[HN Gopher] Trans-Planetary Subway Systems (1978)
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Trans-Planetary Subway Systems (1978)
Author : simonebrunozzi
Score : 30 points
Date : 2021-04-11 13:34 UTC (9 hours ago)
(HTM) web link (www.rand.org)
(TXT) w3m dump (www.rand.org)
| paulhart wrote:
| More like this:
| https://idlewords.com/2007/04/the_alameda_weehawken_burrito_...
| snurfer wrote:
| Thanks for that link. Tasty visions of things that could-have-
| been...
| divbzero wrote:
| ... instead we got 140 characters.
| briefcomment wrote:
| Is this a giant troll? It's so well done
| MisterBiggs wrote:
| > It will require advanced tunnel-boring machines, such as
| hypersonic projectile spallation, laser beam devices, and the
| "Subterrene" heated tungsten probe that melts through igneous
| rocks.
|
| Sci-fi or research in the 70's?
| dogma1138 wrote:
| Research even before the 70's in the 50's people were looking
| into nuclear powered boring machines that would use heat from
| nuclear fission to melt rocks.
|
| I don't know if this was ever gotten to beyond "cool ideas for
| the nuclear age" concept art pamphlet phase.
| duckfang wrote:
| This seems very similar to Hyperloop, up to the low pressure
| tube, super cheap per ride, intercontinental, and returns energy
| to system.
| ergot_vacation wrote:
| So much so that that one might suspect Hyperloop was almost
| entirely "borrowed" from this idea, which is probably what OP
| meant to suggest. To be fair, the description of Planetran does
| note that the boring itself is the unusually hard part. Maybe
| Elon saw this at some point, figured the boring part was
| finally solvable (which explains why he made such a big deal
| about it), and decided to dust it off.
| geofft wrote:
| Musk mentions RAND's previous work in his paper, but he
| thinks the vacuum requirement is impractical: https://www.tes
| la.com/sites/default/files/blog_images/hyperl...
|
| > _Is there truly a new mode of transport - a fifth mode
| after planes, trains, cars and boats - that meets those
| criteria and is practical to implement? Many ideas for a
| system with most of those properties have been proposed and
| should be acknowledged, reaching as far back as Robert
| Goddard's to proposals in recent decades by the Rand
| Corporation and ET3._
|
| [...]
|
| > _Another extreme is the approach, advocated by Rand and
| ET3, of drawing a hard or near hard vacuum in the tube and
| then using an electromagnetic suspension. The problem with
| this approach is that it is incredibly hard to maintain a
| near vacuum in a room, let alone 700 miles (round trip) of
| large tube with dozens of station gateways and thousands of
| pods entering and exiting every day. All it takes is one
| leaky seal or a small crack somewhere in the hundreds of
| miles of tube and the whole system stops working._
|
| (ET3 is these folks:
| https://en.wikipedia.org/wiki/ET3_Global_Alliance)
| aidenn0 wrote:
| Musk's hyperloop was neither maglev, nor in an evacuated
| tube. It was an air bearing in a reduced (but still fairly
| high) pressure tube.
|
| Apparently the air bearing didn't work out, so all the things
| calling themselves "hyperloop" are maglev and, once you don't
| need the air bearing, it makes sense to lower the pressure as
| much as possible.
| qayxc wrote:
| > It was an air bearing in a reduced (but still fairly
| high) pressure tube.
|
| You are a funny guy :) According to the source [0], the
| pressure was intended to be 100 Pa ("about 1/6 the pressure
| of the atmosphere of Mars").
|
| Technically speaking, this is a fairly good medium vacuum
| [1].
|
| The term "vacuum" itself refers to "a space from which most
| of the air or gas has been removed" [2], so you don't have
| to go into the intergalactic void to achieve it. I think
| ~99.9% qualifies as "most" :D
|
| [0] https://www.tesla.com/sites/default/files/blog_images/h
| yperl... pg. 12
|
| [1] https://en.wikipedia.org/wiki/Vacuum
|
| [2]
| https://dictionary.cambridge.org/dictionary/english/vacuum
| aidenn0 wrote:
| Thanks for the correction. I misremembered it as 1/6 the
| pressure of _Earth 's_ atmosphere which is obviously
| wrong. Yes 100Pa qualifies as "evacuated" by most
| reasonable definitions.
| Taniwha wrote:
| Everything old is new again
| flemhans wrote:
| Let's make it!
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