Nowadays, depending on the measure, almost everything has satellite coverage. Surface stations aren't as extensive, but they're pretty extensive, and there's been huge amounts of work to correlate surface and satellite measurements. But it seems here like we're drifting off topic: the topic was, when someone finds errors in old data, should we just ignore it? Because it sounds like you were arguing that we should.
Errors can be demonstrated and old records thus corrected. But missing data can't be conjured out of thin air. So what exactly do you want? People not to correct errors when they find them? Or people to find a way to conjure nonexistent data out of thin air? What exactly do you want?
Dr. Hugh Willoughby, former head of NOAA's Hurricane Research Division, had this to say about the winds measured in Super Typhoon Nancy and the other high-end typhoons from this list from the 1960s:
"I would not take the winds seriously because reconnaissance meteorologists estimated them visually. A decade later when I flew with the VW-1 hurricane hunters, we had the same Doppler system used to measure the winds of Typhoon Nancy. It tracked the aircraft motion relative to the (possibly moving) sea surface. It couldn't get a coherent signal in high winds because the beam reflected from both the actual surface (whatever that is) and blowing spray. Visual estimates are dubious because the surface (under the eyewall!) is hard to see unless you are flying below cloud base (200-300 m) and also because appreciably above 115 mph, it's completely white with blowing spray. We used to think that we could estimate stronger winds from the decreasing coverage of slightly greenish patches where the spray was thinner. I now think that we were kidding ourselves. In those days the distinctions among wind gust, sustained one-minute winds, etc., were less well defined than they are now. So we may never know the 1960s reconnaissance data really means!"
At the same time, we should keep in mind that not all hurricanes are sampled while at peak strength. Satellite methods of estimating intensity, such as the Dvorak technique, cannot capture the most extreme peak winds and central pressures found in storms such as Patricia and Wilma. It is possible that previous hurricanes, such as the 1935 Labor Day hurricane that devastated the Florida Keys, had intensification rates and peak winds on par with Patricia. The bottom line is that Patricia is at the very highest end of what we can expect in terms of a small, extremely intense hurricane.
This is the nature of reality. Your data gets better and better with time. You don't whine when you learn that some old records may have been in error, just like you don't whine when you learn that there might have been past records that weren't measured as such due to insufficient data.
(For the record and in a similar vein, the "world's hottest temperature in Al-Azzyah Libya" thing is also considered to be erroneous. But that doesn't mean that before we had such good temperature-measuring coverage that there weren't super-hot temperatures in the past - just that that one is almost assuredly wrong)
It'll be climate if the number of hurricanes keeps increasing,
Well... sort of. It's climate if any statistical property of hurricanes undergoes any statistical shift. Climate is the signal. Weather is the noise. It's like, say, driving home from work. Let's say it normally takes you an average of 20 minutes to drive home from work. Your numbers may go 17, 21, 14, 29, 19, 16, 26, 18, etc depending on local conditions... but the average is 20. But when a statistically significant sampling of drives starts averaging out higher - say, 27, 20, 21, 34, 20, 26, 31, etc... the underlying baseline has changed. The noise still exists, but it's on top of a different signal.
In terms of hurricanes, a warming average climate does not inherently mean "more hurricanes". Hurricanes from due to a complicated series of circumstances - some of which we understand well (like sea surface temperatures), some which we don't (like African dust). There's not only sea surface temperatures but the depths to which it exends, wind shear, dry air, and literally dozens of other factors. Not all of the changes that are associated with a warming planet encourage hurricanes - some discourage them. And the impacts can vary from one hurricane basin to another.
The North Atlantic basin, which most Americans care most about, has two strongly opposing effects in a warming world: increasing ocean heat versus increasing wind shear. Wind shear is death to hurricanes. The airflow patterns that fuel a hurricane require that the core be vertically aligned, so when you shear it horizontally, it fails to be able to power itself. Larger hurricanes can somewhat protect themselves against it, at the cost of declining intensity, but smaller storms get torn to shreds. It combines with dry air to worsen its effect, funneling the dry air into the core (dry air = subsidence = shutting off upflow-driven storms like hurricanes).
How these two factors ultimately play out is very difficult to predict, and particularly in the North Atlantic. The number of hurricanes per year in the North Atlantic Basin ranges from zero to dozens. And where they impact varies widely as well - the US can get nailed many times by powerful storms, or they can get hit by nothing at all. The general expectation is "mixed": that the increasing wind shear may reduce the total number of storms and will almost certainly rip apart more "vulnerable" storms - but that when conditions are right (as wind shear is constantly varying, and there are always times and places that there is little to none), storms will appear faster, grow faster, and reach higher top speeds.
That said, again, hurricanes are very complicated systems to model and predict, so it's hard to make predictions on this front with too much confidence.
On the other hand, when you're subjecting planets to increased tidal forces, you're also unlocking a new source of energy: tidal flexure heating. You're bending a massive chunk of rock into a new shape, there's a tremendous amount of heat released in the process (you're probably also tidal locking it if it wasn't already).
Counterproductive if the body ends too close to the star, but useful if the body ends up too far from the star. Unless it's to the extremes covered in this article where the tidal forces are sufficient to rip the planet into a ring.
It was announced in May 2014 that the flight-qualified version of the SuperDraco engine is fully printed, and is the first fully printed rocket engine. In particular, the engine combustion chamber is printed of Inconel, an alloy of nickel and iron, using a process of direct metal laser sintering, and operates at a chamber pressure 6,900 kilopascals (1,000 psi) at a very high temperature. The engines are contained in a printed protective nacelle to prevent fault propagation in the event of an engine failure.[14][15][1] The engine completed a full qualification test in May 2014, and is slated to make its first orbital spaceflight in 2015 or 2016.[1]
The ability to 3D print the complex parts was key to achieving the low-mass objective of the engine. According to Elon Musk, "Itâ(TM)s a very complex engine, and it was very difficult to form all the cooling channels, the injector head, and the throttling mechanism. Being able to print very high strength advanced alloys... was crucial to being able to create the SuperDraco engine as it is."[16]
The 3D printing process for the SuperDraco engine dramatically reduces lead-time compared to the traditional cast parts, and "has superior strength, ductility, and fracture resistance, with a lower variability in materials properties."[5]
According to Elon Musk, cost reduction through 3D printing is also significant, in particular because SpaceX can print an hourglass chamber where the entire wall consists of interval cooling channels, which would be impossible without additive manufacturing.[17]
... you can work 3d printing into a higher percentage of your stories than this. Here, let me help:
Experts Chime In To Explain Fukushima Thryoid Cancer Concerns; Possibility To 3D Print New Thyroids? Samsung Demos PCIe NVMe SSD At 5.6 GB Per Second, 1 Million IOPS - Can Store Over 100k Printable 3D Models DARPA Program Targets Image Doctoring, Hasn't Yet Tackled 3D Printed Duplicates Oracle Fixes Java Vulnerability Used By Russian Cyberspies With 3D-Printed Keyboard We Assume Based On No Evidence Should Japan Restart More Nuclear Power Plants And Retrofit Them With 3D-Printed Control Rods? Only 8% of the Universe's Habitable Worlds Have Formed So Far; Remainder Awaiting Jumbo-Sized MakerBot.
Ack, sorry, that should read "130 mph". I converted it to mph for you but still wrote it as m/s:P
Most of the hiking near Reykjavík is pretty safe.. it's mainly the dumb ones who go climbing on flowing glaciers or going into ice caves without a guide that are being Darwin Award contenders. Most of what you'll walk on is either solid bedrock or well-compacted glacial sediments. Near canyons or at the edges of cliffs you find scree slopes... in general these are safe, even if you slide (though you can potentially go a *long* way down), but don't trust boulders near/on them, they're often loose or, in the case of bedrock "rotten", crumbling rather easily (hence the scree). And of course be careful with scree slopes that have cliffs partway down, obviously. And avoid scree slopes or other crumbly areas shortly after a thaw or a period of very heavy rains, this is when they "run". Oh, and in geothermal areas, don't walk up to the edge of any geothermal feature containing hot water or mud. The edges aren't stable, a few people fall in and get burned every year. If you want to bathe in a non-touristed geothermal feature, you don't do it where the water comes up, you do it where the water runs off. Usually people have to stack some rocks to make a small dam so it will pool, although sometimes nature does it for you.
All of that said, in the Reykjavík area, there really isn't that much that's risky - Esjan and her surrounding mountains / hills are fairly old (well, by Icelandic standards;) ) and for the most part well compacted - you can usually avoid even encountering bedrock except at the very tops if you want to. Another nice side effect of the age is that there's neat minerals - lots of chalcedony and neat zeolites in the Kjalarnes/Hvalfjörður area, basically from Esja on north. If you're a rockhound, look for bedrock at lower layers (such as those exposed by rivers at the bottom of a glacial valley) and check the rock and the scree below it. For chalcedony, train your eye for anything from "fogged-glass gray" to "blood red but not clinker/rust" or "deep green but not moss". For zeolites, look for bright white. Supposedly there's also plenty of pyrite here but I've never found any. Amygdules are common. Spherules can be found in some places. You can find calcite but in this part of the country it usually comes as masses or amygdules - good crystal specimens (iceland spar) are mainly found in the east. Oh, and you can find opal sometimes if you're lucky, although I've never found anything with play of color, just pure white.
Oh, as for getting lost: in gentle glacial valleys, follow the standard advice for finding civilization: go downhill, follow the rivers/streams, etc. But when there's a canyon, don't do this. Icelandic river canyons, even ones that start out easy, tend to frequently have the river pin up against cliffs - if you're down there, the climb up to get around a barrier can be staggeringly difficult. Take the high road around canyons - the canyon will eventually disappear, and you'll probably find some sign of civilization after it. One nice thing about Iceland: there's often cell reception even in wilderness areas (except the deep highlands). And we have excellent rescue services.
The concept actually kind of is what you linked to:) They inflate a dome and then spray a material that will harden onto it. The differences are that what they're spraying is water+fibers+aerogel rather than cement+water+rebar+aggregate, and the spraying is done from close range rather than long range. Bringing fibers + aerogel rather than cement + rebar is obviously a lot lighter, and the former combination gives you light (amplified in the living area by the fresnel lens shape) and increases the R-value. Rather than inflating foam for the next layer (insulation), they print (aka, spray) out aerogel + binder (again, it's lighter). Spraying at close range rather than long range (ala shotcrete) reduces the power requirements on the pumping system, gives greater control over the shape/accuracy (allowing for light concentration and greater structural strength with less material), and reduces the complications of water vaporizing or freezing en route to the skin (remember that we're dealing with Mars temperatures and pressures here).
But at a fundamental level, it's basically a proposal for a high-tech, Mars-adapted version of a monolithic dome.
The "prettiness" is just a side effect of printing with water and the fresnel lens effect; I don't think it's fair to penalize them for their design *also* being pretty. That said, I am in full agreement that it's good for your crew to have natural light... not just for saving power or growing plants, but also for their mental well being. These are people basically cooped up in a can on a dead world for months to years on end who can't get away from their coworkers even if they wanted to and don't get to see their families and friends... at least give them some sunlight.
Also, ask anybody who's served on a nuke boat in the navy, iron/steel is a far better radiation shield than water.
Depends highly on the type of radiation. Iron is actually a pretty terrible shield against neutrons, for example.
As far as general purpose shielding against solar radiation and GCR, things rich in hydrogen generally are the best option. You can boost their effectiveness by borating them, especially on the inner layers, to help absorb thermal neutron secondaries.
Water is not scarce on Mars, it's actually quite abundant.
You cannot just "press regolith into blocks", any more than you can just press sand into blocks. You can sinter it into (gas-permeable) bricks, but that takes a great amount of energy - vastly more than melting water. And you want to bring a gantry crane to Mars to stack them?
This is why most of the (decent) books about mars colonization involve living underground initially.
Oh great, not only do you want to ship in a gantry crane, you also want to ship in a tunnel borer!
Don't stop there, ship in a bucket wheel excavator to do your mining, and a trained elephant to boulders around on sleds!
This design does call for exactly that: bringing their own habitat and using martian materials as exterior coverings. There are three segments: the inner segment (living quarters) is the rocket that brought all of the building supplies there. It's surrounded by an aerogel dome for insulation. The ice dome for radiation shielding is outside of that. There are three separate levels of air locks in the design.
It does have a greenhouse built in, yes. So you could grow potatoes there (unlike the approach used in the book, which wouldn't actually work;) )
One thing that the ice house site mentions in passing, without going into the implications, is that the shape of the ice shell will act as a fresnel lens. One of the neat aspects about that is that you can have it function as basically a passive solar concentrator, boosting the effective solar constant in the greenhouse/living area..
They certainly warrant investigation and might ultimately prove useful, but they also present about as hazardous, difficult to access terrain as one could possibly imagine. And are a total unknown at this point in time.
Why is it so hard for people to RTFA, when it's provided in the post you're responding to?
3D Printing with Ice
Ice habitats on Earth and 3D Printing with ice are not without precedent. In consultation with our Team’s expert scientific advisors, astrophysicists, geologists, structural engineers and renowned 3D printing experts, we have achieved positive experimentation with one to one ice printing and successfully analyzed structural models.
Through an understanding of the physics of phase change and the temperature and pressure conditions of the Martian environment, as well as an understanding of the physical deposition techniques required we've designed a process to turn subsurface ice into water vapor, vapor used to deposit liquid water, in an environment cold enough to print a form in solid ice.
Making & Climbing the Ice Wall
The iBo is designed to deposit layers of ice with a low-volume, close-range nozzle that ensures that any water that freezes mid-trajectory melts and refreeze instantaneously via the energy of its impact (a contact weld).
It's not an obscure concept. And they've done test prints in a simulated Mars environment.
Any more questions? If so, make sure you read the design document first before asking them.
Ice isn't known for its structural properties, its prone to cracking, temperature sensitive & its not overly strong.
Which is why they're not printing out of pure ice. They're printing out of a mixture of ice, aerogel and reinforcing fibers. The *are* proposing a modern equivalent of pykrete.
but that's not going to stop it from trying to sublimate every time the sun hits it
Of course not. The EFTE exterior membrane onto which the ice is printed is what does that.
or melting if you accidentally set one of the many heat sources necessary to keep your crew alive too close to it.
Your crew doesn't live in that dome. They don't even live in the next dome inward from it (which is made of aerogel). They live inside the rocket which took the construction supplies and hardware there, located in the center of the aerogel dome. You have three spaces. The inner-most is the rocket-supplied living space (after having all of the aerogel, reinforcing fiber, etc unloaded from it) - bedrooms, kitchen, bathroom, lab, etc. The next layer out, the aerogel dome, is "outside" space at moderate temperatures, which acts as a greenhouse for growing plants and gives people place to walk around comfortably rather than being cramped inside the launched living area all the time. Outside that is the cold but still pressurized and radiation-blocking ice dome, where people can prep for EVAs, park vehicles and be as close to "walking around unsuited on Mars" as is possible for a human. Each layer provides redundancy in the event of a leak.
Its an interesting approach; I recommend you read the design document.
So your basic argument is "don't worry about how hard the habitat you want to build is, just make sure that you can fit a piece of furniture anywhere in it"?
If so, I've got a wall to hit my head against.
Curved walls on the radiation shielding/pressure vessel are the best shape for the walls of a radiation-shielding pressure vessel. We're not talking about someone's bedroom here, we're talking about the thing that stops your bedroom from getting fried by high energy protons. And you want to complicate the construction process - both the ability of the printers to traverse it, and the complexity of the membrane - so that simply your *shield* (not your living space) isn't round? And again, as for the bedrooms themselves, the shapes are to be dictated by the shape of the rocket (cylinder, not dome nor box) because, well, what you're sending to Mars is a rocket, and it's far, far easier to make something complex (like the actual area a person will be living in and all of the fixtures therein) on Earth than to try to build it on Mars. And if that means rounded external walls, people will live with rounded walls, just like they've done in every habitat we've ever launched into space.
I did not say because it's a "natural" shape. I said because it's the ideal shape for maximizing internal area while reducing surface area, and it's the shape naturally reached by inflating a membrane (which is what this concept is based on). Furthermore, "internal space" != "living space". The outer shell is a pressure vessel and radiation shielding. This creates a cold but breathable and pressurized area which can function as storage space, a place for holding external equipment, an EVA prep area, etc. The next shell in is the insulation shell (also with its own airlock, adding redundancy). Inside this (also domed) structure is a greenhouse / livable "outdoor" area for people to spend time in. Plants don't give a rat's arse what shape greenhouse they're being grown in, and you don't put beds and the like in the greenhouse. The actual living area isn't a dome. It's a cylinder. Why? Because it's the rocket sent from Earth, and rocket housings are cylindrical. You deal with what you've got.
You clearly have not read the construction process proposed for building these domes, hence your comments are not applicable. Please read the proposed construction method, *then* come back here and discuss it. Your "straight walls with corners" approach would require a far more complicated wheel assembly than the one that they use to go along curved, cornerless walls, which is akin to a common assembly used by roller coasters to hang onto a track. When was the last time you saw a roller coaster traversing a sharp 90 degree corner? As for the top of the dome, each of the printing bots has an arm from which the material (mostly water, but also aerogel and reinforcing fibers) is sprayed.
Speaking of "chaning down buildings", I had 130m/s winds on my land last spring. Ripped down my entire windbreak (posts all snapped at the base) and flipped my steel crate full of steel beams, a huge stack of timber, dozens of large window panes, a cast iron stove, and numerous other heavy objects. On the other side of the river it flipped another loaded crate and ripped down the middle of an old concrete stables. The stables was in bad shape, but still... At least my crate is underground now.
Fall usually isn't too bad. But late winter/early spring can be pretty unreal. Last winter/spring we hardly got a break, it was one windstorm after the next, no more than 3 days between them, usually less.
If you're driving through the Hvalfjörður area and turn into the first valley on the right (Miðdalur) and see a gate with runes and a crate buried into the landscape to look like the entrance to a mine, that'd be my land.;)
Best of luck with your simple to operate and maintain, affordable-to-launch Martian tunnel borer. And I'm sure you'll only go through oh-so-predictable strata.
It will reduce the transparency. But Mars also undergoes wind scouring events - which is why Opportunity is still roving on Mars to this day.
Good transparency isn't a key aspect of the design. The basic issue is, you need radiation shielding from something, ideally something local. What's easier to work with that's local on Mars than water? Yeah, what's on Mars is really more like a salty, silty frozen muck than the pure fresh water ice that most people picture. But turning that to consistent-quality building material is assuredly easier than doing the same with bedrock, regolith, or whatnot. And much easier to spray/cast/etc while minimizing the amount of material you have to bring from Earth to do so.
A sphere has the minimum ratio of surface area (and thus material) to volume. It's also the shape you get when you inflate the simplest shape of balloon to act as the surface you're going to print against. Modifying the ideal sphere for a number of practical constraints leads to a more domed shape as in the winning design.
Corners are also an impediment to a robot designed to ride a self-printed track around the inside of a wall, as in the design.
Insulation does not regulate temperature. A closed box needs to have active temperature regulation for long term use.
You do have active temperature regulation. It's called "thousands of square meters of external surface area convecting with the atmosphere and radiating into space". It's a well pretty known thing that things on Mars tend to get cold. Usually there's far more challenge to have them not get too cold than to cool them down - hence, even Mars missions that don't use RTGs still tend to use smaller radiothermal heaters.
Any temperature gradient moving across the ice (in the above, -50C to -60C) means heat loss. The greater the gradient, the faster the heat loss - if you wanted more heat loss you could reduce the insulation and bump the inside of the ice's temperature up to say -10C and get a 50-degree delta-T instead of a 10-degree delta-T and thus 5x higher heat flow. But again, with this large of a structure, "getting too hot" is not your problem. Avoiding getting too cold is.
Slashdot Mirror
Nowadays, depending on the measure, almost everything has satellite coverage. Surface stations aren't as extensive, but they're pretty extensive, and there's been huge amounts of work to correlate surface and satellite measurements. But it seems here like we're drifting off topic: the topic was, when someone finds errors in old data, should we just ignore it? Because it sounds like you were arguing that we should.
Errors can be demonstrated and old records thus corrected. But missing data can't be conjured out of thin air. So what exactly do you want? People not to correct errors when they find them? Or people to find a way to conjure nonexistent data out of thin air? What exactly do you want?
This is the nature of reality. Your data gets better and better with time. You don't whine when you learn that some old records may have been in error, just like you don't whine when you learn that there might have been past records that weren't measured as such due to insufficient data.
(For the record and in a similar vein, the "world's hottest temperature in Al-Azzyah Libya" thing is also considered to be erroneous. But that doesn't mean that before we had such good temperature-measuring coverage that there weren't super-hot temperatures in the past - just that that one is almost assuredly wrong)
Well... sort of. It's climate if any statistical property of hurricanes undergoes any statistical shift. Climate is the signal. Weather is the noise. It's like, say, driving home from work. Let's say it normally takes you an average of 20 minutes to drive home from work. Your numbers may go 17, 21, 14, 29, 19, 16, 26, 18, etc depending on local conditions... but the average is 20. But when a statistically significant sampling of drives starts averaging out higher - say, 27, 20, 21, 34, 20, 26, 31, etc... the underlying baseline has changed. The noise still exists, but it's on top of a different signal.
In terms of hurricanes, a warming average climate does not inherently mean "more hurricanes". Hurricanes from due to a complicated series of circumstances - some of which we understand well (like sea surface temperatures), some which we don't (like African dust). There's not only sea surface temperatures but the depths to which it exends, wind shear, dry air, and literally dozens of other factors. Not all of the changes that are associated with a warming planet encourage hurricanes - some discourage them. And the impacts can vary from one hurricane basin to another.
The North Atlantic basin, which most Americans care most about, has two strongly opposing effects in a warming world: increasing ocean heat versus increasing wind shear. Wind shear is death to hurricanes. The airflow patterns that fuel a hurricane require that the core be vertically aligned, so when you shear it horizontally, it fails to be able to power itself. Larger hurricanes can somewhat protect themselves against it, at the cost of declining intensity, but smaller storms get torn to shreds. It combines with dry air to worsen its effect, funneling the dry air into the core (dry air = subsidence = shutting off upflow-driven storms like hurricanes).
How these two factors ultimately play out is very difficult to predict, and particularly in the North Atlantic. The number of hurricanes per year in the North Atlantic Basin ranges from zero to dozens. And where they impact varies widely as well - the US can get nailed many times by powerful storms, or they can get hit by nothing at all. The general expectation is "mixed": that the increasing wind shear may reduce the total number of storms and will almost certainly rip apart more "vulnerable" storms - but that when conditions are right (as wind shear is constantly varying, and there are always times and places that there is little to none), storms will appear faster, grow faster, and reach higher top speeds.
That said, again, hurricanes are very complicated systems to model and predict, so it's hard to make predictions on this front with too much confidence.
On the other hand, when you're subjecting planets to increased tidal forces, you're also unlocking a new source of energy: tidal flexure heating. You're bending a massive chunk of rock into a new shape, there's a tremendous amount of heat released in the process (you're probably also tidal locking it if it wasn't already).
Counterproductive if the body ends too close to the star, but useful if the body ends up too far from the star. Unless it's to the extremes covered in this article where the tidal forces are sufficient to rip the planet into a ring.
I look forward to the next release, Xenophobic Xenu. And they say that there's going to be some big changes with Yogic Yosafbridge.
I don't know if Tesla 3d prints anything, but SpaceX's SuperDraco thrusters are 3d printed. :)
... you can work 3d printing into a higher percentage of your stories than this. Here, let me help:
Experts Chime In To Explain Fukushima Thryoid Cancer Concerns; Possibility To 3D Print New Thyroids?
Samsung Demos PCIe NVMe SSD At 5.6 GB Per Second, 1 Million IOPS - Can Store Over 100k Printable 3D Models
DARPA Program Targets Image Doctoring, Hasn't Yet Tackled 3D Printed Duplicates
Oracle Fixes Java Vulnerability Used By Russian Cyberspies With 3D-Printed Keyboard We Assume Based On No Evidence
Should Japan Restart More Nuclear Power Plants And Retrofit Them With 3D-Printed Control Rods?
Only 8% of the Universe's Habitable Worlds Have Formed So Far; Remainder Awaiting Jumbo-Sized MakerBot.
Come on, Slashdot, you can do it!
Ack, sorry, that should read "130 mph". I converted it to mph for you but still wrote it as m/s :P
Most of the hiking near Reykjavík is pretty safe.. it's mainly the dumb ones who go climbing on flowing glaciers or going into ice caves without a guide that are being Darwin Award contenders. Most of what you'll walk on is either solid bedrock or well-compacted glacial sediments. Near canyons or at the edges of cliffs you find scree slopes... in general these are safe, even if you slide (though you can potentially go a *long* way down), but don't trust boulders near/on them, they're often loose or, in the case of bedrock "rotten", crumbling rather easily (hence the scree). And of course be careful with scree slopes that have cliffs partway down, obviously. And avoid scree slopes or other crumbly areas shortly after a thaw or a period of very heavy rains, this is when they "run". Oh, and in geothermal areas, don't walk up to the edge of any geothermal feature containing hot water or mud. The edges aren't stable, a few people fall in and get burned every year. If you want to bathe in a non-touristed geothermal feature, you don't do it where the water comes up, you do it where the water runs off. Usually people have to stack some rocks to make a small dam so it will pool, although sometimes nature does it for you.
All of that said, in the Reykjavík area, there really isn't that much that's risky - Esjan and her surrounding mountains / hills are fairly old (well, by Icelandic standards ;) ) and for the most part well compacted - you can usually avoid even encountering bedrock except at the very tops if you want to. Another nice side effect of the age is that there's neat minerals - lots of chalcedony and neat zeolites in the Kjalarnes/Hvalfjörður area, basically from Esja on north. If you're a rockhound, look for bedrock at lower layers (such as those exposed by rivers at the bottom of a glacial valley) and check the rock and the scree below it. For chalcedony, train your eye for anything from "fogged-glass gray" to "blood red but not clinker/rust" or "deep green but not moss". For zeolites, look for bright white. Supposedly there's also plenty of pyrite here but I've never found any. Amygdules are common. Spherules can be found in some places. You can find calcite but in this part of the country it usually comes as masses or amygdules - good crystal specimens (iceland spar) are mainly found in the east. Oh, and you can find opal sometimes if you're lucky, although I've never found anything with play of color, just pure white.
Oh, as for getting lost: in gentle glacial valleys, follow the standard advice for finding civilization: go downhill, follow the rivers/streams, etc. But when there's a canyon, don't do this. Icelandic river canyons, even ones that start out easy, tend to frequently have the river pin up against cliffs - if you're down there, the climb up to get around a barrier can be staggeringly difficult. Take the high road around canyons - the canyon will eventually disappear, and you'll probably find some sign of civilization after it. One nice thing about Iceland: there's often cell reception even in wilderness areas (except the deep highlands). And we have excellent rescue services.
The concept actually kind of is what you linked to :) They inflate a dome and then spray a material that will harden onto it. The differences are that what they're spraying is water+fibers+aerogel rather than cement+water+rebar+aggregate, and the spraying is done from close range rather than long range. Bringing fibers + aerogel rather than cement + rebar is obviously a lot lighter, and the former combination gives you light (amplified in the living area by the fresnel lens shape) and increases the R-value. Rather than inflating foam for the next layer (insulation), they print (aka, spray) out aerogel + binder (again, it's lighter). Spraying at close range rather than long range (ala shotcrete) reduces the power requirements on the pumping system, gives greater control over the shape/accuracy (allowing for light concentration and greater structural strength with less material), and reduces the complications of water vaporizing or freezing en route to the skin (remember that we're dealing with Mars temperatures and pressures here).
But at a fundamental level, it's basically a proposal for a high-tech, Mars-adapted version of a monolithic dome.
The "prettiness" is just a side effect of printing with water and the fresnel lens effect; I don't think it's fair to penalize them for their design *also* being pretty. That said, I am in full agreement that it's good for your crew to have natural light... not just for saving power or growing plants, but also for their mental well being. These are people basically cooped up in a can on a dead world for months to years on end who can't get away from their coworkers even if they wanted to and don't get to see their families and friends... at least give them some sunlight.
Depends highly on the type of radiation. Iron is actually a pretty terrible shield against neutrons, for example.
As far as general purpose shielding against solar radiation and GCR, things rich in hydrogen generally are the best option. You can boost their effectiveness by borating them, especially on the inner layers, to help absorb thermal neutron secondaries.
Water is not scarce on Mars, it's actually quite abundant.
You cannot just "press regolith into blocks", any more than you can just press sand into blocks. You can sinter it into (gas-permeable) bricks, but that takes a great amount of energy - vastly more than melting water. And you want to bring a gantry crane to Mars to stack them?
Oh great, not only do you want to ship in a gantry crane, you also want to ship in a tunnel borer!
Don't stop there, ship in a bucket wheel excavator to do your mining, and a trained elephant to boulders around on sleds!
This design does call for exactly that: bringing their own habitat and using martian materials as exterior coverings. There are three segments: the inner segment (living quarters) is the rocket that brought all of the building supplies there. It's surrounded by an aerogel dome for insulation. The ice dome for radiation shielding is outside of that. There are three separate levels of air locks in the design.
It does have a greenhouse built in, yes. So you could grow potatoes there (unlike the approach used in the book, which wouldn't actually work ;) )
One thing that the ice house site mentions in passing, without going into the implications, is that the shape of the ice shell will act as a fresnel lens. One of the neat aspects about that is that you can have it function as basically a passive solar concentrator, boosting the effective solar constant in the greenhouse/living area..
They certainly warrant investigation and might ultimately prove useful, but they also present about as hazardous, difficult to access terrain as one could possibly imagine. And are a total unknown at this point in time.
Why is it so hard for people to RTFA, when it's provided in the post you're responding to?
It's not an obscure concept. And they've done test prints in a simulated Mars environment.
Any more questions? If so, make sure you read the design document first before asking them.
Which is why they're not printing out of pure ice. They're printing out of a mixture of ice, aerogel and reinforcing fibers. The *are* proposing a modern equivalent of pykrete.
Of course not. The EFTE exterior membrane onto which the ice is printed is what does that.
Your crew doesn't live in that dome. They don't even live in the next dome inward from it (which is made of aerogel). They live inside the rocket which took the construction supplies and hardware there, located in the center of the aerogel dome. You have three spaces. The inner-most is the rocket-supplied living space (after having all of the aerogel, reinforcing fiber, etc unloaded from it) - bedrooms, kitchen, bathroom, lab, etc. The next layer out, the aerogel dome, is "outside" space at moderate temperatures, which acts as a greenhouse for growing plants and gives people place to walk around comfortably rather than being cramped inside the launched living area all the time. Outside that is the cold but still pressurized and radiation-blocking ice dome, where people can prep for EVAs, park vehicles and be as close to "walking around unsuited on Mars" as is possible for a human. Each layer provides redundancy in the event of a leak.
Its an interesting approach; I recommend you read the design document.
So your basic argument is "don't worry about how hard the habitat you want to build is, just make sure that you can fit a piece of furniture anywhere in it"?
If so, I've got a wall to hit my head against.
Curved walls on the radiation shielding/pressure vessel are the best shape for the walls of a radiation-shielding pressure vessel. We're not talking about someone's bedroom here, we're talking about the thing that stops your bedroom from getting fried by high energy protons. And you want to complicate the construction process - both the ability of the printers to traverse it, and the complexity of the membrane - so that simply your *shield* (not your living space) isn't round? And again, as for the bedrooms themselves, the shapes are to be dictated by the shape of the rocket (cylinder, not dome nor box) because, well, what you're sending to Mars is a rocket, and it's far, far easier to make something complex (like the actual area a person will be living in and all of the fixtures therein) on Earth than to try to build it on Mars. And if that means rounded external walls, people will live with rounded walls, just like they've done in every habitat we've ever launched into space.
I did not say because it's a "natural" shape. I said because it's the ideal shape for maximizing internal area while reducing surface area, and it's the shape naturally reached by inflating a membrane (which is what this concept is based on). Furthermore, "internal space" != "living space". The outer shell is a pressure vessel and radiation shielding. This creates a cold but breathable and pressurized area which can function as storage space, a place for holding external equipment, an EVA prep area, etc. The next shell in is the insulation shell (also with its own airlock, adding redundancy). Inside this (also domed) structure is a greenhouse / livable "outdoor" area for people to spend time in. Plants don't give a rat's arse what shape greenhouse they're being grown in, and you don't put beds and the like in the greenhouse. The actual living area isn't a dome. It's a cylinder. Why? Because it's the rocket sent from Earth, and rocket housings are cylindrical. You deal with what you've got.
You clearly have not read the construction process proposed for building these domes, hence your comments are not applicable. Please read the proposed construction method, *then* come back here and discuss it. Your "straight walls with corners" approach would require a far more complicated wheel assembly than the one that they use to go along curved, cornerless walls, which is akin to a common assembly used by roller coasters to hang onto a track. When was the last time you saw a roller coaster traversing a sharp 90 degree corner? As for the top of the dome, each of the printing bots has an arm from which the material (mostly water, but also aerogel and reinforcing fibers) is sprayed.
Speaking of "chaning down buildings", I had 130m/s winds on my land last spring. Ripped down my entire windbreak (posts all snapped at the base) and flipped my steel crate full of steel beams, a huge stack of timber, dozens of large window panes, a cast iron stove, and numerous other heavy objects. On the other side of the river it flipped another loaded crate and ripped down the middle of an old concrete stables. The stables was in bad shape, but still... At least my crate is underground now.
Fall usually isn't too bad. But late winter/early spring can be pretty unreal. Last winter/spring we hardly got a break, it was one windstorm after the next, no more than 3 days between them, usually less.
If you're driving through the Hvalfjörður area and turn into the first valley on the right (Miðdalur) and see a gate with runes and a crate buried into the landscape to look like the entrance to a mine, that'd be my land. ;)
Slashdot eats the unicode "^3" character, among countless others :P
Best of luck with your simple to operate and maintain, affordable-to-launch Martian tunnel borer. And I'm sure you'll only go through oh-so-predictable strata.
It will reduce the transparency. But Mars also undergoes wind scouring events - which is why Opportunity is still roving on Mars to this day.
Good transparency isn't a key aspect of the design. The basic issue is, you need radiation shielding from something, ideally something local. What's easier to work with that's local on Mars than water? Yeah, what's on Mars is really more like a salty, silty frozen muck than the pure fresh water ice that most people picture. But turning that to consistent-quality building material is assuredly easier than doing the same with bedrock, regolith, or whatnot. And much easier to spray/cast/etc while minimizing the amount of material you have to bring from Earth to do so.
A sphere has the minimum ratio of surface area (and thus material) to volume. It's also the shape you get when you inflate the simplest shape of balloon to act as the surface you're going to print against. Modifying the ideal sphere for a number of practical constraints leads to a more domed shape as in the winning design.
Corners are also an impediment to a robot designed to ride a self-printed track around the inside of a wall, as in the design.
You do have active temperature regulation. It's called "thousands of square meters of external surface area convecting with the atmosphere and radiating into space". It's a well pretty known thing that things on Mars tend to get cold. Usually there's far more challenge to have them not get too cold than to cool them down - hence, even Mars missions that don't use RTGs still tend to use smaller radiothermal heaters.
Any temperature gradient moving across the ice (in the above, -50C to -60C) means heat loss. The greater the gradient, the faster the heat loss - if you wanted more heat loss you could reduce the insulation and bump the inside of the ice's temperature up to say -10C and get a 50-degree delta-T instead of a 10-degree delta-T and thus 5x higher heat flow. But again, with this large of a structure, "getting too hot" is not your problem. Avoiding getting too cold is.