Surviving a meteorite strike - a research proposal

Originally posted by ThorTso
Anything that leaves a crater 75 miles in diameter will have devastated and wiped out the entire planet IMO. I do not believe that anything could survive such an event. You would have to be very deep in the bowels of the earth to escape this. I think it would make any underground dwelling prohibitively expensive. Our only other alternative IMHO would be a space colony.
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ThorTso,

The crater that allegedly wiped out the dinosaurs (lets call it the K-T event) is, if memory serves, 65 miles in diameter. If you assume a radius of 32-1/2 miles, an impactor of that magnitude would very nearly pierce Earth's crust. There is a lot of speculation about whether or not that would cause heavy volcanism from near the crater and provide a major source of ash beyond the initial event. Potentially, you could have the atmosphere obscured for years because of added volcanism. The K-T event is thought to have started fires on a continental scale and caused huge tsunamis worldwide. Some research has indicated that the K-T event might have been multiple impactors; one candidate crater is east of Greenland, I think.

Regardless of unimaginable destruction 65 million years ago, the lowly oppossum survived as did many other critters. I think we can to, provided that we have the means to survive the starvation and wild weather that would follow for several years.

By affordable I mean on the order of $50-150k. Not bad when you consider the cost of other methods.

Scott
 
I am with BAE on this one. A solution has to be designed to a specification. A 75 mile diameter impact crater leaves alot to be desired in detail. Your first objective should be to define a set of assumption around which the project is then engineered.

Just look at what we have so far on this thread. ThorTso and I have a very pesimistic view of the requirements, BAE has a more moderate view and assumes that some meaningful resources may be available, scotjute has some good suggestion but these are built around the premise of a very short term basic shelter against comparatively low levels of energy.

Some of the key things to think about:

1) What kind of terrain is this shelter likely to be located in.
Are you building into solid granite, lose soils, potential flood
conditions, arid terrain, a cave, a mountain top, a cayon?
2) What kind of access and utilities will need to be constructed and
supported?
3) What kinds of forces does this shelter need to withstand? You
mentioned earthquakes, what about temperature variation,
vandalism, electrical & emf, does it need to be water or air
tight?
4) How many people does this solution need to support?
5) How long are they going to be there? Also, what kind of support
is the solution going to provide before and after the event?
6) What are the survival and exit phases and durations?
7) What types of warehousing and tools (material wealth) will the
occupants want to have to face challanges when they leave the
shealter?
8) What kind of budget are you targeting? We may have to give up on
the surround sound indoor theater and gold sink fixures. Given an
unlimited budget I can engineer a way to survive very comfortably.
9) How much maintenance activity are you prepared to do? Do you
want an overengineered system that will seldom break, or a
streamline one that will need periodic repair.

Engineering is about finding a solution that can be applied to solve a problem; you need to start by defining a problem.

n2s
 
Ok, ok - I give. For the sake of argument, here and now only, lets take my own personal design:

1) Western Washington State, rural, on a 20 ft hillside in post ice-age river terraces. 30 acres total property. Sediments are deep, >100 ft, and the water table is ~15 ft below the surface. The aquifer produces ready-to-drink water from a well and is unlikely to drop more than 50 ft in 10 years of drought. Average ground temperature is 45 deg F regardless of season. Soil is suitable for pasture or orchards as is.

2) No outside utilities. This leaves solar-electric (unlikely in the 1st year), wind, and hydro from a river in the back of the property. Frankly, I'm not an electrical engineer, so could use some help in that area.

3) Forces. I am using severe earthquake forces because as I type, the (east-moving) floor of the Pacific is locked up against the bottom of the (west-moving) North American continent. Historically, this subduction zone lets loose every 300 years - the last time was 302 years ago, when the coast dropped ~3 ft in a matter of minutes. Hence the 0.5 g, far worse than earthquake codes require. I want to come through in one piece.

Meteorite imapct force, I think, is pretty binary. With minor variations in survivability around the edges, you either get splatted or you don't. It is too expensive to make another NORAD, so I am just figuring for my "pet" earthquake.

The electrical system will be hardened against EMP from lightning, which is in the GHz range.

4) Occupants: 2 adults + pets with temporary (months) capabilities for 10 more.

5) I am modeling a totally dark show for 12 months. This probably means freezing weather the whole time. After that, the sun should be out enough to raise some crops in a greenhouse at mid 50s temps, say 2000 square feet. Again, botany is not my area and I could use help here. I am assuming a "wierd climate" period of 10 years, which may as well be eternity for design purposes. Basically this means sunlight, but unknown and variable temps, precipitation.

Before the event, it is my house. It should look like a house too, albeit a sheltered one. Picture the south wall exposed and a patio or deck. Concrete can be colored cheaply too, by the way.

6) I'm not sure what you mean by "survival and exit phases and durations".

7) The plan is to stay put for a while, then rebuild life with everyone else. I suppose there might be a period of lawlessness. Occupants will likely have 2000 cubic feet worth of personal storage inside each, more in outbuildings.

8) Budget. I'm figuring $100k for a liveable home, 4500 square feet. (I know, not 3000 sf like I said, but this one is mine.) Liveable to me means warehouse-type floors and dyed concrete counters, not fancy. Fancy can come later, but there will be pictures on the walls and lots of nice plants from the start. This also means I do most of the formwork, etc. If I get hurt and can't do such work, the price may double.

9) Maintenance. Welding, concrete, wood, etc. Basically your typical farm shop. This will be in the above ground garage, which will be the house while the real one is being constructed.

Speak of the devil. I just got an email from a NASA list describing new research about the K-T event. I know everyone wants a more precise definition - this is as specific as I can get:

http://ali.opi.arizona.edu/cgi-bin/...s?ArticleID=5767&wosid=G1Qx2jcSGUlM5fXNis6GWw


EARTH SUFFERED PULSES OF MISERY IN GLOBAL WILDFIRES 65 MILLION YEARS AGO

As an example of how poorly constrained the problem is, the idea of global fires is only a year or so old. Before that the thinking was that everything would freeze. I'm not just being goofy by not constraining the criteria - the criteria really aren't known. If this new research proves well-founded, air filtering/cooling becomes very important.

Scott

PS - maybe a better way to think of my criteria is, "How far can one go with an earth sheltered home? What are the limits of survivability?" It is more about finding limits than setting them.
 
Thanks Scott - that's a bit more concrete :-)

You might consider starting out with something like a set of "threat levels", akin to body armor classifgitions, or how bomb shelter design was done in the 50s, which would allow someone to select how much protection they desire to buy.

For instance, many people might want shelter for city, region, or continent-destroying events, but might view the probability of an Exctinction Event as so low they weren't willing to shell out the money.

Personally, if you can set me up for $100-150k, I'll buy one, and it doesn't have to double as my house.
 
With a water table at ~15 feet, you will run into water trouble. With an 8' ceiling plus being buried 10 feet deep, you will be several feet under water. This will get VERY expensive.

How about this as an alternative...excavate 10 feet down. You will still be well above the water level at this point. Pour your slab foundation, walls and ceiling. I'm assuming that these are all reinforced concrete. Then backfill the dirt that was excavated on top of the structure. You would probably want to buy a used bobcat and sell it when you are done. This amount of excavation could blow your budget very quickly.

Also, have you priced concrete? Run a rough calc on how much you think you will need. Figure $80 per yard and you will see that it adds up very quickly. Are there cheaper alternatives? Can you use I-beams as reinforcement in place of poured concrete? Blocks? Will blocks bear that kind of load? Don't forget to calc the lateral loads on your walls if you use blocks.

Also, will you put furrings and sheetrock on the interior walls or are you going for the austere concrete finish look? If you want to conceal the electrical, the ascetics will get expensive. The cheapest way would be to just route the flex neatly and paint it. It would look like you were living in a Home Depot warehouse but it would work. Do you like stucco?
 
On the food subject:

Storage of food for 4 people for a year shouldn't be too troublesome. A deluxe 1-year supply from <a href="http://www.waltonfeed.com/intro/delux.html">Walton Feed</a> takes 33 cubic feet. Well-stored foods easily have a <a href="http://www.waltonfeed.com/grain/life.html"> 8-10 year shelf-life</a>, so you could just decide to store what you need to live on for the duration, assuming you had the cash to stock up. This might simplify things for you, as you wouldn't have to plan on raising food within the shelter.


A 10-year supply for a family of 4 would take 1320 cubic feet. Not a huge volume at all - a small room would suffice. Keep it relatively dry, and at a cool temperature, and you'll be all set.

You'll need to think about how you're going to cook this stuff though - fuel might become an issue.

On that front, you may be able to harvest quite a bit of wood from your area, even if all the trees have perished...
 
Daniel,

Many tall buildings are built with waterproof foundations, sometimes called raft foundations. These are several stories deep and are often used for parking. The deal is, they displace wet sediment, which is more dense than a building's average density. In other words, the building literally floats. In fact, some old 1950s bomb shelters are popping up out of the ground now due to this buoyancy. The extra mass needed to hold down a building below the water table is one reason for increased cost

Delivered trucks of concrete are $50/yd where I am, or half that if you set up a "batch plant" on site. It's easy to go over the 1000 cubic yard mark if you use a "brute force" approach to various structural problems like the buoyancy thing. My 4500 sq. ft. design is around 750 yards.

Reinforced concrete (R/C) has to have embedded rebar to work right. Sizes are in 8ths of an inch, so #4 bar is 4/8=1/2 in dia. I think I figured one way to reinforce the house with 50,000 linear feet of #4 at a cost of ~$30k. You can use more small bar (smallest is #3) to reduce cracking, as for waterproofness, but that maybe doubles the rebar cost. Fewer large bars are cheaper to a point - splices in #8 have to be welded, and bending them is a problem. (Rebar is almost twice the strength of regular structural steel.) #4 is a good compromise.

Blocks will work fine, but can be more spendy, and cannot be made waterproof by itself. The usual procedure is to run rebar through the wall in a grid pattern, cutting holes in the blocks while you place them, then pump high strength grout through the voids. The amount of rebar depends on the load. R/C requires rebar for lateral loads, too.

I'm a stucco man for interior finish. It can be made to look like anything, smooth to cake icing or highly textured. You can make it out of cement and sand very cheaply.

The walls will most likely be tilt up. I will pour and finish the floor to support a tractor/bobcat. Next, I make a form, say 10x20 ft, in a rectangle on the floor, ~8 in deep. This is just the edge of the wall and any window or door openings. I will then place the rebar and any conduits, suspended in position, and pour the concrete. Finish is usually very good, as one side was on the finished floor (coated w/release) and the other side gets finished by hand . When it gets strong enough I will strip the forms and tilt it up into place. A few connections are made, and voila, a new 20 ft wall section without the need for a concrete pumper, scaffolding, or large crew. Cheap and easy, almost as easy as the floor. The roof is a different story...

About bae's cooking concerns, I have been tring to work up a low temp method to cook rice, but I think you have to cook it at relatively high temps to release the nutrients. Anyone heard or read this?

Scott
 
Electrical systems -

How long do you figure this shelter needs to remain operational?

My experience with batteries (automotive, deep-discharge marine batteries, solar systems) has been that after some number of years, they perish. If your design includes power storage systems that use batteries, you probably need to worry about this. Perhaps some of the telco batteries have longer service lives? Or perhaps you could stock spare batteries w/o electrolyte? Or use some other power storage method (water/generator)?


What all would you like to have power for? What sort of power consumption do you expect?
 
Electrical: Zero.

You could say I have lost most faith in modern electrical gadgets.

I am waiting to see how fuel cell development goes, since this seems to be reliable and might be fueled by easily producible substances, e.g. gasses from compost. Solar panels are the source for now, say 150 W for lights and whatever it takes to run an appropriately sized heat pump to maintain 60 deg F. Like you say, batteries are a problem.

For the moment, I'm not counting on electricity at all and view it as "icing on the cake." A year's supply of propane is less trouble and more reliable. However, I do think that electrical is the most ideal method. I just haven't found any affordable systems that are robust enough.

Lighting is via oil lamps, although that may soon be augmented by LED.

I would like a shelter to be fully functional for a year of dark, freezing weather. This does not include extras like hot running water. Indoor temps shouldn't drop much below 50 deg F, even without heat (due to the geothermal gradient and insulation). Not comfortable, but it won't break pipes or kill you. Passive solar can theoretically raise that to nearly room temperature most of the year in western Washington.

In practice, the total energy bills for sheltered homes are usually 50-75% what equivalent above-ground homes cost. I think this came from The Underground Space Center, in Minnesota, and may use decades-old data.

I have a pretty poor understanding of electricity generation and powered heating. I'm sure others could do substantialy more than this.

Scott
 
Scott,

Why don't you start with an existing design. There must be tens of thousands of old bomb shelter designs around. At least they would have answers for things like water, sewer, and air circulation.

n2s
 
This is an interesting, if unlikely exercise. I have imagined scenarios like this several times. I'm no engineer but here are some thoughts:

I think you might be counting too much on geothermal energy helping to warm you during that critical first year. Back when the "nuclear winter" theme was in full swing I remember reading estimates of temperatures in North America of -100 to -125 degrees F for 8 to 16 months. Unless you are in an area with significant volcanic activity this would likely create a frost line well below your proposed floor. Permafrost in Alaska goes down 45 feet and more.

You may wish to consider the need to have some animals in your menagerie. Game, especially large game is likely to be very scarce if not extinct when you emerge. Animal protein, and especially fat, is going to be a dear commodity. Rabbits, poultry, and perhaps even a small variety of pig may all be worth considering. I'm sure others will have more insight into this. I am not an expert in this area.

Finally, once the worst is over and it becomes possible to scavenge, you should be able to get nearly any non-animal resource you need. If the area where you are is not scorched and utterly devastated there won't be much competition for all the enormous resources left scattered over the landscape by the dying masses.
 
Originally posted by ajrand
I think you might be counting too much on geothermal energy helping to warm you during that critical first year. Back when the "nuclear winter" theme was in full swing I remember reading estimates of temperatures in North America of -100 to -125 degrees F for 8 to 16 months. Unless you are in an area with significant volcanic activity this would likely create a frost line well below your proposed floor. Permafrost in Alaska goes down 45 feet and more.
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My uncle in Ohio has a neat geothermal heating/cooling system. It consists of a deep narrow shaft (hundreds of feet down), through which some fluid is pumped. It uses the Earth as one heat exchanger, and has another up top in the house. The only power it consumes is for the pump. He says his electric bill in the dead of winter runs about $40.

Some concerns with this system:

1) It cost him ~$24k about 5 years ago, so it's outside the proposed budget.

2) It may use more power for the pumps than can reasonably be generated in the scenario.

3) I'm not sure how earthquake-resistant the setup would be. Hate to lose the shaft or some of the deep plumbing.

I think, though that a single year of sub-zero temperatures is unlikely to cool the earth deep down enough to shut down a system like this.
 
Originally posted by ajrand
You may wish to consider the need to have some animals in your menagerie. Game, especially large game is likely to be very scarce if not extinct when you emerge. Animal protein, and especially fat, is going to be a dear commodity. Rabbits, poultry, and perhaps even a small variety of pig may all be worth considering. I'm sure others will have more insight into this. I am not an expert in this area.
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I'd consider stocking nutritional supplements for essential vitamins and amino acids. Raising animals will be quite difficult if the ecosystem has been significantly altered, and you're not going to want to waste your time raising grain/veggies/hay to feed the critters if they can't browse on their own.

Think the Three Sisters - corn, beans, squash. Make sure you pick varieties able to survive in a post-impact scenario.
 
Originally posted by not2sharp
Scott,

Why don't you start with an existing design. There must be tens of thousands of old bomb shelter designs around. At least they would have answers for things like water, sewer, and air circulation.

n2s
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Those things are what I'm getting my engineering degree for! Besides, I want to include more modern construction methods that are stronger and cheaper. My main problems are in non-civil engineering fields, like electrical issues, nutrition, and botany. I can really use the help there.

ajrand,

Geothermal conduction is pretty powerful. It would take many years of those temperatures to jeopardize a well covered earth-sheltered structure. We usually think of all the heat that comes from the sun, and how bad things would be without it. Very true (on the surface), but the net heat flow through Earth's crust is still *out*, not in. At 15-20 ft depth, heat from below is the most important factor for timescales of ~10 years. We owe this to decaying radioactive material in the deep interior of the Earth - our little ball would have long since gone cold without it.

Scott
 
With 75 percent of earths surface under water you better figure
a 75 percent chance of an ocean strike.

Read Lucifer's Hammer by Jerry Pournelle.

If you survive the tsunami your problem is rain or snow, Feet not inches, Biblical stuff.

Ocean strike = a lot of water vapor = a lot of rain or snow.

It could be colder(raised albedo).

It could be hotter(water vapor is a green house gas)

Read the book.;)
 
A water vs land strike is one reason the post-impact conditions are so poorly constrained. Also, the fields of climatological and impact modeling are rapidly developing. I get my atmospheric/geophysical info from journals I take, like the Journal of Geophysical Research, Solid Earth and Planets sections. While the models get better and better, smetimes they disagree with one another quite a bit. It is really scary how little is actually known in science.

Scott
 
Originally posted by Josh Feltman
Hey, beezaur-- are you familiar with Monolithic Domes? Don't know if they are up to a meteor strike or not.
--Josh
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Parking garage floors are sometimes only 3 inches thick - the same thickness reported by these folks. If they are in fact using 6000 psi concrete (almost twice the normal strength) then yes, the things should be as tough as they claim, except possibly for earthquakes.

Their earthquake analysis ( http://www.thedomecompany.com/survivability.html ) is pretty lame - just over the minimum required by law. It may well be that the structures are strong enough, but there are better methods of analysis. I would feel more comfortable seeing some sort of finite element analysis with waves applied from real earthquakes. Really wierd things can happen when you cause a structure to vibrate. Their analysis involves no motion at all and doesn't take into account things that concentrate stress, like corners in doorways or windows.

I believe their claims about strength in high wind. They also claim no serious structural damage would result from flying debris - probably true.

I can't say anything about the thermal claims, but they don't seem unreasonable to me.

I think they probably have a good product. Certainly much stronger and more thermally efficient than a conventional home.

Scott
 
While thinking about a dome shape...have you considered other various shapes? Maybe a concrete A-frame? What would be the pros and cons versus a concrete cube or dome?
 
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