[HN Gopher] The Human Body in Space: Distinguishing Fact from Fi...
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The Human Body in Space: Distinguishing Fact from Fiction (2013)
Author : jacksonkmarley
Score : 60 points
Date : 2021-06-02 12:10 UTC (1 days ago)
(HTM) web link (sitn.hms.harvard.edu)
(TXT) w3m dump (sitn.hms.harvard.edu)
| tgb wrote:
| > Because thermal radiation (the heat of the stove that you can
| feel from a distance, or from the Sun's rays) becomes the
| predominant process for heat transfer, one might feel slightly
| warm if directly exposed to the Sun's radiation, or slightly cool
| if shaded from sunlight, where the person's own body will radiate
| away heat.
|
| Since the body also produces heat, would you even feel cool when
| shaded? If body heat generation outpaces radiation then I think
| you'd feel warm. Wikipedia puts the energy radiated out as about
| 2000kcals per day, or right around a human would produce from
| metabolism. So I guess it basically balances out.
|
| https://en.wikipedia.org/wiki/Black-body_radiation#Human-bod...
| geranim0 wrote:
| In the movie Men Behind the Sun they show the japanse putting
| people in vacuum chambers and literally shit their guts
| sammalloy wrote:
| This article is from 2013, but since 2019, there's been active
| research in things like latent herpes reactivation, which could
| have implications for long duration spaceflight.
|
| https://www.frontiersin.org/articles/10.3389/fmicb.2019.0001...
| zeeshanqureshi wrote:
| Plus there could also be the psychological effects of possibly
| being isolated and confined in a small floating tin can.
| Akinato wrote:
| IIRC Nasa put out a bunch of RFPs last year for studying,
| identifying, and alleviating that exact problem.
| seaorg wrote:
| Imagine if they tried to cram a bunch of people in a literal
| metal tube with no windows and send them to the bottom of the
| ocean for months as a time. How could anyone be stupid enough
| to think that would work?
| mattowen_uk wrote:
| Reading this, I learned that the 'Exposed To Space' stuff that
| happens in The Expanse (TV show - I've not read the books) is
| pretty much spot on.
| causality0 wrote:
| _since two of the three methods of heat transfer (conduction and
| convection)_
|
| This always drives me nuts. Convection _is_ conduction, just in a
| fluid. Conduction and radiation are two entirely different
| physical processes.
| guntars wrote:
| I think the distinguishing difference between conduction in a
| fluid and convection is that the fluid "leaves" and takes away
| the heat.
| lmilcin wrote:
| Well, not exactly.
|
| Conduction means you touch something and that something slowly
| gets hotter and conducts heat away from your body. You can
| calculate how fast the energy is transferred based on
| properties of the material and geometry of objects and their
| interface.
|
| Convection means you touch something and that something is
| constantly being replaced. You can't use the formula for
| conduction here.
|
| In case of convection, the basic mechanism of energy being
| moved has nothing to do with conduction, rather with movement
| (replacement) of the material that takes away the heat.
|
| How is moving heat by moving the material and moving heat by
| letting it to dissipate through stationary material not two
| different processes?
| only_as_i_fall wrote:
| Actually conduction is radiation at the atomic level. If you
| bring either point up in a conversation which is understood to
| be about macroscopic physics though you're really just being an
| ass.
| causality0 wrote:
| Thermal conduction is carried out with phonons and free
| electrons. It has a finite range. It is fundamentally
| distinct from thermal radiation which is propagated by
| photons with an infinite range.
| swiley wrote:
| I thought conduction propagated as phonons rather than
| photons.
|
| But I guess the particle interaction comes from photon
| exchange, on the other hand the frequencies are different
| enough I think you can safely call it a different thing (like
| how UV and AM radio are different.)
| zizee wrote:
| Doesn't convection also require movement of the fluid? Under
| gravity convection works by changes in density when the fluid
| is heated (e.g. hot air rises). This movement of the fluid
| provides an extra component beyond regular conduction. The
| movement of the fluid transfers heat away.
|
| In low g environments, convection due to density changes
| doesn't happen (hot air does not rise) which means heat pools
| around bodies at rest.
|
| Edit: after reading the article a bit, i see that you were
| quoting a section that ends with "...(conduction and
| convection) cannot occur without matter." Which does make the
| distinction the author was making a little more less useful.
| However lack of convection is an issue inside the space station
| where fans must be installed to keep air from pooling around
| heat sources like lights and human bodies.
| seaorg wrote:
| Make the transit ship spin. Surround the habitable parts with
| water and other materials. It's so simple but nobody seems to be
| aware that these are solved problems.
| jccalhoun wrote:
| Lots of people have thought of similar things. I know I have
| read scifi which uses water for shielding but I can't think of
| a specific name.
|
| However, water isn't light. According to this post on stack
| exchange it would take something like 330,000kg of water to
| shield a crew. Getting that into orbit is a big task.
| Supermancho wrote:
| > It's so simple but nobody seems to be aware that these are
| solved problems.
|
| It isnt reasonable to assume napkin solutions are "so simple"
| in practice or have not been considered. There are plenty of
| people smarter than either of us that look at these problems.
| seaorg wrote:
| The problem isn't the smart people who look at these
| problems. It's the collective behavior of the masses to have
| amnesia about basic physics.
| localhost wrote:
| I just finished listening to the Audible narration of the
| excellent Project Hail Mary [1] book by Andy Weir. It explores
| quite a few of these issues, including the cosmic radiation one.
| Highly recommended!
|
| [1] https://www.andyweirauthor.com/books/project-hail-mary
| Zimahl wrote:
| The Expanse handles this stuff much better than other shows, as
| has been noted many times. As entertaining as it is, For All
| Mankind gets things very wrong in a lot of cases and falls prey
| to a lot of the 'space tropes' that plague sci-fi. And I
| certainly don't expect hard sci-fi realism everywhere, but in
| something like For All Mankind, which is supposed to exist in an
| alternate timeline but be firmly planted in the real world, it's
| jarring. When it's in something like the movie Event Horizon I
| really don't care about realism.
| at_a_remove wrote:
| What you really want is something like the Sturm Invocation
| from Charles Sheffield.
| nojokes wrote:
| In one episode Naomi inhales in just before exposure to the
| vacuum - it would have been fatal according to the article.
| herewulf wrote:
| If you're referring to the scene where she deliberately exits
| an airlock, then she actually exhaled whereas the other
| person with her did not and died.
|
| (Purposely being vague to avoiding spoiling anyone on this
| great series)
| nojokes wrote:
| Yes, that one.
|
| I rewatched this moment on Prime and I remembered it
| correctly. While she exhales after last words slowly, she
| inhales sharply before pressing the button.
|
| I remember it probably because I watch everything with
| subtitles on and that was written. I now watched it without
| to avoid being biased and it still holds.
|
| In addition she was exposed to the vacuum about 40 seconds
| before using the shot.
| meristem wrote:
| In the book she exhales: "She pushed her jaw forward in a
| yawn, opening her throat and her Eustachian tubes. Cyn yelped
| as she hit OPEN OUTER DOOR. Air tugged at her once, hard, as
| it evacuated. Adrenaline flooded her blood as she was
| assaulted invisibly on every square centimeter of flesh. The
| breath in her lungs rushed out of her, trying to pull her
| lungs along with it.[...] With her lungs empty, there was no
| reserve. She wasn't holding her breath, surviving off the gas
| held inside her. Someone could hold their breath for a couple
| minutes. In the vacuum, she could make it maybe fifteen
| seconds unaided.
|
| Corey, James S.A.. Nemesis Games (The Expanse) (p. 425).
| Orbit. Kindle Edition.
| nojokes wrote:
| Nice to know that the author got it right in the book.
| herewulf wrote:
| This should be tagged 2013.
|
| I came here just now thinking it was a new article. I actually
| found it by way of Google a couple months ago after watching a
| certain episode of The Expanse.
| [deleted]
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