shot engine, anyways. And while fuel lines, injectors, propellant tanks, valves, etc. etc. could fail on a liquid booster, a solid booster is just a candle - by far the most reliable way to get to the surface, at only a small cost in mass.

Not quite. Remember, you have deorbit, and then you have landing. And this is no Mars lander, no Soyuz slightly braking its parachute descent moments before hitting the ground. You're talking tens, maybe even a hundred tons or more of infrastructure falling out of the sky. Pretty much the only way to prevent it from going splat is going to be by using considerable rockets. You'll have to throttle them, gimbal them... essentially, it would be the landing sequence of something like the DC-X (though of course, it would be one-way).

Though I think a better idea would be to use polymers and use the machine shops to make concrete-building equipment later on.

Keep in mind though that you still have to transport your polymer-making equipment...

I'm currently thinking of using MC-Fusion MAX, it has a much lower thrust power than anything else, and honestly I don't trust hundreds of moving parts (shock absorbing structure) to do their job for tens of years without a single failure. Imagine if the launch vibrations for any rocket lasted for months, or even years. Now that's "shaking and baking the hardware".

Daedalus isn't Orion. The pulse rate is much higher, so the ride is smoother. Daedalus dealt with essentially the same thrust issues as this vehicle; thrusting for nearly four years before getting to cruise velocity. It was quite a lightweight design, too. Certainly for its size (a comparison with the STS/Saturn stack is really scary).

MC fusion will have a far lower specific power than Daedalus-style IC fusion. That means (potentially much) lower acceleration, and that means a longer travel time.

A magnetic parachute sounds nice, but doesn't it require electrical power?

Yes, but since it uses the interstellar medium to brake the ship, the ship doesn't have to carry its own propellant, and that is very important.

But it will likely become less effective as velocity decreases, which means that a rocket engine will likely be required to perform the final deceleration burn. Hopefully by then most of the velocity will be shaved off however, so that the craft doesn't end up massing 12 million tons or somesuch.

As for ship damage, I'd design it so that it works with large margins of error, to give it some ruggedness. A good example is the B-17, maybe not that rugged, but you get the point. I think SpaceX is also doing something like this to decrease costs. Ship will be a bit more massive, but increased reliability is well worth it. Larger margins of error is a passive system, having to repair the ship en-route is active.

It will help, but it won't entirely solve the problem. For example, computers, cosmic rays... over timescales of hundreds of years, that could be particularly damaging.

It's a lot easier to build the ISV when the ECLSS requirements are only for a day or so of manned operation, not days, weeks, months, or years.

Unloading hundreds to thousands (depends on how many ships are in your colonisation effort) will likely take more than a day; probably more than a week. It might even take a few months; during which time some of the crew would be active, as more and more people would be revived, ready for their trips to the surface.

What I'm thinking of is tanks, pipes, valves, etc. for creating the cryogenic methane fuel, handling cryogenic liquids, producing electrical power (which almost always involves lots of heat), etc.

Maybe it's possible, probably depends on what polymer you use. I don't know.

Speaking of electrical power, electrical power makes the world go round, so to speak. So what's the solution here? I'm thinking RTG's to power the initial infrastructure, and a nuclear reactor (fission). Use the RTG's to power everything until you can build a powerplant to put the reactor in.

RTGs are a bad idea. Not only do they provide a very small amount of power, but their power output drops with time (as does all radioactivity). After an 80-100 year trip, they could be more-or-less useless.

For startup power the best option would probably be a small fission reactor (like the ones being studied for power on interplanetary vehicles and surface bases), inactive during the trip, so it isn't radioactive, and then using local materials (dirt) for some shielding. That could get the colony by for a bit until you can refine deuterium, which you're going to need for your spaceplanes anyway.

And you can burn that deuterium in a reactor (you've perfected fusion technology; you've got a fleet of fusion powered shuttles and an interstellar spacecraft, so this is obvious) on the ground. Even a gigawatt output station is quite big; the shuttles are putting out multiple gigawatts from amazingly small engines, though that is only for a few minutes. It should be easy enough to have a moderately-massed fusion reactor outputting far less (but still a considerable amount of) power, perhaps on the order of several hundred megawatts, which could easily power the nascent colony.

A fusion reactor produces no radioactive waste in the same sense that a fission reactor does, and although D-D reactions do produce tritium, this can potentially be re-cycled as it is good fusion fuel itself.

The reactor should not require that much deuterium, but whether it is viable depends on how much deuterium can be extracted, and at what rate.

I wouldn't bring solar panels, since those rely on a number of things. They rely on a certain thickness of atmosphere, a certain day/night cycle, and would probably weigh more than RTG's.

One option where I would consider them is to put them on the ISV, and have the ISV beam down power, though I still like RTG's better than this option.

"Beamed power" makes me think "lazah beamz!!!11!!1!!"

Which makes me kinda scared. :shifty:

In addition, unless the ISV is in geosynch (which will be far away), it'll be constantly moving from the point of the colony and only fly over a fraction of the time, and thus would be worse to rely on than solar power.

Other option is a fusion powerplant, but those are far more complex, and less durable/rugged than a simple fission reactor. Not to mention by building the structure part of the fission reactor on-site, it'll probably be lighter than the fusion plant, where you'd have to bring the whole thing along.

You're operating fusion shuttles!

And you can potentially build parts of the fusion reactor in-situ, you can use in-situ materials. It's just the really complex science-y bits. But for example the shielding or the cooling system could potentially be local.

In terms of having mass shipped to the base, a fission reactor's 'science-y bits' are probably just as bad. In addition, you'll have to carry all your fuel with you, whereas a fusion reactor would utilise the same fuel source as that of the spaceplanes.

Granted, a fission reactor could run for several decades.

I'd seriously consider bringing robots, that is, human-like ones, because of the sheer number of different tasks they could do. Including construction in the radioactive danger zone of the reactor.

Human-like? Why?

I can think of several robotics applications in this environment where a human-like form would not be a good idea. Granted, maybe the humanoid form could have a degree of universality to it, but there are certain applications that it arguably wouldn't do very well and would be too fragile/unstable/weak for.

Working inside the radiation-filled reactor is one thing, but how often do you see humans working inside the radiation-filled areas of nuclear reactors on Earth?

Edit: ATHLETE comes to mind, can manipulate, and carry stuff or even people, can traverse various types of terrain, relatively heavy duty, relatively versatile.

Once the colony is well established and the infrastructure is past it's infancy, then they can consider less rugged systems like a fusion powerplant.

You're operating fusion spaceplanes!

A way one could probably cut back on the labor required massively would be if some polymer alone could handle the job, like if the only part required was inflating the dome then spraying on a foam-like material, then spraying on a polymer that's strong and stiff enough to take the job of the rebar concrete.

(Wait... That's what you said, isn't it? lol.)

I don't know how the foam is produced, but anything that can be biologically farmed in vats is going to be a huge bonus, I'd want to use as many of those materials as possible. The domes would probably be very low mass, though, and a few could probably be brought along for initial stages of construction.

Bio-foam? That'd be interesting.

You might end up using 'nanotechnology'. You're already talking about it, in fact- bacteria are pretty much 'nanomachines', plus they're ones that have existed for billions of years and have all sorts of nifty features. Maybe you could engineer a strain of bacteria to do something particularly interesting.

There is this:

Though I doubt its durability matches that of a monolithic dome, or even a conventional brick structure for that matter. In addition those styrofoam parts don't just come from nowhere; they have to be moulded somewhere.

Maybe there is some way to create a monolithic polymer dome. I mean, if you think of how biological materials such as wood and horn are relatively strong and relatively lightweight, it could be easy to imagine some sort of tough, high tensile strength polymer replacing rebar in a monolithic dome, with concrete replaced with a kind of polymer, or a plastic-crete using broken up local rock as aggregate.

 

[Eagle1Division]

Ah yes! Vat grown meat, good idea.

There'll be none of those pansy hippie greenie veggie colonists here, no sir. :rofl:

Lol. Vat-grown meat is just as efficient as crops... Think of it as a healthy, iron-rich, juicy multivitamin.

All of those things might end up having a negligible amount of mass compared to the rest of the stuff being brought down to the surface. I'd include stuff like hydroponics equipment, for example, but a large part of that infrastructure will likely be constructed in-situ using the autofactories.

But you will need food supplies, for the time period until your food production facilities get up to speed. And medical stuff is indeed a problem; you've got only so much, and you can't really make more unless you have decent facilities.

I think food and water might be somewhat significant, given it might be awhile before Aeroponic farms get up to full production.

Not quite. Remember, you have deorbit, and then you have landing. And this is no Mars lander, no Soyuz slightly braking its parachute descent moments before hitting the ground. You're talking tens, maybe even a hundred tons or more of infrastructure falling out of the sky. Pretty much the only way to prevent it from going splat is going to be by using considerable rockets. You'll have to throttle them, gimbal them... essentially, it would be the landing sequence of something like the DC-X (though of course, it would be one-way).

The space shuttle SRB's each way 100 tons and manage to work with just parachutes. Granted, they do splash-down. One argument I can see against parachutes though is that the atmospheric thickness isn't perfectly certain, while descent rockets are. I think a good idea would be a combination of the two, parachutes to make the descent very slow, and rockets to kill whatever excess velocity is left.

This way, if either system fails, there will be heavy damage but it will be more than a heap of ruined metal. And, the rockets don't need to be really heavy, so overall it's lighter, too.

I would add 2 cameras, a laser pointer, and a small computer. Cameras use parallax to determine distance to the laser point, this way it could land on any surface with extreme accuracy in distance readings (Radar or straight-out using a laser isn't always accurate), glides using a parachute then a small blast of rocket slows it down to a safe speed once it's very close to the ground.

Once in-orbit and enough data is gathered about the planet, things like atmospheric pressure can be used to get a rough altitude reading, to determine when to deploy the parachutes.

Keep in mind though that you still have to transport your polymer-making equipment...

Invariably, I think we're agreed that it's important enough to bring, though.

Daedalus isn't Orion. The pulse rate is much higher, so the ride is smoother. Daedalus dealt with essentially the same thrust issues as this vehicle; thrusting for nearly four years before getting to cruise velocity. It was quite a lightweight design, too. Certainly for its size (a comparison with the STS/Saturn stack is really scary).

MC fusion will have a far lower specific power than Daedalus-style IC fusion. That means (potentially much) lower acceleration, and that means a longer travel time.

Not according to the engine list...

IC-Fusion MAX:
Thrust Power (GW):
500,000
Exhaust Velocity (m/s):
10,000,000
Thrust (N):
100,000,000
Mass (tons):
1000

MC-Fusion MAX:
Thrust Power (GW):
200
Exhaust Velocity (m/s):
8,000,000
Thrust (N):
50,000
Mass (tons):
0.6

MCF Ve:
8,000,000
ICF Ve:
10,000,000

MCF offers lower thrust and exhaust velocity, but is also more than a thousand times lighter. I would also consider it more reliable... It's the ICF part about having to launch a pellet every time, and having to hit the pellet with lasers perfectly, thousands of times. If a single part of it messes up a little, the lasers will blow the engine apart. It's a nice engine set up, but it seems too "active" to me, like too many things have to happen exactly right every time hundreds if not thousands of times, all automatically.

Meanwhile all the movement in a MCF engine is electrical, aside from Deuterium injection. But Deuterium is a fluid (gas or liquid), ICF pellets are solid. Pumps are very reliable, but guns jam. You would need the ICF system to have the reliability of a Vicker's Machine gun, and the high mass of the system might actually compromise the added impulse by reducing the mass ratio. That calculation will have to hold off until we can start designing the vehicle, though, once we know what mass we're bringing...

The biggest reason I'm looking to use MCF engines though is because they're so much smaller, and will allow for the ship to be better designed in a pull configuration and include staged fuel tanks along the truss, where it would be more difficult to design the same thing using ICF, and would require more mass, not to mention a much stronger truss to take the added acceleration, which also adds weight.

And if it's not using massive shock absorbers like Orion, then I'd consider it even less reliable since the entire structure will have to take the shock loads.

Yes, but since it uses the interstellar medium to brake the ship, the ship doesn't have to carry its own propellant, and that is very important.

But it will likely become less effective as velocity decreases, which means that a rocket engine will likely be required to perform the final deceleration burn. Hopefully by then most of the velocity will be shaved off however, so that the craft doesn't end up massing 12 million tons or somesuch.

Now if only we could find the math for the power required for a certain effectiveness...

It will help, but it won't entirely solve the problem. For example, computers, cosmic rays... over timescales of hundreds of years, that could be particularly damaging.

I remember that computers can be built to withstand more radiation than others. In particular I think satellites use more radiation-rugged computers. Especially ones in semi-synchranous orbits that pass the Van Allen belt a lot.

Unloading hundreds to thousands (depends on how many ships are in your colonisation effort) will likely take more than a day; probably more than a week. It might even take a few months; during which time some of the crew would be active, as more and more people would be revived, ready for their trips to the surface.

Ah, so this brings us to the question of how many colonists?

RTGs are a bad idea. Not only do they provide a very small amount of power, but their power output drops with time (as does all radioactivity). After an 80-100 year trip, they could be more-or-less useless.

For startup power the best option would probably be a small fission reactor (like the ones being studied for power on interplanetary vehicles and surface bases), inactive during the trip, so it isn't radioactive, and then using local materials (dirt) for some shielding. That could get the colony by for a bit until you can refine deuterium, which you're going to need for your spaceplanes anyway.

And you can burn that deuterium in a reactor (you've perfected fusion technology; you've got a fleet of fusion powered shuttles and an interstellar spacecraft, so this is obvious) on the ground. Even a gigawatt output station is quite big; the shuttles are putting out multiple gigawatts from amazingly small engines, though that is only for a few minutes. It should be easy enough to have a moderately-massed fusion reactor outputting far less (but still a considerable amount of) power, perhaps on the order of several hundred megawatts, which could easily power the nascent colony.

A fusion reactor produces no radioactive waste in the same sense that a fission reactor does, and although D-D reactions do produce tritium, this can potentially be re-cycled as it is good fusion fuel itself.

The reactor should not require that much deuterium, but whether it is viable depends on how much deuterium can be extracted, and at what rate.

I'm pretty sure fission reactors are radioactive even when they're off; as long as they've got the fissible materials inside, even if the radiation is blocked, it's still there...

I think I like that idea, best, though. Since fission reactors are so much simpler and don't require constant feeding of Deuterium, a small spaceship-sized reactor would be great until the deuterium propellant plants are online.

You're operating fusion shuttles!

And you can potentially build parts of the fusion reactor in-situ, you can use in-situ materials. It's just the really complex science-y bits. But for example the shielding or the cooling system could potentially be local.

In terms of having mass shipped to the base, a fission reactor's 'science-y bits' are probably just as bad. In addition, you'll have to carry all your fuel with you, whereas a fusion reactor would utilise the same fuel source as that of the spaceplanes.

Granted, a fission reactor could run for several decades.

Fission reactor runs until Deuterium processing plants are online.

Bio-foam? That'd be interesting.

You might end up using 'nanotechnology'. You're already talking about it, in fact- bacteria are pretty much 'nanomachines', plus they're ones that have existed for billions of years and have all sorts of nifty features. Maybe you could engineer a strain of bacteria to do something particularly interesting.

There is this:
Styrofoam dome home

Though I doubt its durability matches that of a monolithic dome, or even a conventional brick structure for that matter. In addition those styrofoam parts don't just come from nowhere; they have to be moulded somewhere.

Maybe there is some way to create a monolithic polymer dome. I mean, if you think of how biological materials such as wood and horn are relatively strong and relatively lightweight, it could be easy to imagine some sort of tough, high tensile strength polymer replacing rebar in a monolithic dome, with concrete replaced with a kind of polymer, or a plastic-crete using broken up local rock as aggregate.

I'm hesitant to use the word "nano", since that seems to almost be a buzzword. But it is sort of nanotech in a sense, but I think it'd be more accurate to call it "bio". IIRC, I think bacteria are already being used to to breed some types of fuel.

Only in this case, they'd be used to create large amounts of construction material. They could probably be made to "grow" it in the same way that horns or fingernails grow.

Maybe the material could even be something very similar to wood.

EDIT:
Let's not forget the list:

1- The 'autofactories'.
2- Surface-to-orbit shuttles.
3- Initial landers:
3a- - Airfield Package
3aa- - - The infrastructure needed to support the surface-to-orbit shuttles.
3ab- - - Deuterium extraction unit and tanks.
3ac- - - Methane breeding and liquid storage tanks.
3b- - Food
3c- - Water
3d- - Aeroponics Facility
3e- - Fission Powerplant
3f- - Medical supplies / facility
3g- - Material Production facility (farms construction materials, liquid polymers for spraying inside domes and building foundations)
3h- - Construction Materials
3ha- - - Fans (to inflate dome), Domes, suits, foundation digger.
4- Fusion Powerplant

I would want something about the size and weight of a forklift (well, minus the weight. Forklifts aren't built light, but you could build one light if you needed, like in this case) to dig the foundation, and save a lot of time and labor by using it. It might also be able to pour the foundation, the same liquid polymer that's already taken the place of cement. This vehicle would be the foundation digger.

 

[T.Neo]

Lol. Vat-grown meat is just as efficient as crops... Think of it as a healthy, iron-rich, juicy multivitamin.

Well, it's less efficient than crops, because even though it's only a pile of cells and not a distint animal, it's still a heterotroph, as opposed to being an autotroph (like a crop, converting abundant elements and sunlight to energy). You still have to "feed" the meat nutrients for it to grow.

But it's still far more efficient than raising entire animals.

I think food and water might be somewhat significant, given it might be awhile before Aeroponic farms get up to full production.

What are the specific advantages for aeroponics over hydroponics?

Not according to the engine list...

Ah yes, the 600 kg fusion engine...

My insistance on the Daedalus figures and my skepticism come from the fact that there is (relatively) considerable data for Daedalus on the web, but the 600 kg MCF engine figure is one figure on one website.

If you can find more data on such high performance engines, I'd be very, very appreciative.

And if it's not using massive shock absorbers like Orion, then I'd consider it even less reliable since the entire structure will have to take the shock loads.

It doesn't have to deal with such severe shock loads. I think. It'll have to deal with vibration along with the pulse rate, but it shouldn't have to worry about Orion-like forces.

If you need to, you could easily have some sort of buffer to deal with vibration; it would likely not need to be as massive and complex as that of Orion.

Now if only we could find the math for the power required for a certain effectiveness...

I'm sure the math is out there, not sure where though.

I remember that computers can be built to withstand more radiation than others. In particular I think satellites use more radiation-rugged computers. Especially ones in semi-synchranous orbits that pass the Van Allen belt a lot.

Oh, of course you'd be using radiation resistant computers, but not even those are invulnerable, especially over long timescales.

Ah, so this brings us to the question of how many colonists?

That is a very good question. In terms of genetics, all of humanity are likely descended from a genetic bottleneck of some 10 000 people, the survivors of the climatic effects of a supervolcano eruption. However, there may be other situations (such as during the Polynesian colonisation of the Pacific) where smaller populations still lead to a suitable population. But 10 000 is a safe bet, genetically. 100 000 might be better in terms of having a logistically sound society, but you could potentially get off with less by using advanced technology.

I'm pretty sure fission reactors are radioactive even when they're off; as long as they've got the fissible materials inside, even if the radiation is blocked, it's still there...

I've heard that a uranium-fueled reactor, at least, is not (that) radioactive before it has been activated for the first time (the only radioactivity is that from the uranium decay).

I'm hesitant to use the word "nano", since that seems to almost be a buzzword. But it is sort of nanotech in a sense, but I think it'd be more accurate to call it "bio". IIRC, I think bacteria are already being used to to breed some types of fuel.

Yeah, "nano" is a total buzzword in science fiction today. It's used for practically everything under the Sun and I have a feeling that, to be honest, it just ends up being magical and not tied to any technology at all, real or speculative.

Radio became influential, but radio clocks? Radio powered roller skates? Seriously?

Biotech would be more appropriate. Biotech is pretty common in science fiction (in the 'iv got bionic spaseships lulz' sort of sense), but actual biotechnology, sorts of biological systems that do a lot of the jobs you'd see "nanotechnology" do and doesn't amount to magic, that is quite rare.

Concievably bacteria would be at least our first approximations of the drexlerian "nanomachine". But they'd have realistic limitations, of course; the explanation behind a bucket of goo that you just tap some numbers into and then throw into a pile of dirt, to produce a flawless spacecraft in anywhere from minutes to weeks/months (depending on sf 'hardness' factor) completely and absolutely dumbfounds me.

Fermenting biomass to make methane fuel is pretty simple, and we've been using microorganisms (yeast) to make bread and beer for thousands of years.

And let's face it: "nano" is a silly world.

Only in this case, they'd be used to create large amounts of construction material. They could probably be made to "grow" it in the same way that horns or fingernails grow.

Maybe the material could even be something very similar to wood.

Yes, that'd probably be a good approximation of it. Horn and wood grow as part of genetically predetermined organisms, a vat of bacteria would be producing an amorphous blob of material. Unless you engineer the organism to create specific shape(s), which would be a whole other kettle of... bacteria.

But that would be interesting, a specific, genetically engineered plant(s) or other organism, that would grow into a dwelling or at least part of a dwelling, if in the right environment. It'd be quite intensive from a genetic engineering point of view (likely more so than just getting bacteria to create some sort of strong polymer material), but it'd make for an interesting concept nontheless.

 

[Eagle1Division]

Well, it's less efficient than crops, because even though it's only a pile of cells and not a distint animal, it's still a heterotroph, as opposed to being an autotroph (like a crop, converting abundant elements and sunlight to energy). You still have to "feed" the meat nutrients for it to grow.

But it's still far more efficient than raising entire animals.

I think diet has a surprisingly strong influence on a society, after all, an entire society is nothing but the cumulation of many individuals' days.

i.e., Something to add variety and spice up the diet would really help morale.

What are the specific advantages for aeroponics over hydroponics?

IIRC, it's less rescource-intensive and grows faster. I'm not a 100% on the second part, but it certainly does use a lot less water.

Ah yes, the 600 kg fusion engine...

My insistance on the Daedalus figures and my skepticism come from the fact that there is (relatively) considerable data for Daedalus on the web, but the 600 kg MCF engine figure is one figure on one website.

If you can find more data on such high performance engines, I'd be very, very appreciative.

I have a feeling the 600 kg figure came from the actual test model that was built at the Marshall Space Flight Center, the Gas Dynamic Mirror Fusion Propulsion System:
Link1
Link2
Link3
The GDM only produced an Isp of 130,000 seconds (~1,274,000 m/s).

If you want a less dreamy number, that's 1/6th the impulse of the MAX figure. So, for a pseudo-science sort of way of getting a number, you could either multiply the mass by 6 or 36.
3,600 kg or 21,600 kg.

Hey... It's better than pulling a number out of the air... Even though that's sort of what it is...

It doesn't have to deal with such severe shock loads. I think. It'll have to deal with vibration along with the pulse rate, but it shouldn't have to worry about Orion-like forces.

If you need to, you could easily have some sort of buffer to deal with vibration; it would likely not need to be as massive and complex as that of Orion.

I'll be a hard sell on this. Vibrations; like I said earlier. Many things go wrong during the few seconds of launch vibrations that the shuttle and other vehicles experience. Do it over weeks, months, or years...
And then if you add shock absorbers to get rid of the vibrations, you end up with shock absorbers that have to function perfectly for roughly a hundred years under constant use.

That is a very good question. In terms of genetics, all of humanity are likely descended from a genetic bottleneck of some 10 000 people, the survivors of the climatic effects of a supervolcano eruption. However, there may be other situations (such as during the Polynesian colonisation of the Pacific) where smaller populations still lead to a suitable population. But 10 000 is a safe bet, genetically. 100 000 might be better in terms of having a logistically sound society, but you could potentially get off with less by using advanced technology.

You could bring less colonists than what's genetically necessary, and bring the genetically necessary number in the form of unborn embryos, or even single cell or cell clusters.

Yeah, "nano" is a total buzzword in science fiction today. It's used for practically everything under the Sun and I have a feeling that, to be honest, it just ends up being magical and not tied to any technology at all, real or speculative.

Radio became influential, but radio clocks? Radio powered roller skates? Seriously?

Biotech would be more appropriate. Biotech is pretty common in science fiction (in the 'iv got bionic spaseships lulz' sort of sense), but actual biotechnology, sorts of biological systems that do a lot of the jobs you'd see "nanotechnology" do and doesn't amount to magic, that is quite rare.

Concievably bacteria would be at least our first approximations of the drexlerian "nanomachine". But they'd have realistic limitations, of course; the explanation behind a bucket of goo that you just tap some numbers into and then throw into a pile of dirt, to produce a flawless spacecraft in anywhere from minutes to weeks/months (depending on sf 'hardness' factor) completely and absolutely dumbfounds me.

Fermenting biomass to make methane fuel is pretty simple, and we've been using microorganisms (yeast) to make bread and beer for thousands of years.

And let's face it: "nano" is a silly world.

Yes, that'd probably be a good approximation of it. Horn and wood grow as part of genetically predetermined organisms, a vat of bacteria would be producing an amorphous blob of material. Unless you engineer the organism to create specific shape(s), which would be a whole other kettle of... bacteria.

But that would be interesting, a specific, genetically engineered plant(s) or other organism, that would grow into a dwelling or at least part of a dwelling, if in the right environment. It'd be quite intensive from a genetic engineering point of view (likely more so than just getting bacteria to create some sort of strong polymer material), but it'd make for an interesting concept nontheless.

Growing dwellings from seeds is interesting, but probably very time intensive, just using trees as an example.

As for farming materials, I imagine that it'd be large racks of a biological goo (a large colony of genetically engineered microorganisms), fed light, warmth, and maybe some nutrient-water, the colony drips a liquid; a polymer that takes the role of cement, it drips into a large mixer where it's stored and used like cement.

Another alternative is sheets of biomass that "grows" keratin-rich cells with cell walls, so you'd essentially be growing sheets of wood. Or horn biomass. Depending on how you look at it...

Polymer idea is more attractive, though, since it's liquid and can be sprayed to construct monolithic domes.

 

[T.Neo]

I think diet has a surprisingly strong influence on a society, after all, an entire society is nothing but the cumulation of many individuals' days.

i.e., Something to add variety and spice up the diet would really help morale.

Oh no, I definitely agree. It'd be pretty mean to send thousands of people to another star system with only spirulina and soy for food...

What about raising fish and/or various types of shellfish?

IIRC, it's less rescource-intensive and grows faster. I'm not a 100% on the second part, but it certainly does use a lot less water.

Fair enough. How does it compare to hydroponics in terms of number of crops proven to be growable in that manner?

I have a feeling the 600 kg figure came from the actual test model that was built at the Marshall Space Flight Center, the Gas Dynamic Mirror Fusion Propulsion System:
Link1
Link2
Link3
The GDM only produced an Isp of 130,000 seconds (~1,274,000 m/s).

If you want a less dreamy number, that's 1/6th the impulse of the MAX figure. So, for a pseudo-science sort of way of getting a number, you could either multiply the mass by 6 or 36.
3,600 kg or 21,600 kg.

Hey... It's better than pulling a number out of the air... Even though that's sort of what it is...

I pull numbers out of the air too, sometimes. :shifty:

What does "actual test model" actually mean with regard to fusion propulsion, since we cannot even build a breakeven fusion powerplant?

Since a gasdynamic fusion engine would pretty much look like that on this craft:

I can't imagine it would be all that light.

If we divide 200 gigawatts by 600 kg, we get a specific power of over 333 000 kW/kg. If we calculate Daedalus' first stage thrust power to be roughly 39 terawatts, and we use the mass of the first stage as the engine mass (the engine only takes up a part of the mass, I know, I know), then we get a specific power of roughly 23 650 kW/kg. Which is comparable to the gasdynamic fusion figures, so maybe they are not absurd.

But whether those numbers could be reached in reality probably depends on whether the mass of the magnets and the cooling system can be crammed into that mass figure (unless the radiators aren't included, for whatever reason).

But: The very first page of this document that you link to states a specific power figure of 10 kW/kg, which is in standing with the various other numbers I have seen for more near-future concepts. The problem is that such a figure is far too low for meaningful interstellar travel. At that rate, a 200 gigawatt drive would mass 20 000 tons, a 2 terawatt drive 200 000 tons, and a 20 terawatt drive 2 000 000 tons. Entirely impractical.

I'll be a hard sell on this. Vibrations; like I said earlier. Many things go wrong during the few seconds of launch vibrations that the shuttle and other vehicles experience. Do it over weeks, months, or years...
And then if you add shock absorbers to get rid of the vibrations, you end up with shock absorbers that have to function perfectly for roughly a hundred years under constant use.

An engine running for roughly a century? Project Daedalus only accelerated for roughly four years!

One can easily imagine such an engine breaking down over such a timescale, regardless of type...

The vibrations on Daedalus never tore the ship apart, or at least the designers didn't think they would.

If you have to add dampeners, they don't have to be shock absorbers, as with an Orion that actually does nuke itself over and over. They could for example be flexible struts, or springs, designed to dampen the force of vibration. Moving parts, yes, but not terribly unreliable.

Unless you're running them for a hundred years or more. :uhh:

You could bring less colonists than what's genetically necessary, and bring the genetically necessary number in the form of unborn embryos, or even single cell or cell clusters.

And turn the women into babymaking machines. :dry:

Remember that the nascent colony also needs a fair amount of manpower to get going, even with advanced technology.

Growing dwellings from seeds is interesting, but probably very time intensive, just using trees as an example.

As for farming materials, I imagine that it'd be large racks of a biological goo (a large colony of genetically engineered microorganisms), fed light, warmth, and maybe some nutrient-water, the colony drips a liquid; a polymer that takes the role of cement, it drips into a large mixer where it's stored and used like cement.

Another alternative is sheets of biomass that "grows" keratin-rich cells with cell walls, so you'd essentially be growing sheets of wood. Or horn biomass. Depending on how you look at it...

Polymer idea is more attractive, though, since it's liquid and can be sprayed to construct monolithic domes.

Yeah, the problem with the tree-house thing is that it'd probably be impractical on this timescale. Maybe elsewhere though, somewhere, somehow.

You really want to try and culture proper polymers, rather than stuff like keratin (which has various limitations and impracticalities). Then again, stuff like chitin and cellulose are polymers. Cellulose only contains hydrogen, carbon and oxygen, which might be a bonus.

It's still viable even if your bacteria produce the compounds that polymers can be synthesised from. In fact, that'd likely be far easier to attempt than creating actual 'plastics' using bacteria.

But biological stuff like 'horn' or 'wood' are still interesting options. If you can grow and shape them, they'll be easier to deal with than plastics that have to be made via an artificial process using bacterial feedstock, etc.

 

[Eagle1Division]

Oh no, I definitely agree. It'd be pretty mean to send thousands of people to another star system with only spirulina and soy for food...

What about raising fish and/or various types of shellfish?

Fish farming is still less efficient than vat meating. I'd just use different types of meat. Though it'd probably have a different texture.

Hmm, here we are discussing colonization of the first exoplanet, interstellar spacecraft propulsion and building a small civilization... And we're discussing eating fish? I like it. :lol:

Fair enough. How does it compare to hydroponics in terms of number of crops proven to be growable in that manner?

To be honest It's been quiet awhile since I've read up on it. But from what I understand, it's disease-free, makes healthier plants, and is more dense per volume and mass, not to mention far more efficient in terms of water use. It's also been the target of lots of NASA studying, and has been carried aboard/conducted on the Shuttle and Mir, at least.
http://en.wikipedia.org/wiki/Aeroponics#Large_scale_integration_of_aeroponics

I pull numbers out of the air too, sometimes. :shifty:

What does "actual test model" actually mean with regard to fusion propulsion, since we cannot even build a breakeven fusion powerplant?

Since a gasdynamic fusion engine would pretty much look like that on this craft:

I can't imagine it would be all that light.

If we divide 200 gigawatts by 600 kg, we get a specific power of over 333 000 kW/kg. If we calculate Daedalus' first stage thrust power to be roughly 39 terawatts, and we use the mass of the first stage as the engine mass (the engine only takes up a part of the mass, I know, I know), then we get a specific power of roughly 23 650 kW/kg. Which is comparable to the gasdynamic fusion figures, so maybe they are not absurd.

But whether those numbers could be reached in reality probably depends on whether the mass of the magnets and the cooling system can be crammed into that mass figure (unless the radiators aren't included, for whatever reason).

But: The very first page of this document that you link to states a specific power figure of 10 kW/kg, which is in standing with the various other numbers I have seen for more near-future concepts. The problem is that such a figure is far too low for meaningful interstellar travel. At that rate, a 200 gigawatt drive would mass 20 000 tons, a 2 terawatt drive 200 000 tons, and a 20 terawatt drive 2 000 000 tons. Entirely impractical.

Yeah, the Gasdynamic Mirror Fusion system... But that's not the MAX, though. We're sort of assuming fusion tech. is a lot farther along.

As for the actual test model, there are pictures here, here, here. I've just discovered those are just Gasdynamic mirrors, and not fusion engines, though... :shifty:.

So, I guess the 10 kw/kg figure is projected, then, and not experimental result?
I guess we'll either have to assume fusion tech. is further along or use a Daedalus-type engine. Really, though, the shuttles were sort of depending on the MCF fusion engine, so I might stubbornly stick with the first option, this is interstellar travel and colonization, after all...

An engine running for roughly a century? Project Daedalus only accelerated for roughly four years!

One can easily imagine such an engine breaking down over such a timescale, regardless of type...

The vibrations on Daedalus never tore the ship apart, or at least the designers didn't think they would.

If you have to add dampeners, they don't have to be shock absorbers, as with an Orion that actually does nuke itself over and over. They could for example be flexible struts, or springs, designed to dampen the force of vibration. Moving parts, yes, but not terribly unreliable.

Unless you're running them for a hundred years or more. :uhh:

Haha, flight time of a century, right... I slipped up there.

I think conclusion from earlier applies. Daedalus or handwavium of sorts. (I wouldn't really call MCF Max handwavium, though it is to some small degree.)



On the topic of our ISV propulsion system... I've hit a rather terrible issue.

See, all along I've been planning to use it for braking, and use a photon sail for the acceleration phase, so as to double the Delta-Vee...

Only to realize that the MegaWatts needed to propel a 50,000 ton spaceship (rough figure) to 18% c (another rough figure from 5 stages and 8,000,000 m/s Ve) using a photon sail was something with an e11 in Terawatts. :blink: . How the heck did James Cameron get away with that?
(This was all ball-parking math, btw. I don't actually expect the final numbers to be near this, it was just to get a rough idea of things.)

So I wonder how to calculate the requirements for an EM sail using beamed ions? :blink: How to even start...

And turn the women into babymaking machines. :dry:

You don't need to look at it that way... People could still have their own children, it's just families would have more than 2 children. And there are families that adopt, using another embryo would be something akin to that. Women doesn't even have to birth the baby, if biotech is advanced enough it could be born from an artificial womb. Though if you find that kind of sick, they can "adopt" an unborn child...

Remember that the nascent colony also needs a fair amount of manpower to get going, even with advanced technology.

That's very true. But a society can survive where every family has ~6 children.

Though this certainly does start to get into ethical issues...

Yeah, the problem with the tree-house thing is that it'd probably be impractical on this timescale. Maybe elsewhere though, somewhere, somehow.

You really want to try and culture proper polymers, rather than stuff like keratin (which has various limitations and impracticalities). Then again, stuff like chitin and cellulose are polymers. Cellulose only contains hydrogen, carbon and oxygen, which might be a bonus.

It's still viable even if your bacteria produce the compounds that polymers can be synthesised from. In fact, that'd likely be far easier to attempt than creating actual 'plastics' using bacteria.

But biological stuff like 'horn' or 'wood' are still interesting options. If you can grow and shape them, they'll be easier to deal with than plastics that have to be made via an artificial process using bacterial feedstock, etc.

I think that'd be much easier, making compounds that mix to form polymers instead of right-out breeding them. You could create 2 compounds in 2 facilities, when you go to construct something they're mixed in a fine spray, and bond much like 2-chemical glues. That way you can store them indefinitely as a liquid, then mix them together in a spray to solidify them. I think the strongest types of glues work this way, so it might even help with the strength of the material. Not to mention they dry very quickly. Might be able to build entire homes in just a few days.

 

[selden]

Only to realize that the MegaWatts needed to propel a 50,000 ton spaceship (rough figure) to 18% c (another rough figure from 5 stages and 8,000,000 m/s Ve) using a photon sail was something with an e11 in Terawatts. . How the heck did James Cameron get away with that?

Because he stole it from Forward. (And movies are about visuals, not reality. ) See [ame="http://en.wikipedia.org/wiki/Rocheworld"]Rocheworld - Wikipedia, the free encyclopedia[/ame] which claims Forward proposed 1500 Terawatts for a small exploratory vessel, and http://www.geoffreylandis.com/lightsail/lightsail89.html where Landis shows the math for Forward's scenarios.

 

[T.Neo]

Fish farming is still less efficient than vat meating. I'd just use different types of meat. Though it'd probably have a different texture.

Hmm, here we are discussing colonization of the first exoplanet, interstellar spacecraft propulsion and building a small civilization... And we're discussing eating fish? I like it.

I just thought that fish-farming would add variety and be a lower-tech addition to meat culturing.

To be honest It's been quiet awhile since I've read up on it. But from what I understand, it's disease-free, makes healthier plants, and is more dense per volume and mass, not to mention far more efficient in terms of water use. It's also been the target of lots of NASA studying, and has been carried aboard/conducted on the Shuttle and Mir, at least.
http://en.wikipedia.org/wiki/Aeropon..._of_aeroponics

That's interesting.

I found this image particularly intruiging:

So, I guess the 10 kw/kg figure is projected, then, and not experimental result?

I think 10 kW/kg is seen as the ideal figure for interplanetary fusion propulsion using technology being studied today.

On the topic of our ISV propulsion system... I've hit a rather terrible issue.

See, all along I've been planning to use it for braking, and use a photon sail for the acceleration phase, so as to double the Delta-Vee...

Only to realize that the MegaWatts needed to propel a 50,000 ton spaceship (rough figure) to 18% c (another rough figure from 5 stages and 8,000,000 m/s Ve) using a photon sail was something with an e11 in Terawatts. . How the heck did James Cameron get away with that?
(This was all ball-parking math, btw. I don't actually expect the final numbers to be near this, it was just to get a rough idea of things.)

So I wonder how to calculate the requirements for an EM sail using beamed ions? How to even start...

James Cameron got away with it because he used all the physics concepts, but none of their ramifications.

Here is a discussion of the financial and other problems of the Avatar ISV(s), with exceedingly precise figures for exceedingly imprecise situations (this is apparently before I heard of rounding off :facepalm).

I say, dump the lightsail. You need huge sails and huge lasers and stuff and frankly in the end of things I just think it's too much trouble. One option might be a particle beam sail, but would likely face other issues, some similar to a lightsail.

But I really would suggest researching a magnetic sail for deceleration; it could at least partially tackle the problem.

You don't need to look at it that way... People could still have their own children, it's just families would have more than 2 children. And there are families that adopt, using another embryo would be something akin to that. Women doesn't even have to birth the baby, if biotech is advanced enough it could be born from an artificial womb. Though if you find that kind of sick, they can "adopt" an unborn child...

Assuming you can create an artificial womb. There are a lot of things we don't just understand about pregnancy (or growing organs, for that matter). And it doesn't solve the issue of raising the children, either.

The thing is, even if you've got 1000 people, and you want 10 000 people, that's 10 embryos per woman. Even if you split it up over two generations or so, it's a big number (and the longer you wait the more issues you could potentially face with embryo degredation, etc.

The difference between this and adoption is that this is an institutionalised, structured attempt at babymaking. There are enough requirements on the colonists as it is, and social destabilisation due to extra pressures could be problematic.

That's very true. But a society can survive where every family has ~6 children.

Well, yes. But a group of only 100 people, for example, might have trouble managing a technologically advanced society. Granted, there are a lot of small towns in the US and elsewhere, but these are not totally isolated and people and goods can come in from the outside.

I'd advocate a multiple ship colonisation strategy. If a ship can carry 1000 people in stasis, ten ships can carry 10 000 people. In addition, the first colonisation wave could carry the initial 'seed' infrastructure, with following ships being able to carry less cargo and more passengers- the landers, shuttles and autofactories will likely be the single heaviest part of the payload.

In addition, multiple flights can be staggered, both to ease the economy back home, and to allow the first colonists to prepare for their arrival.

But that might not fit in with the strategy you had in mind.

think that'd be much easier, making compounds that mix to form polymers instead of right-out breeding them. You could create 2 compounds in 2 facilities, when you go to construct something they're mixed in a fine spray, and bond much like 2-chemical glues. That way you can store them indefinitely as a liquid, then mix them together in a spray to solidify them. I think the strongest types of glues work this way, so it might even help with the strength of the material. Not to mention they dry very quickly. Might be able to build entire homes in just a few days.

I was thinking more along the lines of creating organic chemicals using bacteria and then polymerising them more-or-less the same way we do now. Something like a 2-part glue would be pretty interesting though... and likely pretty effective, too. Almost like a plastic "cement".

 

[martins]

It seems to me that the most efficient strategy for interstellar colonisation would be to send an assortment of microorganisms. They are less fragile than humans, not fussy about food and don't get bored easily. They are superbly adaptable and also good at terraforming. The only slight disadvantage is that unpacking the civilisation at the target location might take a good number of million years - but what's a million years amongst cosmologists.

 

[T.Neo]

Million years? Those must be some speedy organisms... you'll be lucky if they set up civilisation in a billion years. :shifty:

Alas, most microorganisms would probably face the same fate as a human if dropped off in most environments in space. Dessicated, frozen, exposed to radiation, poisoned, every number of the above. We actually do quite well; even other organisms known to survive in space can only withstand it by going dormant. Our means of survival are no less legitimate than the behaviour of a weaver bird or a hermit crab.

For interstellar civilisation I personally recommend terrapins; small, lightweight, ectothermic (and thus requiring low food intake for their mass), able to survive in an aquatic environment, and they even carry their own protection against low-velocity impacts.

With the revolutionary use of terrapins, civilisation could be developed in mere hundreds of millions of years. :lol: