BenBurch
Gatekeeper of The Left
I still believe I could engineer a railway to the top. Weather is just a parameter.
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What if Earth had a 12,000+ meter mountain range?
roger
Penultimate Amazing
- Joined
- May 22, 2002
- Messages
- 11,466
No going out of my way - that is the weather we already have on our current peaks - where we have no telescopes. I'm being generous. The climbing period on Mt. Everest is very short - a few weeks in May, a few more weeks in fall. That's it. Otherwise, even with the very best equipment, humans cannot survive there. By "survive" I mean live 24 hours. One of the greatest human feats was Messner climbing Everest in the wintertime - I don't foresee that happening again anytime soon, and certainly not with another 4000m tacked on for good measure. I'm thinking there is a reason, when they put up a scope in the Himalayas, that they chose the low foothills over the tall peaks. I'm also thinking there is a reason that various observatory sites that I googled tout things like the easy access via roads, good weather, etc.
I have no problem with having fun imagining stuff, but you have to stay in this world. Your $500M tunnel requires people to work in space suits, for one tiny example. It's something we've never done before. Then you'd have to build the facilities in one of the most hostile locations on the planet. Erecting a large telescope requires large trucks to level the ground, the pouring of concrete, cranes to position multi-ton equipment. You are in temperatures where computers fail. Sorry, my friends have carried too many dead people off these mountains, and my grandfather worked too long on high altitude and extreme weather engineering for the Air Force for me (and I've participated in high altitude rescues (and been rescued) as well) to take the idea of a crew traipsing off to perform probably the biggest engineering job the human race ever attempted for the price of a tunnel that was dug under a river seriously. The strongest, most atheletic men and women in the world, with the best equipment available, scamper up and down through very slim breaks in the weather, and pay with their lives if the weather shifts a bit, a piece of equipment malfunctions, or their body isn't quite up the the task. The average human can't even walk up there, it is so difficult (I'm not kidding, the hardest thing I've ever done in my life was walk on a gentle slope at altitude - I ended up crawling and having to be carried). But somehow we are going to do major construction, at 4000m higher, for a fraction of the cost of the Big Dig? Okay, why not? Easy peasy.
eta: point of reference - the following may allow you to survive at 8000m, if you are very strong, and the weather is unusually fine, for a 24 hour period. Those conditions exist for a few days over a few week period in the spring, and then in the fall. This equipment is extremely inadequate for the 12km peak - you need more insulation for cold, you need far better oxygen, and of course that suit would be destroyed by any attempt at construction. If the weather is less than perfect, well, you literally freeze to death wearing this. Or, if you are out there a little too long, you go blind from the uv. Or your mask gets frosted over, you take it off to clear it, and your face flash freezes. Etc. So many ways to die. So few ways to survive.
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Quite the opposite; I said, it's a shirtsleeve environment because temperature- and oxygen-controlled air is supplied by the mine ventilation system, which is already true of ordinary mines. You only need a space suit if you want to exit the final plenum that leads from the mine's 50/50 O2/N2 to the outside 20/80 O2/N2. So you engineer things so that no one (or nearly so) has to do that.
That's the cheapest way to erect a large telescope. That's obviously what you do when your site has road access---you do the cheap thing.
At the top of this mineshaft, they'll probably find a more expensive, less-assembly-required way to do it. For example, you might have the thing assembled intact in the safety of the mine, in a shaft below a pad-less and unimproved mountaintop with a rough hole in it. For operations, the crew retreats, some sort of plenum retracts, and a hydraulic ram lifts the telescope into viewing position.
You know what's a really, really expensive way to erect a large telescope? Beefing it up so it survives 6 gee acceleration and 10 gee vibration, then strapping it to a half-million pounds of aluminum and ammonium perchlorate, setting it on fire, and launching it into an orbit that cycles between 300K sunlight and 150K nighttime every 90 minutes. There are lots of things to object to about this, including "how do you pour a concrete pad in space" and "an astronaut can't survive out there for more than 60 seconds". How do you build a telescope that can do this? By treating it as an engineering problem, figuring out what the hard parts are, and designing solutions. Ditto for ALMA, SOFIA, Dome C, etc.
No they don't. Satellites and scientific balloons have been running electronics in colder environments for the better half of a century.
Nobody's scampering anywhere. Nobody is asking Reinhold Messner to strap on an oxygen tank and pour concrete at 12,000m. This is not a mountaineering issue, it's an engineering issue. The concrete-pouring and rail-laying is done by miners in a nice warm mineshaft wearing mining suits and breathing mine air. Without a pressure gauge they can't tell what altitude they're at, because they're breathing sea-level-like oxygen. During the mining process, there's a (brief) transition between "a blind tunnel which ends near the mountaintop" and "tunnel whose final section is exposed and unsurvivable" and "a tunnel with a door at the end", and there must be an engineering solution to that transition.
The cost of the Big Dig has virtually nothing to do with the cost of tunnelling. That cost came from the delicate tangle of the new construction amid existing surface roads, utilities, railways, etc.
BenBurch
Gatekeeper of The Left
A shaft built upwards still loses pressure as it rises.
Similarly, a deep mine is at a higher pressure than sea level.
You can maintain pressure, but you will need air locks.
Similarly, a deep mine is at a higher pressure than sea level.
You can maintain pressure, but you will need air locks.
Yes, but you don't need to maintain sea-level pressure. You just need to maintain sea level oxygen partial pressure. This can be done by dividing up the mine airspace, but the dividing walls don't need to be pressure-tight---heck, they only need to be leaktight in the gross sense.
Let's give a concrete example. You enter the mine at 1600m, into a shaft filled with ambient air. That's 860mbar total, and it's a mix of 172 mbar O2 in 688 mbar nitrogen. You take the elevator up to 2600m, where the air has thinned to 760 mbar (152 O2 + 608 N2) which means you're a bit short of breath. Then you step through a plenum---via a cheap "airlock" with two plastic doors---and on the other side the air is 172 mbar O2, just like it was at the entrance. The difference on this side is that it's 172mbar O2 in 588 mbar N2---i.e. it's enriched to 22.6%---so that the total pressure is 760, and there's no pressure drop across the plenum.
You continue elevating to 3500m, where the pressure has dropped to 650. There, a plenum allows you to pass from low-enriched (150mbar O2, a bit thin) to higher-enriched (26.5%, so 172mbar O2 in 480mbar N2) and you're again breathing all the oxygen you need.
After seven or eight plenums, you're into 50-50 O2/N2, which you breathe normally at ambient *pressure* at mountaintop altitudes.
The nice thing about ambient pressure is that you don't need to be leaktight. What happens if there's a crack the rock wall? A grommet hole in a plenum? Someone mishandles the airlock doors? Nothing, it just lets some gas exchange by diffusion---it doesn't squirt out under pressure like air out of a latex balloon.
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BenBurch
Gatekeeper of The Left
Got it. Makes sense.
BenBurch
Gatekeeper of The Left
Humans have almost as much imperative to build as Doozers.
Diffusion-rate depends on partial pressure.
One would have to breath pure oxygen because the pressure is about 20% of sealevel. The partial pressure of oxygen at sealevel is 21%.
¡No!
The pressure on Mars is less than 1% the sealevel pressure on Earth. If he call it an whole 1% of sealevelpressure on Earth, pure oxygen at that pressure would diffuse at 1/20th the rate it does at sealevel on Earth. Also, water at bloodtemparature boils at that pressure, so human blood would boil on Mars.
Technically, a vacuum has no temperature (not 0 Kelvin, but inapplicable) because a vacuum is nothing, but with boiling blood and lack of oxygen, an human in a vacuum will loose consciousness in 10 to 20 seconds and die in less than a minute. One does need a spacesuit in Space.
One would have to breath pure oxygen because the pressure is about 20% of sealevel. The partial pressure of oxygen at sealevel is 21%.
¡No!
The pressure on Mars is less than 1% the sealevel pressure on Earth. If he call it an whole 1% of sealevelpressure on Earth, pure oxygen at that pressure would diffuse at 1/20th the rate it does at sealevel on Earth. Also, water at bloodtemparature boils at that pressure, so human blood would boil on Mars.
Technically, a vacuum has no temperature (not 0 Kelvin, but inapplicable) because a vacuum is nothing, but with boiling blood and lack of oxygen, an human in a vacuum will loose consciousness in 10 to 20 seconds and die in less than a minute. One does need a spacesuit in Space.