Engineering Habitats for the Moon and Mars
structuremag.org
structuremag.org
For the smokers sent to Mars living in flimsy shelters this'll decrease their lifetime odds of dying from cancer compared to smoking two packs a day and staying on Earth.
This article like so many others describes designs for Mars habitats that are optimized for being accepted under NASA's strict safety rules, and it's an organization run by safety-obsessed bureaucrats.
I predict that once the second space race kicks off in earnest these unpractical restrictions are going to be quickly dismissed, because NASA's going to have to compete with e.g. China which'll likely use much simpler designs because they're realistic about their risk assessments.
1. https://www.space.com/21813-mars-one-colony-space-radiation....
(Not actually joking ... 18th century America consumed very large quantities of alcohol and tobacco).
> Within the root network, residents will have
> their private spaces protected from harsh
> radiation, meteoroid impact, and thermal
> environment.
> [...]
> The radiation protection will be enhanced by
> the inclusion of a layer in the shield
> consisting of a water reservoir.
> [...]
> This [regolith layer] layer can also serve
> as shielding from solar and cosmic radiation
> fields. The thickness of the layer would be
> variable, with thicker construction in the
> directions with greater sun exposure.
> [...]
> The weight of the regolith sandbags will
> provide protection from radiation and
> impact;
I bet there'd be a lot of people with short life expectancies who'd want to spend what they have left embarking on the greatest adventure in history.
Simpler than a water reservoir and regolith sandbags? The former is required anyways, since people will need water, and the later is about as simple as it comes (we use sandbags here on earth all the time for impromptu buildings).
Even just regolith sandbags are going to suck, instead of just having your roof be a simple pressure vessel it's now going to also have to withstand tons of sandbags and water tanks.
And that's before we get to the problem of trying to either ship all of this extra water mass over, or trying to mine it locally, or the construction logistics of piling up hundreds of tons of sand.
All of this will be needed eventually, but it's absurd that NASA is trying to get in the way of Mars colonization by setting these overly conservative safety requirements which'll significantly hinder initial colonization efforts.
Also - the simple designs have a problem here- they are not easily repairable with local materials. And as you can see on any airplane- those simple soda can designs- wear out pretty fast, if pressure changes regularly. So, yeah- its a simpler design as in - simpler on earth to maintain, but on Mars its going to blow up like Mark Rodneys Potatoefarm from stress around the airlocks.
The process of colonizing Mars should be that we realistically look at how much payload we can send up there, how much it costs, and then we find some adventurers willing to take risks to go.
I don't think it's unrealistic to say as a first approximation that the first people to land on Mars can expect a 10% chance of dying by just trying to get there, and 30% of dying early due to some complications, e.g. radiation exposure.
Those would have been fantastic odds when the New World was first colonized, or when soldiers landed on Omaha beach. Colonizing Mars needs to be looked at like that, not in terms of sending some government employee into a dangerous situation, as if though they're going to repair some machinery here on Earth.
Instead, NASA views their rules on safety as immutable, and is coming up with designs for habitats and ships to satisfy those rules, without ever having the discussion that perhaps those rules are unreasonable given the endeavour.
"I do think getting good at digging tunnels could be really helpful for Mars. For sure there's going to be a lot of ice mining on Mars, and mining in general to get raw materials. You can build a tremendous amount underground with the right boring technology on Mars. So I do think there is some overlap in that technology development arena."
The weight of the dirt counteracts the air pressure and protects against radiation and temperature variation. The bricks provide a rigid compressive structure to maintain the shape and hold up the dirt.
The liner doesn't have to be particularly strong, just resistant to accidental tears. Theoretically, the brick dome could be omitted if you can exactly balance the weight of the dirt with internal air pressure, but that seems kind of risky (and every time the internal pressure fluctuates slightly, the dome gets a little smaller as the dirt settles).
The hard parts of this plan are a) how do you get/make thousands of bricks? and b) how do you do all the excavation and assembly? It would be great if we could get robots to do the whole thing and have a habitat ready before humans arrive on the scene, but with current tech a lot of the work might have to be done manually by guys in space suits with construction equipment. I suppose once you have one habitat, it's a lot easier to build a second one next to it.
http://www.sciencemag.org/news/2015/05/space-radiation-may-d...
After letting the mice rest for 6 weeks, the team put them through a battery of cognitive tests, including a task that required the rodents to distinguish between familiar and novel objects, such as toys. The mice hammered by radiation were “severely compromised” on several measures compared with an unexposed control group, Limoli says. Control mice, for example, spent more time sniffing around a new item placed in their cages than investigating familiar objects—a sign that their ability to react to novelty was intact. Irradiated mice, in contrast, spent equal time exploring new and old items, suggesting their ability to learn and remember new information about their environment had been impaired.
Talk of mars colonization is riddled with myopic assumptions about something we barely understand. Focusing on those few issues we may have in hand to the exclusion of the many critical unsolved problems is troubling.
They also mention that is not a showstopper and that it can potentially be countered with entertainment and exercise.
It also remains to be seen what the effect is like on humans. Might be negligible on a mars trip.
A more realistic approach to mitigating the issue is in my opinion to have rotating crews. They would spend most of their time in underground shelters, and only some minor fraction of their time doing surface work. Advances in medicine, specifically in regard to cancer, along with minimizing exposure time, is what I believe will make the risk low enough to be within acceptable bounds.
This is in large part why I think that Mars is continent upon offworld mining and construction industry, rather than the other way around.
They're typically not qualified for much of the labor needed in a colony, but that's another problem. We only need a tiny percentage of the eligible. Some people really have different priorities than confort and longevity. Many of them are risking their lives on Everest, for much less.
If there was no other way, as it frankly was in the age sail, and human lives simply had to be the currency of progress then so be it. We don’t live in those times, and we definitely have options other than sacrificing some people; they’re just more expensive, difficult options.
I think something around this approach is the way to go.
http://www.nss.org/settlement/moon/library/LB2-303-Inflatabl...
https://space.stackexchange.com/questions/4678/how-far-can-y...
a 100+ MPH impact on earth would require a survival capsule too tough for normal purposes so we use parachutes. However a 45 MPH impact is unsurvivable if naked but a car like structure for an elevator means you could likely walk away from a mining accident where your elevator falls down a mineshaft on the moon. Its likely lunar mineshaft elevators will require little more than extensive crumple zones in the floor, unlike on earth. Also on the earth stuntmen require weird inflated balloons to break their fall but on the moon a terminal velocity of only 45 MPH means something like a ball pit or a relatively shallow (compared to earth...) water pool would make falls survivable.
I'm too lazy to run the math to figure out the maximum gravity where a human could fall from a very far height and hit the ground at less than a survivable 10 MPH or whatever is defined as survivable.
https://space.stackexchange.com/questions/4678/how-far-can-y...
The big mistake of course is the lunar atmosphere is, as an engineering approximation, 1e-15 atm not 1.00 atm.
In practice its interesting to think about a micrometeor strike hitting a large structure, given the very low mass and low structural stability of a random rock chunk vs aerodynamic forces, it would blast clean thru the ceiling, then shatter and lose velocity very quickly down to sonic range or perhaps far below. Something like a giant balloon stretched over a tall crater would be reasonably survivable when hit by a meteor. Decades ago how to repair the tiny slow leak would be a major puzzle, today its just a boring job for an autonomous drone. Possibly the assumption in the article is if the roof is thousands of meters overhead and a meteor breaches the roof, it'll hit a human in the head at 45 MPH, which is quite survivable if the colonists wear construction hard hats but not so good out in the open. Sleep with a roof over your head, even rather minimal, and you probably won't wake up dead, if the balloon ceiling is far enough overhead.
The abstract says that Martian meteorites having a mass greater than 1 metric ton hit the surface with essentially their space velocity, undecelerated. Those with mass less than 10 grams hit at terminal velocity, whatever that is for Mars. In between, I suppose there's a continuum of impact velocities depending on the mass.
[1] http://adsabs.harvard.edu/full/1969PASP...81..399D (paywalled, but they show you the first page with the abstract, which tells the tale)
I'm a big fan of space, but I don't see me going there until something better than rockets are invented and all the other many problems are solved so I can just sit at a nice coffee shop and enjoy the view.
Also note, this makes John Carmack's contribution to space colonization significant.
we could drill a few holes into lava tubes for example https://en.wikipedia.org/wiki/Martian_lava_tube and direct light into it for something a bit more elaborate.
These units are generally much more pleasant to remember and work with, even despite the code using empirical design equations that require SI units