NASA Announces 1,284 New Exoplanets

[Broomstick]

Honestly I think I need to ask the obvious question. A solution for what? Life is not about overcoming difficulty for the sake of doing so. It's about a pursuit of happiness that involves overcoming difficulties that stand in the way of that pursuit. So what is the realistic motivation that could produce any of these things?

Pussy.

And no, I'm not entirely kidding.

Remember that women are choosy and men are in competition with each other. Women have a motivation to select the best mate for their offspring prior to investing 9 months of pregnancy followed by lactation and raising the rugrats for 20+ years. The factors that gain points in women's Darwinian gaze are 1) resources (wealth), 2) power (influence and ability to gather more resources), 3) ability to overcome problems (in the past that might have been cave bears, these days it's dealing with blocked plumbing, car troubles, armed intruders, making rockets go up without exploding and killing the occupants, etc.)

This is a reason men* are driven to accomplish things beyond the bare minimum for happiness - they want the happiness much sex brings, and that requires being "worthy" of the women. Men who explore over the hill marking the tribe's territory risk much, but might acquire new territory for the tribe and thus enjoy the attentions of women seeking a father for their children. This is part of what makes explorers and soldiers sexy.

So, arguably, the urge to go to space is a knock-on from human sexual selection.

Added to that, these days some people are genuinely concerned for the long-term survival of the species. Additionally, the human species clearly has some sort of drive to expand and, having filled up the planet (more or less) the only place to get more space is... space.




* since human behavior isn't as gender-bound as some species anything that leads to men acquiring a trait means women will also get it, and vice versa. This is why we have ambitious women interested in "male" fields, and men who are stay-at-home dads and primary caregivers. Take sweeping, generalized statements in this post with this in mind.

[Broomstick]

Bone mass under normal conditions degrades at such as speed that without solving this problem people would struggle getting to mars anyway.

Incidentally, this problem is almost solved, or at least much closer to being solved than the problem of hauling stuff out of a planet's gravity well. See this:
[snip video for space]
Here's the paper he was looking at: http://onlinelibrary.wiley.com/doi/10.1 ... .1647/epdf

Summarize the damn things, will you? Because this is, from my viewpoint, a casual on-line discussion and I don't care to invest hours of time in research. Give me the highlights and I'll decide if I want to read the original research.

Really? What's the fuel source for the Earth's rotation? It seems to be pretty stable, having only slowed by 1 part in nearly 90,000,000 over the past century.

A planet is not an artificially constructed habitat in space. There's no way we're going to replicate the stability of a large planet's rotation in a relatively small space habitat.

Because...? I really don't understand here. Space is a near vacuum, and the habitats I'm talking about will mass in the tens of billions of tonnes. What's going to stop them spinning once started?

Think about this, will you?

In addition to needing to get to the LaGrange points in the first place, and spinning it up to speed the first time, there will need to be a mechanism for making fine adjustments. We might have reason to move them in the future as well – if we find out a large space rock is headed for that point, for example, which can certainly happen. How sensitive to mass balancing will these be? Get too much mass at one point things will get unpleasant, sort of like an out-of-balance washing machine tub but much worse. Get a hull breach the escaping atmosphere is going to act like a thruster, you might need a way to compensate for that, maybe you'll even need to stop the rotation until repairs are made if things are bad enough, I don't know, I'm not an engineer.

Space is a NEAR vacuum, it's not a perfect vacuum, and this being reality, shit happens.

A lot compared to what? How much concrete and steel do you need to protect humans from radiation on Mars? Effectively no magnetic field, no ozone layer, no thick atmosphere, means that Mars' surface is nearly as prone to cosmic rays as circumterran space.

The difference between Mars and outer space is that you can burrow into the Martian surface, dig down a hundred feet if you want/need to do, or utilize a natural cave system, or expand one. In space you have to construct all that covering. On a planet's surface you can burrow into a mountain and thus put a kilometer of rock over your head pretty quickly.

Excavating an underground complex is a huge expenditure of energy that must be generated, and since there's no fossil fuel reserve on Mars, you have to bring all that energy with you.

Did you blast past where I mentioned utilizing a natural cave complex? Even if Mars doesn't have water-formed caves (debatable – there is some evidence of water flow on Mars but since it's a very different environment let's not assume there are water-carved caves there) there will almost certainly be lava-tubes because Mars has some very impressive volcanoes. If you're mining resources (arguably one of the reasons for bothering with a planet) just repurpose the played-out mines (we even do this on Earth).

Use solar power to manufacture rocket fuel from the Martian atmosphere – there's already work being done on that – and use tools powered by that fuel for excavating.

Yet more rocket ships from Earth. Then growing food underground is a huge expenditure of energy, ongoing. Load up the rockets, Sally, the people on Mars need to eat.

Space habitats have near-unlimited energy from solar arrays absorbing constant sunlight, and can grow food in near-ideal conditions year-round.

Who the hell said “grow food underground”? I said live underground, I didn't discuss the food issue. And yeah, I'm well aware of the “energy expenditure” of things like hydroponics because I've actually done those. The big cost of that is the lighting, and guess what? Mars gets daylight. Grow at least some of the food on the planet surface (obviously, in green houses of some sort, and you want multiple, separated units to minimize loss from breached structures) and use solar to power what is needed. We've been doing solar power on Mars for years now, that's what's been powering all those rovers and shit.

Heart muscles and bones atrophy in freefall, yes, but again, there's no reason habs have to have freefall internally. Habitats designed to rotate to provide apparent gravity were designed in the late 1960s and early 1970s, and no real questions have been brought up about the practically or efficacy of the designs. I recommend (as I always do) reading The High Frontier, by Gerard K. O'Neill.

Have any of them ever been built?

I'm pretty sure that you'd know if a 20 kilometer-long space habitat was orbiting in L4 or L5.

There is this device known as a “rhetorical question”. That was an example.

As far as your book assignments go, see below.

How well are people going to deal with the coriolis forces inherent in an artificial, rotating space habitat? I'd feel a lot more secure about promoting that solution if we had any real-world experience of it at all. Maybe we should build a few, see how they work out, see how compatible they are with people. So far, though, not one has been built that I'm aware of.

There have been lots and lots of research on how humans deal with coriolis force on the levels we're talking about. O'Neill discusses them, at length, in the book he wrote on the topic. Maybe, if you're curious about space habitats and the practical problems thereof, you could try picking up the book and reading it instead of asking me to explain it to you.

Since most of us have this thing called “a life” involving things like “working for a living” no, most of us do not appreciate you assigning us reading. Again – hit the relevant points and then cite your reference. Or didn't you understand what you read? You can't summarize it in 25 or 50 words or less?

Yes, I'm curious about space habitats but, sorry to break it to you, on a personal level making enough money to pay the rent and put food on the table takes precedence. I have time to read maybe 2 books a month. Give me a reason to prioritize your recommendations over all the other topics I'm interested in.

There have been studies done on coriolis force and centrifugal forces' effects on the human body. Many of those findings are summed up in the book I already mentioned, which should be required reading before entering this debate. These issues have already been brought up and debated, literally before everyone in this conversation save perhaps Broomstick were born. Before you try to poke holes and nitpick, maybe read the fuckin' books?

Again – we have limited time. MAYBE you could summarize things? Point to chapters and page numbers? Any indication from these experiments the minimum size needed for these habitats? Mechanical stress on the structure? Assuming you've read these books yourself you should be able to summarize something. Between raising kids, taking care of family members, working for a living, and so forth many of us have limited time however much we enjoy these discussions, have some consideration for us. Also limited resources – I have a microscopic book budget and while my local library is accommodating at finding books for me it can take up to three weeks at times which considerably slows down the conversation. Yeah, the books you mentioned sound fascinating but I can't go out an acquire them this morning so, meanwhile, give us the benefit of your research.

[Purple]

Honestly I think I need to ask the obvious question. A solution for what? Life is not about overcoming difficulty for the sake of doing so. It's about a pursuit of happiness that involves overcoming difficulties that stand in the way of that pursuit. So what is the realistic motivation that could produce any of these things?

Pussy.

And no, I'm not entirely kidding.

Remember that women are choosy and men are in competition with each other. Women have a motivation to select the best mate for their offspring prior to investing 9 months of pregnancy followed by lactation and raising the rugrats for 20+ years. The factors that gain points in women's Darwinian gaze are 1) resources (wealth), 2) power (influence and ability to gather more resources), 3) ability to overcome problems (in the past that might have been cave bears, these days it's dealing with blocked plumbing, car troubles, armed intruders, making rockets go up without exploding and killing the occupants, etc.)

This is a reason men* are driven to accomplish things beyond the bare minimum for happiness - they want the happiness much sex brings, and that requires being "worthy" of the women. Men who explore over the hill marking the tribe's territory risk much, but might acquire new territory for the tribe and thus enjoy the attentions of women seeking a father for their children. This is part of what makes explorers and soldiers sexy.

So, arguably, the urge to go to space is a knock-on from human sexual selection.

Added to that, these days some people are genuinely concerned for the long-term survival of the species. Additionally, the human species clearly has some sort of drive to expand and, having filled up the planet (more or less) the only place to get more space is... space.




* since human behavior isn't as gender-bound as some species anything that leads to men acquiring a trait means women will also get it, and vice versa. This is why we have ambitious women interested in "male" fields, and men who are stay-at-home dads and primary caregivers. Take sweeping, generalized statements in this post with this in mind.

That makes an oddly large amount of sense.

[jwl]

Bone mass under normal conditions degrades at such as speed that without solving this problem people would struggle getting to mars anyway.

Incidentally, this problem is almost solved, or at least much closer to being solved than the problem of hauling stuff out of a planet's gravity well. See this:
[snip video for space]
Here's the paper he was looking at: http://onlinelibrary.wiley.com/doi/10.1 ... .1647/epdf

Summarize the damn things, will you? Because this is, from my viewpoint, a casual on-line discussion and I don't care to invest hours of time in research. Give me the highlights and I'll decide if I want to read the original research.

Okay, basically they've got a new exercise machine, ARED, which works in keeping up bone density in space. It manages to keep the same or slightly increase overall bone density, but there's still some problems, like how the bone density in particular areas goes down even if the overall bone density stays the same. At some point in the future, I would expect these problems to get smoothed out too. Basically, click on the paper, scroll down to fig 4. It compares the results of previous missions to that of ones using ARED.

[Terralthra]

A planet is not an artificially constructed habitat in space. There's no way we're going to replicate the stability of a large planet's rotation in a relatively small space habitat.

Because...? I really don't understand here. Space is a near vacuum, and the habitats I'm talking about will mass in the tens of billions of tonnes. What's going to stop them spinning once started?

Think about this, will you?

In addition to needing to get to the LaGrange points in the first place, and spinning it up to speed the first time, there will need to be a mechanism for making fine adjustments. We might have reason to move them in the future as well – if we find out a large space rock is headed for that point, for example, which can certainly happen. How sensitive to mass balancing will these be? Get too much mass at one point things will get unpleasant, sort of like an out-of-balance washing machine tub but much worse. Get a hull breach the escaping atmosphere is going to act like a thruster, you might need a way to compensate for that, maybe you'll even need to stop the rotation until repairs are made if things are bad enough, I don't know, I'm not an engineer.

Space is a NEAR vacuum, it's not a perfect vacuum, and this being reality, shit happens.

O'Neill Island IIIs, the habitats in question, come in pairs which counter-rotate. Each thus has internal centrifugal gravity, while having a net rotational inertia which allows them to precess to always point at the sun, and use each other's rotation as a reaction wheel to make minor adjustments. Escaping atmosphere from a hull breach would be roughly akin to lowering one window a crack while driving on the highway. Yes, it will have an effect, but a minor one that is easily adjusted against. If the breach is so bad that the air escaping creates a large enough impulse to be of a worry, the habitat has probably got bigger problems.

The difference between Mars and outer space is that you can burrow into the Martian surface, dig down a hundred feet if you want/need to do, or utilize a natural cave system, or expand one. In space you have to construct all that covering. On a planet's surface you can burrow into a mountain and thus put a kilometer of rock over your head pretty quickly.

Excavating an underground complex is a huge expenditure of energy that must be generated, and since there's no fossil fuel reserve on Mars, you have to bring all that energy with you.

Did you blast past where I mentioned utilizing a natural cave complex? Even if Mars doesn't have water-formed caves (debatable – there is some evidence of water flow on Mars but since it's a very different environment let's not assume there are water-carved caves there) there will almost certainly be lava-tubes because Mars has some very impressive volcanoes. If you're mining resources (arguably one of the reasons for bothering with a planet) just repurpose the played-out mines (we even do this on Earth).

Use solar power to manufacture rocket fuel from the Martian atmosphere – there's already work being done on that – and use tools powered by that fuel for excavating.

Yet more rocket ships from Earth. Then growing food underground is a huge expenditure of energy, ongoing. Load up the rockets, Sally, the people on Mars need to eat.

Space habitats have near-unlimited energy from solar arrays absorbing constant sunlight, and can grow food in near-ideal conditions year-round.

Who the hell said “grow food underground”? I said live underground, I didn't discuss the food issue. And yeah, I'm well aware of the “energy expenditure” of things like hydroponics because I've actually done those. The big cost of that is the lighting, and guess what? Mars gets daylight. Grow at least some of the food on the planet surface (obviously, in green houses of some sort, and you want multiple, separated units to minimize loss from breached structures) and use solar to power what is needed. We've been doing solar power on Mars for years now, that's what's been powering all those rovers and shit.

Curiosity is powered by an RTG, not solar power. Spirit and Opportunity use solar power to generate a grand total of 140 watts per day, which allows them to operate at a blazing fast speed of 0.1 miles per hour while running their 20 MHz CPU. Since you know all about the energy expenditure of hydroponics, you'd know that the energy expenditure required is massive. Solar power on Mars is roughly 1/10th as efficient as Earth, generating 10 or so watts per square meter, compared to 140-160 W/m^2 on Earth. Generating rocket fuel from it will be even less efficient.

Growing food on the surface means they'll suffer the same radiation problems as humans would on the surface, oh, and they'll also probably die because they aren't getting enough sunlight. I guess you could use big focusing lenses for greenhouse roofs, but then you'll have to have 10x the farmland per food calorie grown. And add "clean dust off the acres and acres of glass while wearing a spacesuit" to your daily chores. Man, living on Mars is looking worse and worse.

How well are people going to deal with the coriolis forces inherent in an artificial, rotating space habitat? I'd feel a lot more secure about promoting that solution if we had any real-world experience of it at all. Maybe we should build a few, see how they work out, see how compatible they are with people. So far, though, not one has been built that I'm aware of.

There have been lots and lots of research on how humans deal with coriolis force on the levels we're talking about. O'Neill discusses them, at length, in the book he wrote on the topic. Maybe, if you're curious about space habitats and the practical problems thereof, you could try picking up the book and reading it instead of asking me to explain it to you.

Since most of us have this thing called “a life” involving things like “working for a living” no, most of us do not appreciate you assigning us reading. Again – hit the relevant points and then cite your reference. Or didn't you understand what you read? You can't summarize it in 25 or 50 words or less?

Yes, I'm curious about space habitats but, sorry to break it to you, on a personal level making enough money to pay the rent and put food on the table takes precedence. I have time to read maybe 2 books a month. Give me a reason to prioritize your recommendations over all the other topics I'm interested in.

Yes, I, too, have a job. I'm sorry your job doesn't offer you the leisure time to read, but that is not my fault. The summary is "Space habitats are cheaper than planetary surfaces, can be built in a much larger volume, house more people, offer better quality of life, and also massively improve life for planetary residents nearby by offering incredibly cheap power." It's more or less what I've already said.

There have been studies done on coriolis force and centrifugal forces' effects on the human body. Many of those findings are summed up in the book I already mentioned, which should be required reading before entering this debate. These issues have already been brought up and debated, literally before everyone in this conversation save perhaps Broomstick were born. Before you try to poke holes and nitpick, maybe read the fuckin' books?

Again – we have limited time. MAYBE you could summarize things? Point to chapters and page numbers? Any indication from these experiments the minimum size needed for these habitats? Mechanical stress on the structure? Assuming you've read these books yourself you should be able to summarize something. Between raising kids, taking care of family members, working for a living, and so forth many of us have limited time however much we enjoy these discussions, have some consideration for us. Also limited resources – I have a microscopic book budget and while my local library is accommodating at finding books for me it can take up to three weeks at times which considerably slows down the conversation. Yeah, the books you mentioned sound fascinating but I can't go out an acquire them this morning so, meanwhile, give us the benefit of your research.

Research on coriolis and centrifugal forces' effects indicates that about the fastest that humans can acclimate to in a short amount of time is 1 or so RPM, with some people able to acclimate to 2 or 3, but we can't design a habitat we intend to be for everyone for a plurality. Thus, in order to generate an effective apparent gravity without making people dizzy, the habitats have to be big. O'Neill's habitats range from 1 to 5 miles in diameter, allowing for a rotation between .9 (for the 1 mile ones) and .4 RPM (for the 5 mile ones) to generate an apparent .5-.8g. 1/2 g has been indicated (though not confirmed) as a lower bound necessary to maintain bone and muscle mass long-term, and accordingly, the smaller habitats (which have lower apparent gravity from a given rotational velocity) are "bootstrap" designs intended to serve as stepping stones on the way to the full-size, 20 km long x 8 km diameter cylinders.

[Simon_Jester]

Why would sunpower on Mars be an order of magnitude weaker than on Earth? The sunlight's only about, oh, (1.6^-2)... call it 40% as strong, but what else is going on there?

[Lord Revan]

I dunno if that was accounted but Mars has massive (as in practically planetwide) sandstorms fairly frequently.

[Terralthra]

Why would sunpower on Mars be an order of magnitude weaker than on Earth? The sunlight's only about, oh, (1.6^-2)... call it 40% as strong, but what else is going on there?

I'm quoting someone else's numbers, but it mentions non-tracking thin-film solar panel arrays, which are lighter-weight and cheaper, but less efficient than the photovoltaic c-Si cells used here. Presumably the reason to bring thin-film cells along is for durability and reduction of mass that you have to move by rocket from one planet to another, at the expense of overall energy generation. That, plus less intense sunlight plus dust storms plus not tracking the sun over the day adds up.

[Broomstick]

Okay, basically they've got a new exercise machine, ARED, which works in keeping up bone density in space. It manages to keep the same or slightly increase overall bone density, but there's still some problems, like how the bone density in particular areas goes down even if the overall bone density stays the same. At some point in the future, I would expect these problems to get smoothed out too. Basically, click on the paper, scroll down to fig 4. It compares the results of previous missions to that of ones using ARED.

Worst case, it looks like it at least dramatically slows down bone loss. A certain amount of bone density loss is, in fact, normal past the early 20's even under 1g.

I'd still have concerns about development - it's critical to achieve maximum possible bone density prior to physical maturity in humans. Even if we had viable spinning cylinders for adults at .5g that may not be sufficient for developing humans.

Curiosity is powered by an RTG, not solar power. Spirit and Opportunity use solar power to generate a grand total of 140 watts per day, which allows them to operate at a blazing fast speed of 0.1 miles per hour while running their 20 MHz CPU. Since you know all about the energy expenditure of hydroponics, you'd know that the energy expenditure required is massive. Solar power on Mars is roughly 1/10th as efficient as Earth, generating 10 or so watts per square meter, compared to 140-160 W/m^2 on Earth. Generating rocket fuel from it will be even less efficient.

It's not "is it more or less efficient than producing X on Earth" but rather "Is it more or less efficient than shipping X from Earth".

At present, Mars has a very low population and a lot of area - even if you have to use 10 times the solar panels you can still use solar power. There's no insurmountable reason you couldn't combine solar with RTG's or small nuclear power plants.

Growing food on the surface means they'll suffer the same radiation problems as humans would on the surface, oh, and they'll also probably die because they aren't getting enough sunlight.

One of the reasons we avoid radiation is because we want to live decades - food crops that will only live months before being harvested have less time to build up damage. We might want to maintain seed stock underground in artificial grow lights to avoid mutations but this is not such an issue for crops intended for consumption.

Also, no reason you can't supplement natural sunlight with artificial - I have to do that myself with hydroponics from November through February even here on Earth due to short winter days. Utilize Martian sunlight as much as you can, then fill in the gaps.

Man, living on Mars is looking worse and worse.

No one claimed it would be easy!

Yes, I, too, have a job. I'm sorry your job doesn't offer you the leisure time to read, but that is not my fault. The summary is "Space habitats are cheaper than planetary surfaces, can be built in a much larger volume, house more people, offer better quality of life, and also massively improve life for planetary residents nearby by offering incredibly cheap power." It's more or less what I've already said.

And yet, you'd have to grow food entirely with artificial power in space habitats, and they'd still be exposed to radiation... From a food production standpoint it's not that much different. A space habitat as far out as Mars would suffer from the same issues with diminishing solar power.

Research on coriolis and centrifugal forces' effects indicates that about the fastest that humans can acclimate to in a short amount of time is 1 or so RPM, with some people able to acclimate to 2 or 3, but we can't design a habitat we intend to be for everyone for a plurality. Thus, in order to generate an effective apparent gravity without making people dizzy, the habitats have to be big. O'Neill's habitats range from 1 to 5 miles in diameter, allowing for a rotation between .9 (for the 1 mile ones) and .4 RPM (for the 5 mile ones) to generate an apparent .5-.8g. 1/2 g has been indicated (though not confirmed) as a lower bound necessary to maintain bone and muscle mass long-term, and accordingly, the smaller habitats (which have lower apparent gravity from a given rotational velocity) are "bootstrap" designs intended to serve as stepping stones on the way to the full-size, 20 km long x 8 km diameter cylinders.

I still wonder if .5 g is sufficient for developing humans - there is, as far as I know, zero information on the effects of microgravity on growing human beings. That might mean children and their caretakers have to live on the biggest habitats with the highest g's until the kids are fully mature.

What sort of research has been done on construction materials? On a planetary surface building structures is a mature technology and a lot of the strength concerns involve compressive strength. In a spinning habitat you'd have to worry about tensile strength. About the only place on Earth that's a worry is in things like suspension bridges so I assume there is already some science and tech out there, but I'm not aware what, if any, different concerns there would be for such construction in space.

[Broomstick]

That, plus less intense sunlight plus dust storms plus not tracking the sun over the day adds up.

Having sun-tracking in a moving vehicle does present problems, but I fail to see why sun-tracking couldn't be incorporated in stationary panels, particularly when humans are nearby to service them when needed.

[Terralthra]

Curiosity is powered by an RTG, not solar power. Spirit and Opportunity use solar power to generate a grand total of 140 watts per day, which allows them to operate at a blazing fast speed of 0.1 miles per hour while running their 20 MHz CPU. Since you know all about the energy expenditure of hydroponics, you'd know that the energy expenditure required is massive. Solar power on Mars is roughly 1/10th as efficient as Earth, generating 10 or so watts per square meter, compared to 140-160 W/m^2 on Earth. Generating rocket fuel from it will be even less efficient.

It's not "is it more or less efficient than producing X on Earth" but rather "Is it more or less efficient than shipping X from Earth".

No, it's "is it more or less efficient than just doing it at the L5 LaGrange point?" The question of "Is it more efficient to produce X on Mars or ship it to Mars from Earth" presumes that it's a good idea to colonize Mars at all, compared to other options. Even if it were a good idea, the end goal of colonizing other objects in space is to relieve overpopulation pressure. Mars is a huge amount of work for shitty living conditions for far fewer people than Earth, and even once you do that, what's next? Colonize Venus? Colonize Jupiter's moons? With space habitats, the answer is "build more", which has the advantage of simplicity and extensibility. There are lots of NEO and floating rocks to melt down and make into habitats, just floating around.

At present, Mars has a very low population and a lot of area - even if you have to use 10 times the solar panels you can still use solar power. There's no insurmountable reason you couldn't combine solar with RTG's or small nuclear power plants.

Just the pressure vessel of a small nuclear power plant would mass as much as about 1/3 of the mass of everything we've sent into space combined, and it pretty much has to be sent in one piece. There isn't a rocket built that can lift 2,000 tonnes to Mars. The biggest rocket ever built was a Saturn V, and it could manage just about 50 tonnes to Luna. Not to mention the centrifuges and enrichment facilities. Man, the sheer idea of using a nuclear reactor as part of initial colonization plans for Mars is....mindboggling. The manufacturing facilities in which one might cast a pressure vessel are even bigger. On the plus side, a space habitat at L5 would make an excellent zero-G foundry in which to cast such a pressure vessel from asteroid materials and zip it off wherever you wanted.

Growing food on the surface means they'll suffer the same radiation problems as humans would on the surface, oh, and they'll also probably die because they aren't getting enough sunlight.

One of the reasons we avoid radiation is because we want to live decades - food crops that will only live months before being harvested have less time to build up damage. We might want to maintain seed stock underground in artificial grow lights to avoid mutations but this is not such an issue for crops intended for consumption.

Also, no reason you can't supplement natural sunlight with artificial - I have to do that myself with hydroponics from November through February even here on Earth due to short winter days. Utilize Martian sunlight as much as you can, then fill in the gaps.

The gap is year-round, though. There's no season on Mars in which there's enough sunlight to grow Earth plants that have worthwhile food value. Multiply all the food you want to grow by that 1/10th the power per area ratio of solar cells...

Man, living on Mars is looking worse and worse.

No one claimed it would be easy!

I'm not even talking about the difficulty of it, it just looks like an unpleasant life. Wake up in a cave, put on a space suit, dust off the solar panels and greenhouses for hours, then go inside the greenhouses and tend all the plants for hours (remember that if you want to do it by machine, you have to have even more solar panels to dust off in order to power the machine...), then go back into your cave to sleep after checking your dosimeter. Not a life I'd want.

Yes, I, too, have a job. I'm sorry your job doesn't offer you the leisure time to read, but that is not my fault. The summary is "Space habitats are cheaper than planetary surfaces, can be built in a much larger volume, house more people, offer better quality of life, and also massively improve life for planetary residents nearby by offering incredibly cheap power." It's more or less what I've already said.

And yet, you'd have to grow food entirely with artificial power in space habitats, and they'd still be exposed to radiation... From a food production standpoint it's not that much different. A space habitat as far out as Mars would suffer from the same issues with diminishing solar power.

Grow food by artificial power...? What? You put them in a greenhouse protected by a UV-glass filter and point them at the sun, shading them as necessary if the plants require night in order to grow. And since most plants don't need a day/night cycle, and need different conditions than humans for optimal growth anyway, you put them into separate sub-habs orbiting off the main hab, with their own climate control. Plentiful solar power allows machinery to tend them. And you don't need to put the habs out near Mars, but if you did, you could make the sun-reflecting mirrors larger and parabolic to effectively concentrate sunlight much more easily than you can on a planetary surface. In space, volume is a trivial concern.

Research on coriolis and centrifugal forces' effects indicates that about the fastest that humans can acclimate to in a short amount of time is 1 or so RPM, with some people able to acclimate to 2 or 3, but we can't design a habitat we intend to be for everyone for a plurality. Thus, in order to generate an effective apparent gravity without making people dizzy, the habitats have to be big. O'Neill's habitats range from 1 to 5 miles in diameter, allowing for a rotation between .9 (for the 1 mile ones) and .4 RPM (for the 5 mile ones) to generate an apparent .5-.8g. 1/2 g has been indicated (though not confirmed) as a lower bound necessary to maintain bone and muscle mass long-term, and accordingly, the smaller habitats (which have lower apparent gravity from a given rotational velocity) are "bootstrap" designs intended to serve as stepping stones on the way to the full-size, 20 km long x 8 km diameter cylinders.

I still wonder if .5 g is sufficient for developing humans - there is, as far as I know, zero information on the effects of microgravity on growing human beings. That might mean children and their caretakers have to live on the biggest habitats with the highest g's until the kids are fully mature.

If .5g isn't enough for developing humans, you just torpedoed Mars colonization. Gravity on Mars is 0.38g.

What sort of research has been done on construction materials? On a planetary surface building structures is a mature technology and a lot of the strength concerns involve compressive strength. In a spinning habitat you'd have to worry about tensile strength. About the only place on Earth that's a worry is in things like suspension bridges so I assume there is already some science and tech out there, but I'm not aware what, if any, different concerns there would be for such construction in space.

Rebar has plenty of strength in all directions to build structures of these sizes. The windows would be glass panels reinforced by steel and aluminum, which have way more than enough strength.

That, plus less intense sunlight plus dust storms plus not tracking the sun over the day adds up.

Having sun-tracking in a moving vehicle does present problems, but I fail to see why sun-tracking couldn't be incorporated in stationary panels, particularly when humans are nearby to service them when needed.

My guess is mechanical complexity and mass. Everything you send to Mars costs you a lot of money per kg, making efficiency per kg the priority, not efficiency overall.

[Broomstick]

It's not "is it more or less efficient than producing X on Earth" but rather "Is it more or less efficient than shipping X from Earth".

No, it's "is it more or less efficient than just doing it at the L5 LaGrange point?" The question of "Is it more efficient to produce X on Mars or ship it to Mars from Earth" presumes that it's a good idea to colonize Mars at all, compared to other options. Even if it were a good idea, the end goal of colonizing other objects in space is to relieve overpopulation pressure. Mars is a huge amount of work for shitty living conditions for far fewer people than Earth, and even once you do that, what's next? Colonize Venus? Colonize Jupiter's moons? With space habitats, the answer is "build more", which has the advantage of simplicity and extensibility. There are lots of NEO and floating rocks to melt down and make into habitats, just floating around.

YOU have come up with the notion that space colonization is to relieve population pressure, that is not seen as a universal goal. Some people favor the "lifeboat" goal, which doesn't require relocating massive numbers of people.

You also need more than just rocks. The notion of refining rocket fuel on Mars (as well as extracting oxygen for breathing, and various other volatiles) is that even if the atmosphere of Mars in very thin there is a still a lot of it. On space station you have to import gasses and liquids where on Mars you can extract them from the local environment.

Also - we're not going to colonize Venus. Jovian moons are a problem due to radiation, which locally is pretty intense. Mars and Earth's Moon are potential rocks for inhabitation.

Just the pressure vessel of a small nuclear power plant would mass as much as about 1/3 of the mass of everything we've sent into space combined, and it pretty much has to be sent in one piece. There isn't a rocket built that can lift 2,000 tonnes to Mars. The biggest rocket ever built was a Saturn V, and it could manage just about 50 tonnes to Luna. Not to mention the centrifuges and enrichment facilities. Man, the sheer idea of using a nuclear reactor as part of initial colonization plans for Mars is....mindboggling. The manufacturing facilities in which one might cast a pressure vessel are even bigger. On the plus side, a space habitat at L5 would make an excellent zero-G foundry in which to cast such a pressure vessel from asteroid materials and zip it off wherever you wanted.

How big are the ones that power nuclear submarines? Your point about weight is a good one, but what are the lower mass/power limits of nuclear power?

The gap is year-round, though. There's no season on Mars in which there's enough sunlight to grow Earth plants that have worthwhile food value. Multiply all the food you want to grow by that 1/10th the power per area ratio of solar cells...

And... what's your point? Growing food requires a certain amount of area.

I'm not even talking about the difficulty of it, it just looks like an unpleasant life. Wake up in a cave, put on a space suit, dust off the solar panels and greenhouses for hours, then go inside the greenhouses and tend all the plants for hours (remember that if you want to do it by machine, you have to have even more solar panels to dust off in order to power the machine...), then go back into your cave to sleep after checking your dosimeter. Not a life I'd want.

First - why do you assume all the dusting has to be done by people? Or even every day? If you have sun-tracking not only will that increase your power output, you can use the mechanism to sharply tilt panels to help with cleaning.

Second - just how much tending do think plants need?

My most primitive hydroponics set-up had no mechanical pumps. Human muscle power lifted jugs of growth solution above the plants for 10 minutes to flood the substrate, then lowered the jugs below the substrate and let gravity drain the excess out. Twice per day. Use of pulleys and other forms of leverage could make this more efficient, but still rely on muscle power. Labor intensive, yes, but I question that this would be the whole of anyone's day.

My most high tech set-up utilized a simple pump, basically like a sump-pump. Again, twice a day flood. Run pumps in sequence so instead of two high-intensity power peaks you have a more consistent use throughout the day/night cycle. I automated mine with some simple timers and only had to check in once a week when the thing was set up. For a larger scale, actual "farm", you'd want units to be running in sequential cycles - set up one group one week, another the next week, and so on. In addition to avoiding labor peaks this would also result in a more consistent, less episodic food production.

I haven't run any sort of calculations, but such a set up might be feasible for a Mars or a space colony.

Grow food by artificial power...? What? You put them in a greenhouse protected by a UV-glass filter and point them at the sun, shading them as necessary if the plants require night in order to grow. And since most plants don't need a day/night cycle, and need different conditions than humans for optimal growth anyway, you put them into separate sub-habs orbiting off the main hab, with their own climate control. Plentiful solar power allows machinery to tend them. And you don't need to put the habs out near Mars, but if you did, you could make the sun-reflecting mirrors larger and parabolic to effectively concentrate sunlight much more easily than you can on a planetary surface. In space, volume is a trivial concern.

You're going to need more than light. You need some way to recycle water through the system. You'll need to cycle air through the system. You'll need to either recycle or add nutrients to the system. In fluid-based hydroponics sanitation becomes a major concern - either a fungus outbreak or an algal bloom can kill your set up, I speak from experience on that.

If .5g isn't enough for developing humans, you just torpedoed Mars colonization. Gravity on Mars is 0.38g.

You are correct. It still remains that we don't know. It may be that .5 g (or whatever) induces sufficient bone growth for that gravity or less, which, if you are never subjected to greater than Mars gravity is OK. A problem if such a person wants to go to Earth, they might have to be very, very careful in order to minimize the risk of fracture.

What sort of research has been done on construction materials? On a planetary surface building structures is a mature technology and a lot of the strength concerns involve compressive strength. In a spinning habitat you'd have to worry about tensile strength. About the only place on Earth that's a worry is in things like suspension bridges so I assume there is already some science and tech out there, but I'm not aware what, if any, different concerns there would be for such construction in space.

Rebar has plenty of strength in all directions to build structures of these sizes. The windows would be glass panels reinforced by steel and aluminum, which have way more than enough strength.

Once you get an space-refinery up and running, and ore from asteroids, that will probably work but getting the initial set up is more problematic.

[Terralthra]

It's not "is it more or less efficient than producing X on Earth" but rather "Is it more or less efficient than shipping X from Earth".

No, it's "is it more or less efficient than just doing it at the L5 LaGrange point?" The question of "Is it more efficient to produce X on Mars or ship it to Mars from Earth" presumes that it's a good idea to colonize Mars at all, compared to other options. Even if it were a good idea, the end goal of colonizing other objects in space is to relieve overpopulation pressure. Mars is a huge amount of work for shitty living conditions for far fewer people than Earth, and even once you do that, what's next? Colonize Venus? Colonize Jupiter's moons? With space habitats, the answer is "build more", which has the advantage of simplicity and extensibility. There are lots of NEO and floating rocks to melt down and make into habitats, just floating around.

YOU have come up with the notion that space colonization is to relieve population pressure, that is not seen as a universal goal. Some people favor the "lifeboat" goal, which doesn't require relocating massive numbers of people.

I didn't come up with it, but I think anyone who doesn't think of relieving population pressure is incredibly short-sighted. Many of the problems facing us here on Earth are related to the number of people we're trying to house on one orbiting habitat, with all the limits on volume and energy inherent therein.

You also need more than just rocks. The notion of refining rocket fuel on Mars (as well as extracting oxygen for breathing, and various other volatiles) is that even if the atmosphere of Mars in very thin there is a still a lot of it. On space station you have to import gasses and liquids where on Mars you can extract them from the local environment.

Proposals for extracting breathable air and so on from Martian environments mostly focus on electrolyzing water, which is plentiful in space. Ice is everywhere.

Also - we're not going to colonize Venus. Jovian moons are a problem due to radiation, which locally is pretty intense. Mars and Earth's Moon are potential rocks for inhabitation.

That was pretty much my point. Venus and Jovian moons are completely unrealistic.

Just the pressure vessel of a small nuclear power plant would mass as much as about 1/3 of the mass of everything we've sent into space combined, and it pretty much has to be sent in one piece. There isn't a rocket built that can lift 2,000 tonnes to Mars. The biggest rocket ever built was a Saturn V, and it could manage just about 50 tonnes to Luna. Not to mention the centrifuges and enrichment facilities. Man, the sheer idea of using a nuclear reactor as part of initial colonization plans for Mars is....mindboggling. The manufacturing facilities in which one might cast a pressure vessel are even bigger. On the plus side, a space habitat at L5 would make an excellent zero-G foundry in which to cast such a pressure vessel from asteroid materials and zip it off wherever you wanted.

How big are the ones that power nuclear submarines? Your point about weight is a good one, but what are the lower mass/power limits of nuclear power?

Information on the reactors at the heart of a nuclear-powered submarine is understandably scarce. The previous generation of nuclear-powered attack submarines used an S8G reactor, and the reactor compartment massed 2750 tons. That's the whole compartment, though, not the integral reactor pressure vessel. Without classified access, I doubt I'm going to find detailed specs on that. Back in the day, there was a ship named the Sturgis whose midsection was replaced with a small PWR to provide power for the Panama Canal Zone. The containment vessel for the reactor and cooling loops was 350 tons, so I'm guessing that's about the smallest you could get back in the 60s, but most reactors from the 60s aren't considered especially safe today.

Bechtel, which develops a lot of nuclear power plants, is currently trying to get approval for a so-called "small modular" reactor called mPower, which is presumably about the smallest you'd want to build a commercial reactor while being efficient about it with a suitably long design life. It weighs 630 (Imperial) tons dry. Still impossibly large to ship interplanetarily.

The gap is year-round, though. There's no season on Mars in which there's enough sunlight to grow Earth plants that have worthwhile food value. Multiply all the food you want to grow by that 1/10th the power per area ratio of solar cells...

And... what's your point? Growing food requires a certain amount of area.

My point is that it requires a massive amount of area? I mean, I thought that was obvious. Growing food on Mars is going to be incredibly land-intensive, which in some senses defeats the purpose of going, since it'll be incredibly less efficient on a "required acreage per human" sense than Earth. Lots of science to accomplish, sure, but as far as colonies go, awful. It'd be like colonizing....I don't even know, colonizing the Nunavut or Kamchatka, only even worse. There may be strategic or scientific reasons to do so, but you wouldn't mark them as good habitable real estate.

I'm not even talking about the difficulty of it, it just looks like an unpleasant life. Wake up in a cave, put on a space suit, dust off the solar panels and greenhouses for hours, then go inside the greenhouses and tend all the plants for hours (remember that if you want to do it by machine, you have to have even more solar panels to dust off in order to power the machine...), then go back into your cave to sleep after checking your dosimeter. Not a life I'd want.

First - why do you assume all the dusting has to be done by people? Or even every day? If you have sun-tracking not only will that increase your power output, you can use the mechanism to sharply tilt panels to help with cleaning.

I don't assume that, it simply makes sense. Are you going to have one of those 0.1 mph rovers dust it? Dusting it with a machine is More Energy, and the whole point here is that energy on Mars' surface is expensive. You'd have to tilt them well over vertical to be sure that accumulated sand fell off, and even then, you're still going to have to sweep manually to get dust off. It's going to cling electrostatically because of how dry the Martian atmosphere is.

Second - just how much tending do think plants need?

My most primitive hydroponics set-up had no mechanical pumps. Human muscle power lifted jugs of growth solution above the plants for 10 minutes to flood the substrate, then lowered the jugs below the substrate and let gravity drain the excess out. Twice per day. Use of pulleys and other forms of leverage could make this more efficient, but still rely on muscle power. Labor intensive, yes, but I question that this would be the whole of anyone's day.

Did your hydroponics garden fulfill all of your caloric needs for an extended period of time? If it didn't, estimate the fraction it did fulfill, then multiply the amount of work you had to do by the reciprocal of that fraction to get the working day of a Martian farmer, after adding in time to clear off the solar panels and greenhouse roof.

Grow food by artificial power...? What? You put them in a greenhouse protected by a UV-glass filter and point them at the sun, shading them as necessary if the plants require night in order to grow. And since most plants don't need a day/night cycle, and need different conditions than humans for optimal growth anyway, you put them into separate sub-habs orbiting off the main hab, with their own climate control. Plentiful solar power allows machinery to tend them. And you don't need to put the habs out near Mars, but if you did, you could make the sun-reflecting mirrors larger and parabolic to effectively concentrate sunlight much more easily than you can on a planetary surface. In space, volume is a trivial concern.

You're going to need more than light. You need some way to recycle water through the system. You'll need to cycle air through the system. You'll need to either recycle or add nutrients to the system. In fluid-based hydroponics sanitation becomes a major concern - either a fungus outbreak or an algal bloom can kill your set up, I speak from experience on that.

Algal blooms are specific to hydroponics, but cycling air and water and nutrients through the system can all be done by human-supervised machines. These machines aren't an option on Mars because they'd be prohibitively expensive to run, energy-wise. I suppose if you had someone who really wanted to do manual farming, there's no reason to stop them.

It's also worth noting that travel time to and from the L5 Earth/Moon system is about the same as travel time to the moon - a few days. Travel time to Mars is way longer, and dependent on launch windows (there'd be launch windows to L5 daily, and non-optimal windows at all times that don't significantly increase time that much). If something goes wrong on a space habitat, help is not that far away. If something goes wrong on Mars....good luck!

What sort of research has been done on construction materials? On a planetary surface building structures is a mature technology and a lot of the strength concerns involve compressive strength. In a spinning habitat you'd have to worry about tensile strength. About the only place on Earth that's a worry is in things like suspension bridges so I assume there is already some science and tech out there, but I'm not aware what, if any, different concerns there would be for such construction in space.

Rebar has plenty of strength in all directions to build structures of these sizes. The windows would be glass panels reinforced by steel and aluminum, which have way more than enough strength.

Once you get an space-refinery up and running, and ore from asteroids, that will probably work but getting the initial set up is more problematic.

Thus the bootstrapping series of intermediate habitats O'Neill proposed. First a mining base (non-colony) on Luna to mine ores for a foundry at L4/L5, launched via coilgun (effective, with no atmosphere against the lower gravity on the Moon), then capture asteroids and comets near Earth to build a Bernal sphere (Island I), a Stanford torus (alternative design), which can build a larger sphere, which can serve as the housing for the work of building the full-size habitat.

Interest in space habitation cratered when the space program did, largely because it was never really fueled by a desire for exploration, but out of nationalism and cold-war era military-industrial spending. When the US won the space race (to Luna) and the Cold War wound down, so did the drive to go ever further, and with decreased launch frequency, economies of scale on launch costs never kicked in enough to make a lunar mining colony fit into the reduced NASA budget. Without the stepping stone, launch costs make any form of extraterran colonization extremely unlikely.

[Terralthra]

To add on to the nuclear question, there were many early prototype reactors like the SL-1 or ML-1, which produced a few MW of power in a compact reactor vessel of about 12-20 tonnes, but it was...not a particularly safe design, for a number of reasons, including the small size making it more vulnerable to criticality incidents than a larger reactor. It could be transported by rocket, but I'm not sure Martian colonists would welcome such a design, which had to be hand-loaded, was inadequately shielded (on purpose!), and was found to corrode so fast it would have to be replaced entirely within a decade of service (not good when sending massive expensive things to another planet).

[Broomstick]

YOU have come up with the notion that space colonization is to relieve population pressure, that is not seen as a universal goal. Some people favor the "lifeboat" goal, which doesn't require relocating massive numbers of people.

I didn't come up with it, but I think anyone who doesn't think of relieving population pressure is incredibly short-sighted. Many of the problems facing us here on Earth are related to the number of people we're trying to house on one orbiting habitat, with all the limits on volume and energy inherent therein.

Again, it depends on your end goal - if it's population relief that requires transporting lots of people, which is expensive, much more so than raw materials that don't require life support. If the primary goal is the survival of the species then you just transport a minimum number to set up a viable long-term colony and relying on breeding up numbers. Maybe you include additional genetic material to reduce inbreeding. Of course, the second option might mean allowing a lot of humanity to die. I'm not real keen on that, personally.

You also need more than just rocks. The notion of refining rocket fuel on Mars (as well as extracting oxygen for breathing, and various other volatiles) is that even if the atmosphere of Mars in very thin there is a still a lot of it. On space station you have to import gasses and liquids where on Mars you can extract them from the local environment.

Proposals for extracting breathable air and so on from Martian environments mostly focus on electrolyzing water, which is plentiful in space. Ice is everywhere.

Including Mars! (Not so much Venus... )

The gap is year-round, though. There's no season on Mars in which there's enough sunlight to grow Earth plants that have worthwhile food value. Multiply all the food you want to grow by that 1/10th the power per area ratio of solar cells...

And... what's your point? Growing food requires a certain amount of area.

My point is that it requires a massive amount of area? I mean, I thought that was obvious. Growing food on Mars is going to be incredibly land-intensive, which in some senses defeats the purpose of going, since it'll be incredibly less efficient on a "required acreage per human" sense than Earth. Lots of science to accomplish, sure, but as far as colonies go, awful. It'd be like colonizing....I don't even know, colonizing the Nunavut or Kamchatka, only even worse.

Nunavut and Kamchatka have long been inhabited by humans. There is even limited agriculture there but to be honest a major difference is that in summer arctic regions on Earth receive abundant sunlight which, as you note, is an issue on Mars at any time of year.

Colonizing Antarctica is a better analogy in some limited ways, a place where agriculture outside is impossible any time of year. Antarctic bases do, typically, contain some hydroponics but no one has built anything extensive enough to support even one small base.

Anyone trying to grow food on Mars is going to have to supplement the sunlight, and most likely that would be led lightning at an optimized wave length for photosynthesis rather than full-spectrum light.

There may be strategic or scientific reasons to do so, but you wouldn't mark them as good habitable real estate.

On the other hand, given the transport costs and other limitations of Earth-Mars shipping making such a base as self-reliant as possible is a wise idea. Unfortunatley, there are several obstacles to growing food on Mars:
1) lack of air
2) lack of warmth
3) lack of water
4) unsuitable soil chemistry
5) lack of sunlight

You're going to need an atmosphere concentrator of some sort to deal with the first as well as some sort of pressurized container to hold a suitable pressure, an airtight greenhouse. Fortunately, a greenhouse will also help with the heat problem though you'll still need a supplemental heater. Water will either need to be found on Mars (and will require chemical extraction) or brought with you. The soil chemistry is a problem - so far as know there is nothing like what we'd consider organic matter in Martian "soil", and way too much of some things like iron oxide. Results of actual tests on actual Martian soil with the Viking Lander have occasionally been described as "fizzy". Suffice to say, whatever Martian soil is, it ain't Earthly dirt. Unfortunately, the plants that do best in low light conditions are also the ones that tend to be best at soaking up heavy metals, which might render them toxic for humans. Provided you can obtain sufficient water and recycle it with some efficiency some sort of hydroponics or airponics is going to be the way to go, at least initially. The upside is that such set ups, provided they get sufficient light, take up less space allowing for smaller greenhouses... except for the issue of providing light on Mars. There's apparently been some work with concentrating sunlight via mirrors and transporting it via fiberoptics to where it's wanted. Not sure how practical that would be. Definitely, if you're using artificial light, even as a supplement, you'd want to optimize the wavelengths for plant growth.

Is growing food on Mars going to be easy? Nope. But, again, given the distances and time involved in transporting anything to Mars it might be worth the effort.

Did your hydroponics garden fulfill all of your caloric needs for an extended period of time? If it didn't, estimate the fraction it did fulfill, then multiply the amount of work you had to do by the reciprocal of that fraction to get the working day of a Martian farmer, after adding in time to clear off the solar panels and greenhouse roof.

We were getting about a pound or two (kilo) of food a week out of 3m x 4m room, and we only utilized part of the room, basically, the 1/3 just in front of the windows. Once set up about an hour a week of maintenance. A reset took more time, of course. Haven't extrapolated that out, but any set-up going to Mars is going to be way more efficient than my cobbled-together set-up.


There's a soilless set up on the ISS producing lettuce and radishes, which is a testbed for any sort of off-Earth food growing. We know it can be done because we've done it, the devil is in the details

I suppose if you had someone who really wanted to do manual farming, there's no reason to stop them.

There are psychological benefits to being around green, growing plants as well.

It's possible that the combination of carbon dioxide to oxygen conversion, psychological benefits of being near growing plants as well as the consumption of fresh food, and even limited agriculture as a stop-gap against an interruption in supply lines might make farming on Mars cost-effective in context. Completely self-sufficient? Probably not for a long time, but just as you can boot strap from smaller to larger space habitats you might be able to boot-strap Martian agriculture over the long term.

It's also worth noting that travel time to and from the L5 Earth/Moon system is about the same as travel time to the moon - a few days. Travel time to Mars is way longer, and dependent on launch windows (there'd be launch windows to L5 daily, and non-optimal windows at all times that don't significantly increase time that much). If something goes wrong on a space habitat, help is not that far away. If something goes wrong on Mars....good luck!

At this point, if something goes wrong even in orbit help in time to do anything is unlikely. For a long time the only rescue in space is going to be self-rescue, which is one reason that figuring out a way to grow food on Mars is so attractive.

Interest in space habitation cratered when the space program did, largely because it was never really fueled by a desire for exploration, but out of nationalism and cold-war era military-industrial spending. When the US won the space race (to Luna) and the Cold War wound down, so did the drive to go ever further, and with decreased launch frequency, economies of scale on launch costs never kicked in enough to make a lunar mining colony fit into the reduced NASA budget. Without the stepping stone, launch costs make any form of extraterran colonization extremely unlikely.

The other reason the space race wound down is lack of a something worth the cost of going there. Remember, initially Europe's interest in the New World was spices or gold - in other words, valuable stuff they hoped to find there. We got to the Moon and didn't immediately find "gold", so no industrial interests to help start space industry.

[Guardsman Bass]

Overpopulation pressure isn't particularly useful as a push factor on space colonization. Even ignoring the effects of the Demographic Transition in bringing population growth rates down, it's going to be expensive to send people off-world for the foreseeable future, and the places where population growth rates are the highest (well above the replacement rate) also tend to be the poorest places on Earth. Nobody is going to pay to send the surplus offspring of subsaharan Africa into space colonies.

[K. A. Pital]

The only way to space is a better civilization that can focus on long-term planning.

This is also why I support the Asians. They seem to have a very long planning span in comparison to Western nations. Their companies live longer, their states plan for longer.

It is pointless to hope for the market to provide us with space colonies as there is no immediate or even mid-term gain.

[The Romulan Republic]

The only way to space is a better civilization that can focus on long-term planning.

This is also why I support the Asians. They seem to have a very long planning span in comparison to Western nations. Their companies live longer, their states plan for longer.

It is pointless to hope for the market to provide us with space colonies as there is no immediate or even mid-term gain.

You are making an extremely broad generalization about people's attitudes and abilities on the basis of race. I'd go so far as to call it racist stereotyping.

[Terralthra]

And... what's your point? Growing food requires a certain amount of area.

My point is that it requires a massive amount of area? I mean, I thought that was obvious. Growing food on Mars is going to be incredibly land-intensive, which in some senses defeats the purpose of going, since it'll be incredibly less efficient on a "required acreage per human" sense than Earth. Lots of science to accomplish, sure, but as far as colonies go, awful. It'd be like colonizing....I don't even know, colonizing the Nunavut or Kamchatka, only even worse.

Nunavut and Kamchatka have long been inhabited by humans. There is even limited agriculture there but to be honest a major difference is that in summer arctic regions on Earth receive abundant sunlight which, as you note, is an issue on Mars at any time of year.

Colonizing Antarctica is a better analogy in some limited ways, a place where agriculture outside is impossible any time of year. Antarctic bases do, typically, contain some hydroponics but no one has built anything extensive enough to support even one small base.

That is why I said like Nunavut or Kamchatka but worse. Like, even Antarctica is better than Mars, because on Antarctica you can breathe outside, you know?

There may be strategic or scientific reasons to do so, but you wouldn't mark them as good habitable real estate.

On the other hand, given the transport costs and other limitations of Earth-Mars shipping making such a base as self-reliant as possible is a wise idea. Unfortunatley, there are several obstacles to growing food on Mars:
1) lack of air
2) lack of warmth
3) lack of water
4) unsuitable soil chemistry
5) lack of sunlight

You're going to need an atmosphere concentrator of some sort to deal with the first as well as some sort of pressurized container to hold a suitable pressure, an airtight greenhouse. Fortunately, a greenhouse will also help with the heat problem though you'll still need a supplemental heater. Water will either need to be found on Mars (and will require chemical extraction) or brought with you. The soil chemistry is a problem - so far as know there is nothing like what we'd consider organic matter in Martian "soil", and way too much of some things like iron oxide. Results of actual tests on actual Martian soil with the Viking Lander have occasionally been described as "fizzy". Suffice to say, whatever Martian soil is, it ain't Earthly dirt. Unfortunately, the plants that do best in low light conditions are also the ones that tend to be best at soaking up heavy metals, which might render them toxic for humans. Provided you can obtain sufficient water and recycle it with some efficiency some sort of hydroponics or airponics is going to be the way to go, at least initially. The upside is that such set ups, provided they get sufficient light, take up less space allowing for smaller greenhouses... except for the issue of providing light on Mars. There's apparently been some work with concentrating sunlight via mirrors and transporting it via fiberoptics to where it's wanted. Not sure how practical that would be. Definitely, if you're using artificial light, even as a supplement, you'd want to optimize the wavelengths for plant growth.

See, this is what I'm saying. Habitats at the Earth/Moon L4/L5 suffer from fewer of these problems, and have other benefits besides.

I suppose if you had someone who really wanted to do manual farming, there's no reason to stop them.

There are psychological benefits to being around green, growing plants as well.

It's possible that the combination of carbon dioxide to oxygen conversion, psychological benefits of being near growing plants as well as the consumption of fresh food, and even limited agriculture as a stop-gap against an interruption in supply lines might make farming on Mars cost-effective in context. Completely self-sufficient? Probably not for a long time, but just as you can boot strap from smaller to larger space habitats you might be able to boot-strap Martian agriculture over the long term.

The proposed interior of the habitat proper can have lots and lots of green plants around. Here's an artist's conception.

It's also worth noting that travel time to and from the L5 Earth/Moon system is about the same as travel time to the moon - a few days. Travel time to Mars is way longer, and dependent on launch windows (there'd be launch windows to L5 daily, and non-optimal windows at all times that don't significantly increase time that much). If something goes wrong on a space habitat, help is not that far away. If something goes wrong on Mars....good luck!

At this point, if something goes wrong even in orbit help in time to do anything is unlikely. For a long time the only rescue in space is going to be self-rescue, which is one reason that figuring out a way to grow food on Mars is so attractive.

Well, if something goes wrong on the ISS, it's a short time-line to help because even a small leak in atmosphere, for example, is huge given the low volume of the habitat overall. A hull breach (like, say, one of the panels of the three major window stripes) on an Island III is miniscule, comparatively.

[Broomstick]

Like, even Antarctica is better than Mars, because on Antarctica you can breathe outside, you know?

Well, sure - and on Mars there is an actual atmosphere even if it's very thin and you could theoretically have a machine that concentrates it to a desirable pressure and changes the gas mixture to something humans can breathe comfortably whereas in a space habitat you have to import all gases instead of simply gathering them from the local environment.

There may be strategic or scientific reasons to do so, but you wouldn't mark them as good habitable real estate.

On the other hand, given the transport costs and other limitations of Earth-Mars shipping making such a base as self-reliant as possible is a wise idea. Unfortunately, there are several obstacles to growing food on Mars:
1) lack of air
2) lack of warmth
3) lack of water
4) unsuitable soil chemistry
5) lack of sunlight

You're going to need an atmosphere concentrator of some sort to deal with the first as well as some sort of pressurized container to hold a suitable pressure, an airtight greenhouse. Fortunately, a greenhouse will also help with the heat problem though you'll still need a supplemental heater. Water will either need to be found on Mars (and will require chemical extraction) or brought with you. The soil chemistry is a problem - so far as know there is nothing like what we'd consider organic matter in Martian "soil", and way too much of some things like iron oxide. Results of actual tests on actual Martian soil with the Viking Lander have occasionally been described as "fizzy". Suffice to say, whatever Martian soil is, it ain't Earthly dirt. Unfortunately, the plants that do best in low light conditions are also the ones that tend to be best at soaking up heavy metals, which might render them toxic for humans. Provided you can obtain sufficient water and recycle it with some efficiency some sort of hydroponics or airponics is going to be the way to go, at least initially. The upside is that such set ups, provided they get sufficient light, take up less space allowing for smaller greenhouses... except for the issue of providing light on Mars. There's apparently been some work with concentrating sunlight via mirrors and transporting it via fiberoptics to where it's wanted. Not sure how practical that would be. Definitely, if you're using artificial light, even as a supplement, you'd want to optimize the wavelengths for plant growth.

See, this is what I'm saying. Habitats at the Earth/Moon L4/L5 suffer from fewer of these problems, and have other benefits besides.

Er... like what "fewer"? OK, they have more sunlight, but otherwise they lack soil, water, warmth, and air. So far as I can see the only advantage to your habitat is that it gets more sun. They also lack gravity which is bad for human health. You've having to import a lot of stuff to your L4/L5 points.

The proposed interior of the habitat proper can have lots and lots of green plants around. Here's an artist's conception.

Uh-huh.... all of which will need maintenance and tending. Some someone is going to be doing the scutwork regardless of whether they're in space or on Mars.

If you have a personal bias for space habitats that's totally OK, but the obstacles to making them long-term self-sufficient human habitations are daunting, just like setting up a Mars colony is daunting.

Well, if something goes wrong on the ISS, it's a short time-line to help because even a small leak in atmosphere, for example, is huge given the low volume of the habitat overall. A hull breach (like, say, one of the panels of the three major window stripes) on an Island III is miniscule, comparatively.

Actually, Mir had a hull puncture and depressurization and while it was certainly serious and classified as an emergency no one was injured by it, either. And the guys up there had to deal with it rather than rely on help from the ground.

The main difference is that if you run out of food at L5 you can probably do without until a supply ship is sent in a week or two. On Mars... not so much. But "running out of food" with modern preservation methods is way down on the list of likely problems. Running out of water, air, or power would be much more serious and in neither case is depending on outside help a viable strategy.

[jwl]

The only way to space is a better civilization that can focus on long-term planning.

This is also why I support the Asians. They seem to have a very long planning span in comparison to Western nations. Their companies live longer, their states plan for longer.

It is pointless to hope for the market to provide us with space colonies as there is no immediate or even mid-term gain.

In what sense do Asian companies live longer? Are there many asian companies which have lasted significantly longer than, say, Lloyds bank or Cadburys?

[K. A. Pital]

The only way to space is a better civilization that can focus on long-term planning. This is also why I support the Asians. They seem to have a very long planning span in comparison to Western nations. Their companies live longer, their states plan for longer. It is pointless to hope for the market to provide us with space colonies as there is no immediate or even mid-term gain.

You are making an extremely broad generalization about people's attitudes and abilities on the basis of race. I'd go so far as to call it racist stereotyping.

Hurhur, quick, accuse of racism to strenghten your point... which was what exactly, do remind? That I've made a common-sense observation?

Richard Foster, a lecturer at the Yale School of Management, has found that the average lifespan of an S&P company dropped from 67 years in the 1920s to 15 years today. Foster also found that on average an S&P company is now being replaced every two weeks, and estimates that 75 percent of the S&P 500 firms will be replaced by new firms by 2027.

http://www.theatlantic.com/business/arc ... ie/390249/

Though survival is important to firms, especially to the Japanese big businesses, there are few empirical studies on their longevity. This paper conducts the statistical analysis on the longevity of the Japanese big businesses using data on 1,273 listed firms in the first section of Tokyo Stock Exchange. The result indicates that the longevity of the Japanese big businesses may go beyond a century on average, and the longevity had increased gradually in the post-WWII period. These findings suggest that the Japanese big businesses are stable. This paper also explores the relationship between this stability and the Japanese corporate systems.

http://www.gbrc.jp/journal/abas/pdf/ABAS1-3-1.pdf

In what sense do Asian companies live longer? Are there many asian companies which have lasted significantly longer than, say, Lloyds bank or Cadburys?

In the absolute sense. See above. Lloyds Bank existed for 250 years, Cadbury for 191 years. That's formidable, but pretty much average for a Japanese company. The real dinosaurs there live beyond 300 years. Oldest companies exist for beyond 1000 years.

[Terralthra]

Like, even Antarctica is better than Mars, because on Antarctica you can breathe outside, you know?

Well, sure - and on Mars there is an actual atmosphere even if it's very thin and you could theoretically have a machine that concentrates it to a desirable pressure and changes the gas mixture to something humans can breathe comfortably whereas in a space habitat you have to import all gases instead of simply gathering them from the local environment.

Oxygen and nitrogen are found commonly on asteroids and comets, which can be "gathered from the local environment" too.

Er... like what "fewer"? OK, they have more sunlight, but otherwise they lack soil, water, warmth, and air. So far as I can see the only advantage to your habitat is that it gets more sun. They also lack gravity which is bad for human health. You've having to import a lot of stuff to your L4/L5 points.

Space habitats do not lack gravity. They have centrifugal gravity, which they generate by spinning. You can find more information on this if you scroll up and look at posts to which you previously replied. Space habitats have more gravity than Mars, which only has 0.38g. This has already been explained to you.

The proposed interior of the habitat proper can have lots and lots of green plants around. Here's an artist's conception.

Uh-huh.... all of which will need maintenance and tending. Some someone is going to be doing the scutwork regardless of whether they're in space or on Mars.

As previously mentioned, and replied to by you, the difference is that a space habitat can have plentiful solar electricity to power machinery to help or do the work for the humans, while on Mars solar power is an order of magnitude less efficient, meaning fewer machines to assist.

If you have a personal bias for space habitats that's totally OK, but the obstacles to making them long-term self-sufficient human habitations are daunting, just like setting up a Mars colony is daunting.

At no point have I claimed that there are not daunting obstacles. My claim all along has been that for a smaller or similar amount of infrastructure and work setting them up, space habitats offer a better quality of life, are more efficient at housing humans (which stands to reason, since that's what they're designed to do and Mars is not), and are more expandable.

Well, if something goes wrong on the ISS, it's a short time-line to help because even a small leak in atmosphere, for example, is huge given the low volume of the habitat overall. A hull breach (like, say, one of the panels of the three major window stripes) on an Island III is miniscule, comparatively.

Actually, Mir had a hull puncture and depressurization and while it was certainly serious and classified as an emergency no one was injured by it, either. And the guys up there had to deal with it rather than rely on help from the ground.

Well, by "deal with it", they meant "seal off that area and never use it again". Spektr had its emergency bulkhead closed and it was never repressurized before Mir was deorbited. I don't really count that as fixing the problem.

[Simon_Jester]

In the absolute sense. See above. Lloyds Bank existed for 250 years, Cadbury for 191 years. That's formidable, but pretty much average for a Japanese company. The real dinosaurs there live beyond 300 years. Oldest companies exist for beyond 1000 years.

To be fair, Japanese companies that trace their history back to before the Meiji Restoration are not necessarily the ones who are better at planning, just the ones who were better at ingratiating themselves with the Shogunate and with the Imperial government that replaced it. I'm not sure it's reasonable to bring those up as examples.

However, this is irrelevant to the core of your point, which is that Japanese companies are at present, on average, more stable than American companies. And possibly more so than European or British companies, I'm not sure from the evidence I've seen you post.

[biostem]

Would a space habitat need to keep a lot of fuel on hand for things like correcting its orbit or other maneuvers, or could they implement some system where they can collect and store electricity via solar panels, and use that to somehow produce thrust as needed?