Survival on Mars: Radiation & Temperature Challenges

[enorbet]

Nuclear things in space (and on earth) are even more frowned upon now.
Yes microprocessors follow Moore's law, but engines and power sources do not.

To speed up travel time in a relevant way, you have to get away from Hohmann orbits, and then you need a significantly more powerful propulsion system.

While I agree that public opinion is hysterical regarding nuclear power in general, I'd like to point out that considerable (and maybe just a teeny bit less hysterical) public outrage tried to prevent LHC from ever powering up due to worries over Black Holes. Obviously and thankfully, LHC went ahead.

Of course I am aware that Moore's Law doesn't apply to propulsion systems... directly. However indirectly it very much does IMHO and in some very important ways. First off, recalling that Apollo and especially the Shuttle were launched and used with very obsolete equipment due to the large gap in time between design and implementation, and further, applying that to the designs of all Nuclear Space Propulsion Systems (UK, Russian, as well as US) the best data I can find shows that the latest design dates were around 1966. While there may have been some later tweaking of design factors, it is my understanding that as great as the results were, they were severely hindered by infighting between nuclear physicists who had never flown, and chemical rocket engineers that had no nuclear experience and considerable prejudice.

NERVA was part of Project Rover in the US and was to take place in 3 phases. The final Specific Impulse of double that of chemical rocket engines was achieved with Phase 2, and Phase 3 was never completed that was to substantially increase that figure and these designs too were from ~1966, without modern computer modeling or microprocessor monitored/controlled control systems.

I know almost nothing of the limiting factors on how far that specific impulse could be improved but I am assuming if doubling could occur with that ancient technology, and the next 2x to 4x increase was deemed feasible with that technology (and they did meet or exceed every goal), that perhaps 6x NERVA XE (Phase 2, or 12x Phase 1) is within the realm of possibility. If this is so, then specific impulse could reach 10-12 times that of chemical systems. I think that can be called "significant".

I am further aware of the sharp increase that occurs since any velocity gained must also be shed but that is exactly why nuclear is worth considering. This also applies if the numbers look bad for increased velocity because they should still look great for payload. That we can use computer modeling before any physical testing is required/desired circumvents Public Opinion. Once we have real numbers, derived not in 1966 but in 2014, many obstacles may be reduced and some disappear altogether.

As a spinoff, even just more (and more modern) research into nuclear energy control systems certainly can't hurt. I think it is possible to consider this development in increments sufficiently palatable to Congress and/or venture capitalists that progress can be made. As it is we are rather standing still.

 

[enorbet]

@MattRob - As you might guess I am an enthusiast, a former Amateur Rocketeer and I don't mean Estes kits and the like but serious machined metal monsters, some as large as 4 feet tall and 2.0" engine diameter (maybe not so "monstrous" now but 3 feet was all engine, and hey, I was 13 at the time). So I too have been following SpaceX and Mars1 with great interest. I sincerely hope you, and they, are right and that milestones will continue that will convince the government and the public (and even a few foot-draggers in the scientific community) this is not only doable but terrifically exciting. The world could certainly use a common, peaceful, high-minded crusade to match the challenge JFK set for us all so many years ago. Science could certainly use the good PR.

 

[MattRob]

@MattRob - As you might guess I am an enthusiast, a former Amateur Rocketeer and I don't mean Estes kits and the like but serious machined metal monsters, some as large as 4 feet tall and 2.0" engine diameter (maybe not so "monstrous" now but 3 feet was all engine, and hey, I was 13 at the time). So I too have been following SpaceX and Mars1 with great interest. I sincerely hope you, and they, are right and that milestones will continue that will convince the government and the public (and even a few foot-draggers in the scientific community) this is not only doable but terrifically exciting. The world could certainly use a common, peaceful, high-minded crusade to match the challenge JFK set for us all so many years ago. Science could certainly use the good PR.

Heh, that's pretty darn impressive. Wish I could say I've worked on stuff like that, hah. The thing I love about private space exploration, though, is you don't need to convince the government to grant taxpayer money - no, instead you have customers that pay you directly. It's a much more natural model that's far more sustainable. Lewis and Clark or Apollo type expeditions do great on government money, but once its done its done and that's it. But put it in the private sector, and suddenly, not just a few exploration missions, but colonization starts to happen.

I was actually just writing a bit thinking that your estimates on increased efficiency are a bit optimistic, but looking this up again, although NERVA could never do it, I do see other Nuclear Thermal designs that could that were also covered in project Rover.
I used Wiki to start.
Gas Core article.
Citations from wiki:
http://web.archive.org/web/20080315125447/http://www.lascruces.com/~mrpbar/rocket.html
http://pdf.aiaa.org/preview/CDReadyMASM07_1064/PV2007_35.pdf

That's definitely some awesome technology, though tbh I don't imagine it being a more likely solution to be employed than VASIMR coupled with nuclear powerplants, and I certainly don't think it's necessary to go to Mars (could be very nice for grander explorative missions later on, though). It could help, definitely, but I think overall these private companies are making the right choice to just go and do it instead of waiting for these technologies to bear fruit.

Also, read up on Project Timberwind?

 

[enorbet]

@MattRob Thank you for those links. I learned quite a bit.

Gentlemen, my apologies. I was unaware that NASA was in fact already conducting computer modeling which has apparently been active at the Marshall Center for about a year. I don't yet find substantial results but it has just begun and the very real efficiency numbers should ultimately win out.

Presently I am most interested in how this can develop into improved space exploration but the major obstacle of winning over public opinion allowing us to explore nuclear energy of all types (thanks to safe computer modeling), may prove the most difficult hurdle but also the greatest long term boon to mankind.

 

[chasrob]

Unfortunately, the soil and dust of Mars has been found to also be rich in perchlorates, silicates, and gypsum, enough so to be toxic to humans.
The universe is out to kill us. :L

 

[QuantumPion]

The first is a major issue because the shortest route currently takes many months during which the travelers receive about 80% lifetime maximum radiation exposure. Providing the craft with a meter of so thickness of lead skin is an issue.

The second is made more critical if arriving with a large exposure; the subsequent exposure during the visit needs to be minimized.

The third, coming back, is the same issue as the trip there - exposure on the trip there plus exposure on the trip back exceeds lifetime max exposure by a large margin, no even counting the accumulation while there.

You don't need a meter of lead to shield the crew. You just need to surround the crew compartment with the water, oxygen, and fuel that you are bringing along anyway. I think radiation dose is among the less significant hurdles involved in planning a manned mission to mars.

 

[Drakkith]

Mars is about as lush for us, with our current technology, as the colonial Americas were for the early colonists' technology. More so, I'd say, actually, since we wouldn't have to worry about disease and the cold of winter in the ways that they had to. Or hostile natives, heh. The big difference in-between us and them is that they had a real strong incentive to go and colonize the Americas. Natural resources/colonialism, and religious freedom, as I understand it. Interesting to me it is, that it wasn't until hundreds of years after the first explorers sailed there that colonies - or even the motivations for those colonists to go - appeared.

This is absolutely, positively, 100% wrong. The colonization of the Americas doesn't even compare to the colonization of Mars except in the most vaguest of ways. Colonists certainly didn't need to rely on technology in the way we would on Mars. Just look at the significant technological differences between the various cultures of the Americas and between them and the European colonists. You have everything from people living in dug out dirt hovels with spears all the way up to people living in cabins with guns, intercontinental ships, and advanced metallurgy. Plus, the climate of the Americas is generally much more temperate than Europe, especially in the southern areas of North America where many of the early explorers landed.

 

[Chronos]

I am in the skeptic majority on a manned Mars mission by 2030. Getting there is doable, building habitat [underground, obviously] is doable, providing power is probably doable. Establishing a self sustaining ecosystem on Mars - not even remotely possible. Ferrying supplies to Mars is uneconomical and unreliable. Miss a food shipment; possibly survivable: miss a water shipment; risky: miss an 02 shipment; game over. Any optimism for a manned mission to Mars by 2030 is a pipe dream. It would be far more sensible to first build a moon base, then assemble and launch the mission from there. I fail to see the logic investing effort in a Mars mission instead of a moon base. A moon base could even become profitable in less time than we could realistically work out the kinks for a safe Mars mission.

 

[enorbet]

Other than boyhood dreams fueled by ScFi writers, I too see no compelling reason to leap to Mars when our Moon is vastly closer. While it isn't a direct analogy, just imagine if "The New World", instead of being 6,000 km was 600,000 km distant. That would be a daunting problem even today, let alone with sailing ships in the 16th-19th Centuries.

 

[mfb]

Other than boyhood dreams fueled by ScFi writers, I too see no compelling reason to leap to Mars when our Moon is vastly closer. While it isn't a direct analogy, just imagine if "The New World", instead of being 6,000 km was 600,000 km distant. That would be a daunting problem even today, let alone with sailing ships in the 16th-19th Centuries.

Compare the new world at a distance of 6000km with a small, uninhabited rock forming a small island at a distance of 60km. Sure you can explore the rock, but a whole new continent looks more interesting.

 

[enorbet]

Compare the new world at a distance of 6000km with a small, uninhabited rock forming a small island at a distance of 60km. Sure you can explore the rock, but a whole new continent looks more interesting.

Point well taken. However I submit that while we have logged in a not inconsiderable amount of space time we have most definitely not logged in much time on any other worlds, and we've only been to one. I don't know the exact amount of elapsed time that men spent actually on our moon, walking or driving around, exploring and collecting, but I doubt it is much more than a few days elapsed time. We dropped the ball before the game really had begun in earnest.

Besides the fact that the moon as an object for exploration has far more to offer in exploration than a "small, uninhabited island" on Earth (subject to at least very similar environmental changes within the window of what can exist on Earth as opposed to starting from the same mass in a largely molten state but evolving in entirely different ways) it just seems wise to crawl > walk > run in sequence and not risk too much, too soon.

I grant you that one major value of Mars is that with men on the surface the question of "did Mars ever host Life?" would likely be resolved much faster than with robotics, and that is a biggy, but I am not ruling out Mars exploration (we need to go!) just figuring on building some "sea legs" before we venture "so far out to sea".

 

[mfb]

Moon is certainly a relevant target, but I think Mars is much more interesting in the long run. Looking at the Chinese space program, a return to the moon could come within a reasonable time (maybe even before the last of the 12 Apollo astronauts to walk the moon dies), but I don't see the point in large moon bases now. Significantly cheaper transportation systems from Earth to LEO would change a lot.

6 missions from 1 day to 3 days, so in total about 10 days * 2 astronauts.

 

[MattRob]

For general consideration, I've found this paper while doing some reading on Gas Core Nuclear Rockets (GCNR). It has an absolutely fantastic section on "the n-word," though, that I feel is a must-read (n being for nuclear, of course, heh). And looking over more of it now, the whole thing is just rather fantastic about spaceflight and Mars colonization in general.

http://web.archive.org/web/20060821143407/http://www.lascruces.com/~mrpbar/Space Policy 02.pdf

(I should note, though, that I don't really agree with his assertion that chemical propulsion doesn't foot the bill. I think it's failed so far, but SpaceX and commercial space are really the ones that will prove its ability to put payloads in LEO economically)

This is absolutely, positively, 100% wrong. The colonization of the Americas doesn't even compare to the colonization of Mars except in the most vaguest of ways. Colonists certainly didn't need to rely on technology in the way we would on Mars. Just look at the significant technological differences between the various cultures of the Americas and between them and the European colonists. You have everything from people living in dug out dirt hovels with spears all the way up to people living in cabins with guns, intercontinental ships, and advanced metallurgy. Plus, the climate of the Americas is generally much more temperate than Europe, especially in the southern areas of North America where many of the early explorers landed.

Well, that's coming off a bit strong, heh.

Actually, they relied on technology quite a bit. It took large sailing ships to get there and a lot of specialized equipment they had to bring to build the colonies when they arrived. As you pointed out, they used guns, intercontinental ships and advanced metallurgy, not to mention a host of other equipment needed to build the colonies when there. Going to Mars, we'd have a substantial advantage of being able to transport our habitats there instead of having to build them there (granted, we may have to inflate and move in there, or pile soil against it).

True, there's a huge difference in-between a wooden sailing ship and a modern spacecraft . But at the same time, in a way they're both very similar: they're technology; technology built by, crewed by, and carrying humans. Colonizing the Americas was, oh, let's say a hundred times easier than colonizing Mars will be. They didn't need to synthesize their own air, or maintain a pressurized environment, and the extremes of temperatures we face and lengths we'd have to go to grow food and extract potable water are much greater. But while going to Mars may be a hundred times as difficult, our technological capabilities are a hundred times superior.

And, yes, early explorers landed in the southern areas of North America, but later colonists had to deal with some rather harsh seasonal conditions further north.

I have ancestors who were Mormon pioneers, crossing the great plains, and there's plenty a tale of hardship that pioneers faced on those plains. One particular group suffered tremendously from freezing weather and food shortages, and suffered many losses. Now, with our advanced technological capabilities, I can make a trip ten times as far, in hours instead of weeks or months, across far more hostile conditions and through far worse environments, and my worst complaint might be not enough room to stretch my legs or being made to empty my pockets and walk through a metal arch.

It's much harder, yes, but we're much more capable now and we're ready to accept the challenge, certainly far more ready than we were to go to the moon in 1957, when we had never even put anything into orbit.

I am in the skeptic majority on a manned Mars mission by 2030. Getting there is doable, building habitat [underground, obviously] is doable, providing power is probably doable. Establishing a self sustaining ecosystem on Mars - not even remotely possible. Ferrying supplies to Mars is uneconomical and unreliable. Miss a food shipment; possibly survivable: miss a water shipment; risky: miss an 02 shipment; game over. Any optimism for a manned mission to Mars by 2030 is a pipe dream. It would be far more sensible to first build a moon base, then assemble and launch the mission from there. I fail to see the logic investing effort in a Mars mission instead of a moon base. A moon base could even become profitable in less time than we could realistically work out the kinks for a safe Mars mission.

But that's the key - you don't need it to be self-sustaining. You only need it to be efficient enough that the loss rates are managable by extracting resources from the Martian environment.

Working the plasma hydrodynamics of a gas-core nuclear reactor is hard. Creating a fusion powerplant that breaks even is hard. Discovering the Higgs was hard.

Heck, designing a fully re-usable launch vehicle that is unprecedented in its safety, performance, uses new technologies and is 4x cheaper than anything currently existing? That is hard (That's SpaceX's Falcon 9), yet most of those goals have already been met, and progress is looking great on meeting the rest.

In fact, that's something NASA engineers have long called impossible.

Melting and filtering water that you can literally just dig out of the ground, though? Extracting nitrogen from the environment? Performing electralysis on that water to get hydrogen and oxygen? Then mixing some atmospheric Co2 with the hydrogen to get CH4 fuel in-situ? Growing an aeroponics garden? Compared to building the boosters to go to Mars, these problems are a piece of cake. I seriously don't see how any of those problems even come close to being show-stoppers.

A lot of new private aerospace companies aren't hiring experienced engineers - but are seeking out engineers fresh from college - because there's too much pessimism out there in the established field: They want engineers who "don't know what's impossible." We really need something like Mars colonization, I think, to quell a lot of that pessimistic thinking. At least SpaceX and Bigelow with orbital hotels should do that, as if Virgin Galactic's private spaceflight shouldn't have done that already.

But I think footage of people happily living and working on Mars could really give humanity a huge dose of inspiration and optimism that it needs.

Other than boyhood dreams fueled by ScFi writers, I too see no compelling reason to leap to Mars when our Moon is vastly closer. While it isn't a direct analogy, just imagine if "The New World", instead of being 6,000 km was 600,000 km distant. That would be a daunting problem even today, let alone with sailing ships in the 16th-19th Centuries.

I think the best analog I've seen is Greenland and the continental Americas. Simply put, although Greenland is closer, the Americas are far more hospitable. Mars has nitrogen, co2, an atmosphere that can stop micrometeorites, plentiful water ice for oxygen and everything you need to synthesize fuel+oxidizer in-situ readily available. The moon... not so much.

And yes, physically speaking, the ratio in-between the distance to Luna and Mars is much greater than for Greenland and the Americas, but in terms of Delta-vee costs, employing aerocapture, Mars is even closer (that is, the Mars/Luna delta-vee ratio is smaller than the America/Greenland distance ratio).

 

[mvdb]

How about quantum teleportation research... : http://www.cnet.com/news/scientists-make-quantum-leap-teleport-data-farther-than-ever-before/

 

[mvdb]

It seems to me that as research for quantum teleportation progresses, we might be able to teleport materials, machines, may be food to Mars.

 

[GTOM]

While i really found the quantum stuff interesting, i think it is a bit offtopic, and it is very highly speculative, that we could use it to teleport material.

Well i read about MOXIE (Mars Oxygen In-situ resource utilization Experiment) that meant to produce oxigen on Mars. I hope it will bring good results.
While i favor Mars because it has water and at least a thin atmosphere, but it also makes sense, that at first make a lunar colony, so we can have experience, confidence, maybe smaller launch costs.

 

[Dryson]

• How do you breath? Tranquility module - http://www.nasa.gov/centers/kennedy/stationpayloads/tranquility.html

• How do you drink? Tranquility module - http://www.nasa.gov/centers/kennedy/stationpayloads/tranquility.html

• How do you eat? See Food - http://en.wikipedia.org/wiki/International_Space_Station#Food

• How do you treat medical problems? See Medical - http://en.wikipedia.org/wiki/International_Space_Station#Medical

• How do you treat psychological problems? Astronauts would be sent on the mission who are extensively trained in how to deal with psychological problems that would arise. I would assume that NASA would establish a routine daily check of systems that rotated everyday where someone new would check an entire system to avoid the onset of monotonous routines that then would cause the astronauts mind to wander into deeper and deeper delusions to escape the monotony. Or an attached HEM C or D or similar type module would provide an area for the crew to gather communicate with family as well as social activities such as playing PlayStation or trying to paint a picture of the voyage.

 

[Chronos]

I applaud your optimism MattRob, but, realistically we have solved few of the very real problems of survival on Mars without counting on regular resupply missions, which would be expensive and risky from earth. It will take nearly a year to send a supply ship to mars, so system failures or malfunctions are very real and potentially deadly concerns. These are concerns in just getting to mars, much less supporting a colony once there. We can't be certain there is even enough extractable water on Mars to support a colony. The experience of first building a self sufficient colony on the moon would vastly improve the prospects of a successful Mars colony, not to mention reduce costs. At least on the moon, help is only days away.

 

[Drakkith]

MattRob, colonizing Mars and colonizing the Americas are so far removed from each other that I find

Actually, they relied on technology quite a bit. It took large sailing ships to get there and a lot of specialized equipment they had to bring to build the colonies when they arrived. As you pointed out, they used guns, intercontinental ships and advanced metallurgy, not to mention a host of other equipment needed to build the colonies when there. Going to Mars, we'd have a substantial advantage of being able to transport our habitats there instead of having to build them there (granted, we may have to inflate and move in there, or pile soil against it).

The key here is that the colonists didn't need that technology to simply survive. To flourish as well as they did, yes, but not to survive. A small group of people could have literally washed up on the shore with nothing but the clothes on their back and had at least some chance of surviving. Heck, groups of people walked from Siberia thousands of years ago and colonized both American continents with far less technology.

So you're previous claim, that Mars is about as lush for us as the Americas were for early colonists, simply makes no sense.

 

[mfb]

It seems to me that as research for quantum teleportation progresses, we might be able to teleport materials, machines, may be food to Mars.

No. Even if we neglect the problem how to scale teleportation up from a few objects to 1000000000000000000000000000000 atoms, you would still need the raw material on mars, and you would have to put the teleported atoms together on mars. In other words, you gain nothing.

Heck, designing a fully re-usable launch vehicle that is unprecedented in its safety, performance, uses new technologies and is 4x cheaper than anything currently existing? That is hard (That's SpaceX's Falcon 9), yet most of those goals have already been met, and progress is looking great on meeting the rest.

Falcon 9 is not re-usable. It did not have enough launches to evaluate its safety in practice. Performance is hard to compare. It does use new technologies (every new product does). The costs are similar to other commercial rockets.
Falcon 9-R is supposed to be partially re-usable (just the booster).

Working the plasma hydrodynamics of a gas-core nuclear reactor is hard. Creating a fusion powerplant that breaks even is hard. Discovering the Higgs was hard.

Apparently finding the Higgs was easier, it has been achieved with less money (compared to fusion) and earlier.

 

[Dryson]

3D Printing is being tested by NASA in an upcoming I.S.S. mission. The great thing about 3D printing is that it can used to create anything from replacement parts to vitamins and even food that all that is needed is a stored amount of printing material to print what ever is needed.

3D printing - parts http://www.makepartsfast.com/2012/08/4085/nasa-turns-to-3d-printing-for-parts-for-its-rover/
3D printing - vitamins http://www.3dprinterworld.com/article/3d-printed-vitamin-b2-implants
3D printing - food http://www.nasa.gov/directorates/spacetech/home/feature_3d_food_prt.htm

 

[mfb]

3D printing cannot create vitamins or any other chemical substances. It can use a vitamin-rich raw material to make vitamin-rich objects in new shapes. You still need the raw material. This saves material only if you do not know in advance which shape you need (because one out of xxxx different parts could fail).

 

[DHF]

As MFB stated, 3D printers can't create whole new objects, they just assemble things. in the Case of 3D food printers, what they are bringing to the table is variety. you could supply your expedition to Mars with tons of non perishable rations and it will keep them fed but it would be very monotonous after a while. the 3D printer simply let's them construct a variety of foods so they have more options but they would still need an equal amount of stored ration materiel. they can't simply pack a Wunderkind super-material that the printer can either make pizza or engine parts out of interchangeably. It is how the press would like you to think of them but that's not the case.

 

[Chronos]

I'm not aware of any examples of 3D printers that can manufacture oxygen or water.

 

[GTOM]

Ok, new arguments fits here, at first why i see Mars a fine place for colonization vs other proposals.

You have lots of materials in asteroids, on lightly gravitating moons and planetoids, in comets, and in Saturn's rings. And you have the whole of empty space in which to expand.

I admit the return to Earth part is harder, but in the movie, they didnt want to return.
But they might want to get to other destinations in space.

You can't expand to empty space, just to places with enough building material, traveling between asteroids (and properly spin up colonies) requires a good amount of delta-V even if one don't have to leave a gravity well.
Continue the journey to other destinations, well at this point we arent in such a hurry.

2. There are great plans for sure, at this point i will be happy if they can keep a single plant alive on Mars.
It is a good question, whether underground water could still exists, like we have wells on Earth?

3. I also think that building bases for constant living on Moon will be a very good practice and convincing that we can do that (while evacuate people if we fail), at least.

 

[Pete Cortez]

You can't expand to empty space, just to places with enough building material

Or you can move building material to empty space, which is precisely what you'll want to do if you want to assemble--say--O'Neill cylinders at Earth-Lunar libration.

Let's face it, you can't "just" expand into any place in the solar system. Everywhere off Earth is extremely hostile in comparison.

travelling between asteroids (and properly spin up colonies) requires a good amount of delta-V even if one don't have to leave a gravity well.

More often than not less than getting off Earth in the first place, and considerably so for several NEAs. And also considerably less than the delta-v budget needed to get to Mars' surface. And even considered more exotic, optimal paths to specific targets.

3. I also think that building bases for constant living on Moon will be a very good practice and convincing that we can do that (while evacuate people if we fail), at least.

The Moon's proximity to Earth is about her only saving grace, but it's a very big mark in her favor. Until we can shepherd comets and asteroids closer to Earth and/or stand up a reliable transportation network to NEAs and comets, the Moon is the most advantageous place to make gas and refine building materials within our reach. But I can definitely imagine a future where the Moon, once a booming nexus of early space settlement activity, ends up being littered with ghost towns as easier to access resources become available.

 

[GTOM]

NEA mining is quite reasonable, but building permanent, self sustaining settlements there is a different thing.
I don't deny that mining and trading with Earth are powerful factors, but living on planets is far better i think. If we can construct an artificial biosphere in space, i think we can solve landing on another planet also.
Many challenges are the same in the two case, however, on a planet, you won't run out of building material, people can see a horizont, a sky, leave the domes at least for a short time, transport between cities is easy (no need for rockets), you don't need to spin up everything, protection from radiation and micrometeors is easier. Probably in the future, leaving a planet will be also easier, in weaker gravity we could construct a space elevator.

 

[Pete Cortez]

NEA mining is quite reasonable, but building permanent, self sustaining settlements there is a different thing.

Building permanent, self-sustaining settlements anywhere off Earth is a different thing. I'd argue it's still easier to build them in freefall than while fighting surface gravity.

I don't deny that mining and trading with Earth are powerful factors, but living on planets is far better i think. If we can construct an artificial biosphere in space, i think we can solve landing on another planet also.

It's not a matter of finding solutions so much as picking optimal ones out of our current basket. I'd argue it's cheaper to hollow out a rock in freefall and fill it with water and atmosphere sourced from comets and the like than to set up a mining and transport operation for most of that material at Martian surface gravity. I also get the benefit of all sorts of raw material left over from primary construction just floating around outside waiting to be used.

Many challenges are the same in the two case, however, on a planet, you won't run out of building material

You won't run out of building material in space, either.

people can see a horizont, a sky...

I hope we're not making decisions to settle places based on whether or not there's a horizon. As for a sky, this doesn't work?

leave the domes at least for a short time

And this is different from a space habitat how? Not only could you leave the habitat, you get to enjoy freefall as well.

transport between cities is easy (no need for rockets)

Setting aside you can build multiple cities in a single asteroid, you can also connect multiple asteroids with cables. Or you can use tethers to fling material around. Or they simply might be close enough that you can get around in a reasonable amount of time on electric rocket propulsion. But most importantly, you'll be able to travel between destinations on very low energy paths, with delta-vs comparable to motor vehicle and air travel (within the same Lagrange neighborhood at least).

...you don't need to spin up everything

This is, to a first order approximation, a one time cost. And not necessarily a substantial one. In fact, you could conceivably use the extraction operation on an asteroid to provide spin by flinging byproduct into space. With good project and waste management, you can work it out so that all your heavy lifting work is done while rotation is close to zero.

protection from radiation and micrometeors is easier.

It's also easy by having a couple of meters of rock around you. Natural light can be reflected in through an opening on the end facing safely away from the sun.

Probably in the future, leaving a planet will be also easier, in weaker gravity we could construct a space elevator.

Remember, the same technologies you can apply to making it easier to lift off a planet can be used to make freefrall travel easier as well. A space elevator is a special case of a tether.

 

[Drakkith]

Building permanent, self-sustaining settlements anywhere off Earth is a different thing. I'd argue it's still easier to build them in freefall than while fighting surface gravity.

I don't think I agree. Both environments have different engineering requirements, and I don't think one is inherently easier than the other.

It's not a matter of finding solutions so much as picking optimal ones out of our current basket. I'd argue it's cheaper to hollow out a rock in freefall and fill it with water and atmosphere sourced from comets and the like than to set up a mining and transport operation for most of that material at Martian surface gravity. I also get the benefit of all sorts of raw material left over from primary construction just floating around outside waiting to be used.

I don't agree with this either. Comets have substantially different orbits than asteroids and I'd bet the fuel costs just getting to the comet and back would probably not make this worthwhile, and that's not even considering the cost of the operation to "mine" the comet.

And this is different from a space habitat how? Not only could you leave the habitat, you get to enjoy freefall as well.

Freefall is not something I'd consider to be enjoyable for most people. There's a reason why the zero-g training aircraft is nicknamed "vomit comet".

Setting aside you can build multiple cities in a single asteroid, you can also connect multiple asteroids with cables. Or you can use tethers to fling material around. Or they simply might be close enough that you can get around in a reasonable amount of time on electric rocket propulsion. But most importantly, you'll be able to travel between destinations on very low energy paths, with delta-vs comparable to motor vehicle and air travel (within the same Lagrange neighborhood at least).

You are not going to be able to connect multiple asteroids with cables. The average distance between asteroids is something like a few hundred thousand miles. Travel time between them would probably be a minimum of a few days, and that's with considerable fuel expended for acceleration and deceleration.

 

[Pete Cortez]

I don't think I agree. Both environments have different engineering requirements, and I don't think one is inherently easier than the other.

Energy-wise, there's a sharp distinction. Specifically where it concerns per pound, end-to-end transportation cost of materials. Even if we set aside the cost of dropping material and assume we build everything with material extracted from surface, you still have the energy expended overcoming friction. That concern is negligible in freefall transportation.

I don't agree with this either. Comets have substantially different orbits than asteroids and I'd bet the fuel costs just getting to the comet and back would probably not make this worthwhile, and that's not even considering the cost of the operation to "mine" the comet.

You'll want to capture them on close approach, and pick off the ones with low relative velocity. And assuming you don't want to use nukes to capture them, then pick a large enough one and start cracking hydrolox for propellant.

Freefall is not something I'd consider to be enjoyable for most people. There's a reason why the zero-g training aircraft is nicknamed "vomit comet".

There's a degree of acclimation, yes.

You are not going to be able to connect multiple asteroids with cables. The average distance between asteroids is something like a few hundred thousand miles. Travel time between them would probably be a minimum of a few days, and that's with considerable fuel expended for acceleration and deceleration.

I'm proposing connecting captured asteroids that have been parked in cislunar space. The average minimum distance is whatever traffic control says is safe. That's the beautiful thing about asteroids. They're mountains we can move.

 

[Drakkith]

Energy-wise, there's a sharp distinction. Specifically where it concerns per pound, end-to-end transportation cost of materials. Even if we set aside the cost of dropping material and assume we build everything with material extracted from surface, you still have the energy expended overcoming friction. That concern is negligible in freefall transportation.

Just because it may use less energy does not mean that it is easier. Working in zero-g and in a vacuum is much different than working on the surface of a planet, and comes with its own set of difficulties and engineering challenges.

You'll want to capture them on close approach, and pick off the ones with low relative velocity. And assuming you don't want to use nukes to capture them, then pick a large enough one and start cracking hydrolox for propellant.

I'm sorry but I feel like you're hand-waving the difficulties away.

There's a degree of acclimation, yes.

Which isn't always possible. Plus there's the fact that any environment is almost certainly going to be simulating gravity by rotating, so the acclimation may wear off. That being said, I can easily imagine some pretty creative "recreational facilities" being setup in a zero-g environment. Just look at the battle arena in Enders Game for an example. I don't think you can fully replace a planetary environment with a zero-g one, but I can imagine you can get pretty close and in some cases exceed what is possible in certain ways.

I'm proposing connecting captured asteroids that have been parked in cislunar space. The average minimum distance is whatever traffic control says is safe. That's the beautiful thing about asteroids. They're mountains we can move.

Ignoring all the costs and difficulties associated with moving these asteroids in the first place, I still don't agree that transportation is necessarily easier between asteroids than between cities on a planet. I will agree that in certain areas, perhaps like moving large quantities of material, it may be easier, but general transportation of people and goods, no. The reliability and simplicity of ground vehicles simply can't be beat. You don't need to spend years learning how to pilot a truck like you do a spacecraft . Besides, if anything goes wrong, you can just get out and push!

 

[Pete Cortez]

Just because it may use less energy does not mean that it is easier. Working in zero-g and in a vacuum is much different than working on the surface of a planet, and comes with its own set of difficulties and engineering challenges.

When it comes to the vacuum and Mars, we're talking about the difference 0 and 0.6 percent of Earth's mean sea level pressure. And working in space doesn't necessarily mean working in freefall conditions. If there's work that's best performed under acceleration, you spin it. But I imagine a good deal of work with very massive components would be actually easier to perform in freefall.

I'm sorry but I feel like you're hand-waving the difficulties away.

Not handwaving them away; any project off Earth is going to be considerably difficult compared to its terrestrial equivalent. I'm simply addressing the comparative difficulty of working in space vs working on an extra-terrestrial planet.

Which isn't always possible.

It's going to have to be. There's no way to transport people off this planet to other destinations without them spending some time in freefall.

Plus there's the fact that any environment is almost certainly going to be simulating gravity by rotating, so the acclimation may wear off.

It may, it may not. Symptoms at this transition point are not well known. Then again, symptoms we may encounter on an extraterrestrial planet aren't well known either.

That being said, I can easily imagine some pretty creative "recreational facilities" being setup in a zero-g environment. Just look at the battle arena in Enders Game for an example. I don't think you can fully replace a planetary environment with a zero-g one, but I can imagine you can get pretty close and in some cases exceed what is possible in certain ways.

I can imagine some pretty creative recreational activities in freefall, too. ;)

Ignoring all the costs and difficulties associated with moving these asteroids in the first place, I still don't agree that transportation is necessarily easier between asteroids than between cities on a planet.

Which is easier? Transporting over rough terrain? Paving highways? Or running cables?

I will agree that in certain areas, perhaps like moving large quantities of material, it may be easier, but general transportation of people and goods, no. The reliability and simplicity of ground vehicles simply can't be beat.

Ground transport isn't simple the vehicle. It's also roads.

You don't need to spend years learning how to pilot a truck like you do a spacecraft .

We spend years learning to pilot spacecraft because there are so few of them and they perform several, extremely different roles (launch, orbiter, reentry). And who says you even need a pilot for an inter-asteroid cable car?

Besides, if anything goes wrong, you can just get out and push!

That's probably not practical for more than a few miles, and even then most people would opt for a tow truck, hitch a ride or just walk. And it's not like you wouldn't be able to do the same in the interior of these space habitats. The question is for long distance travel--the realm that is also well served by ship, train and plane.

 

[Drakkith]

When it comes to the vacuum and Mars, we're talking about the difference 0 and 0.6 percent of Earth's mean sea level pressure. And working in space doesn't necessarily mean working in freefall conditions. If there's work that's best performed under acceleration, you spin it. But I imagine a good deal of work with very massive components would be actually easier to perform in freefall.

I agree that certain things are easier in freefall, but I don't agree that it's inherently better than non-freefall. And I thought we were talking about building a settlement, in which case you wouldn't be able to use acceleration to help you build things since there's no settlement there to spin.

Not handwaving them away; any project off Earth is going to be considerably difficult compared to its terrestrial equivalent. I'm simply addressing the comparative difficulty of working in space vs working on an extra-terrestrial planet.

No, you're skipping over the cost and difficulties of a huge portion of the project. Think about what you're saying. You want to start a mining operation on a comet and then take everything you mine to fill a hollowed out asteroid. If you want to use Mars as an example, I can find plenty of O2 and water on Mars without needing to ever get into a rocket, completely negating any need to ship either of those to the colony.

It's going to have to be. There's no way to transport people off this planet to other destinations without them spending some time in freefall.

I agree that there's no way to avoid it, but that doesn't mean that everyone is going to be able to be acclimated to zero-g. Not everyone can ride in a car without getting motion sickness despite years of acclimation and medication to help. Regardless, I don't feel like arguing what people may or may not enjoy.

Which is easier? Transporting over rough terrain? Paving highways? Or running cables?

I don't see how it gets much easier than throwing your cargo in the back of a truck and driving down the road to the next city.

We spend years learning to pilot spacecraft because there are so few of them and they perform several, extremely different roles (launch, orbiter, reentry). And who says you even need a pilot for an inter-asteroid cable car?

We've had aircraft for over a century and people are still required to go through years of training before being handed a license. I highly doubt spacecraft are somehow going to require significantly less training, especially when just landing/docking is just as dangerous as aircraft landings are.

 

[Drakkith]

When it comes to the vacuum and Mars, we're talking about the difference 0 and 0.6 percent of Earth's mean sea level pressure. And working in space doesn't necessarily mean working in freefall conditions. If there's work that's best performed under acceleration, you spin it. But I imagine a good deal of work with very massive components would be actually easier to perform in freefall.

I agree that certain things are easier in freefall, but I don't agree that it's inherently better than non-freefall. And I thought we were talking about building a settlement, in which case you wouldn't be able to use acceleration to help you build things since there's no settlement there to spin.

Not handwaving them away; any project off Earth is going to be considerably difficult compared to its terrestrial equivalent. I'm simply addressing the comparative difficulty of working in space vs working on an extra-terrestrial planet.

No, you're skipping over the cost and difficulties of a huge portion of the project. Think about what you're saying. You want to start a mining operation on a comet and then take everything you mine to fill a hollowed out asteroid. If you want to use Mars as an example, I can find plenty of O2 and water on Mars without needing to ever get into a rocket, completely negating any need to ship either of those to the colony.

It's going to have to be. There's no way to transport people off this planet to other destinations without them spending some time in freefall.

I agree that there's no way to avoid it, but that doesn't mean that everyone is going to be able to be acclimated to zero-g. Not everyone can ride in a car without getting motion sickness despite years of acclimation and medication to help. Regardless, I don't feel like arguing what people may or may not enjoy.

Which is easier? Transporting over rough terrain? Paving highways? Or running cables?

I don't see how it gets much easier than throwing your cargo in the back of a truck and driving down the road to the next city. Basic roads are not very difficult to build.

We spend years learning to pilot spacecraft because there are so few of them and they perform several, extremely different roles (launch, orbiter, reentry). And who says you even need a pilot for an inter-asteroid cable car?

We've had aircraft for over a century and people are still required to go through years of training before being handed a license. I highly doubt spacecraft are somehow going to require significantly less training, especially when just landing/docking is just as dangerous as aircraft landings are.

 

[Pete Cortez]

I agree that certain things are easier in freefall, but I don't agree that it's inherently better than non-freefall. And I thought we were talking about building a settlement, in which case you wouldn't be able to use acceleration to help you build things since there's no settlement there to spin.

Go to any construction site and you'll see all sorts of temporary structures and scaffolds used to aid in the project. Any project--in space or on Mars--is going to require similar prep stations.

No, you're skipping over the cost and difficulties of a huge portion of the project.

Yes, in both environments.

Think about what you're saying. You want to start a mining operation on a comet and then take everything you mine to fill a hollowed out asteroid.

Yes, and I'd need to set up extraction operations on Mars to acquire the same minimum mass of volatiles and materials.

If you want to use Mars as an example, I can find plenty of O2 and water on Mars without needing to ever get into a rocket, completely negating any need to ship either of those to the colony.

Except of course the rocket to get bodies and equipment down on the surface in the first place.

I agree that there's no way to avoid it, but that doesn't mean that everyone is going to be able to be acclimated to zero-g. Not everyone can ride in a car without getting motion sickness despite years of acclimation and medication to help. Regardless, I don't feel like arguing what people may or may not enjoy.

I think we can both agree that there's not much fruit in comparing vistas of completely alien environments at this point.

I don't see how it gets much easier than throwing your cargo in the back of a truck and driving down the road to the next city. Basic roads are not very difficult to build.

Slinging cable is even easier to do. Hell, in space we're talking about a process not dissimilar from TPing the neighbor's tree on Halloween. In a vacuum. In freefall. With giant, hundreds of kilometers long spools of cable.

We've had aircraft for over a century and people are still required to go through years of training before being handed a license. I highly doubt spacecraft are somehow going to require significantly less training, especially when just landing/docking is just as dangerous as aircraft landings are.

We've had extraterrestrial rovers for over a century and people are still required to go through years of training before operating them. Let's face it, right now taking a dump in space involves training. We can't just say that erecting, maintaining and employing overland transportation on a planet with a third of Earth's gravity and 0.6 percent of its ground level atmospheric pressure is going to be a piece of cake. Also, when the pipeline for new operators is filled to the brim, it often takes longer to get certified than absolutely necessary. Commercial pilots, for example, are at the mercy of weather, finances, the availability of training aircraft, and demand for new aviators when filling in their logbook. Otherwise, indoc, classroom instruction and the 200-400 hours of flying time required to pick up all the certifications required to fly professionally could be completed in a matter of weeks.