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The Nightstar Zoo :: View topic - 2017-03-17 Watch your step
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2017-03-17 Watch your step
http://zoo.nightstar.net/viewtopic.php?f=17&t=20875
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Author:  FrankNorman [ Fri Mar 17, 2017 3:06 am ]
Post subject:  2017-03-17 Watch your step

A non-trivial thing about walking around in a spacesuit on the surface of a planet that's at 40 Kelvin - you are super-hot in that environment.
There are a fair number of common compounds, such as Oxygen or Nitrogen, that are solid at that temperature, but will melt or even boil if exposed to heat levels that are still way below that is necessary for life-support?

So how good is the insulation on your spacesuit? Unless you want the landscape to flash-boil at every point you set foot on it, your suit needs to be keeping the heat in, not just the cold out.

Author:  Rombobjörn [ Fri Mar 17, 2017 4:21 am ]
Post subject:  Re: 2017-03-17 Watch your step

Yup. "Keep your heaters running" is quite wrong. Staying warm isn't a problem in space. The problem is getting rid of the heat that you and your equipment produce, as the only way to shed heat in a vacuum is by radiation. Here they may even need to limit their radiation to avoid heating the surface of Bacchus too much.

By the way, "degrees Kelvin" is deprecated since 1968. SI has watts and volts, not "degrees Watt" or "degrees Volta", and temperature is measured in kelvins, not "degrees Kelvin".

Author:  FreeFlier [ Fri Mar 17, 2017 8:40 am ]
Post subject:  Re: 2017-03-17 Watch your step

If they're leaking enough heat to melt or worse evaporate volatiles, heat loss will become a big big problem very very rapidly.

They're going to be operating on a cryogenic planetary surface, not in free space. There should be an atmosphere of some sort, no matter how thin. AFAIK, even the moon has an atmosphere.

--FreeFlier

Author:  Rombobjörn [ Fri Mar 17, 2017 11:20 am ]
Post subject:  Re: 2017-03-17 Watch your step

Image

An atmosphere of hydrogen and helium should be possible. At 1.6 g₀ the escape velocity seems to be high enough to retain even hydrogen when it's as cold as 40 kelvins. No other gasses will contribute noticeably at that temperature. The vapor pressure of nitrogen at 40 kelvins is about 10 pascals. That's less than 1/10000 atmosphere.

Author:  grahamf [ Fri Mar 17, 2017 8:11 pm ]
Post subject:  Re: 2017-03-17 Watch your step

So, seems that:

1. They are radiating enough heat to evaporate the ground.

2. Their heaters are not powerful enough to keep them from feeling chilly, but sufficient enough to keep them from flash-freezing (for now)

Author:  palu [ Fri Mar 17, 2017 8:38 pm ]
Post subject:  Re: 2017-03-17 Watch your step

Why don't they just fly above the surface?

Author:  Black Sheep [ Fri Mar 17, 2017 9:04 pm ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  FreeFlier [ Sat Mar 18, 2017 1:26 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  evileeyore [ Sat Mar 18, 2017 1:35 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  Warior4356 [ Sat Mar 18, 2017 9:45 pm ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  richv [ Sun Mar 19, 2017 3:05 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  ExenTrik [ Sun Mar 19, 2017 4:52 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  rleggett [ Sun Mar 19, 2017 1:54 pm ]
Post subject:  Re: 2017-03-17 Watch your step

There was scene in classic science fiction - either Haldeman's Forever War, or Heinlein's Starship Troopers - where a drill sergeant explains why you have to keep the powered armor's radiator, mounted on the back, from hitting Pluto's ice.

Basically it turns you into a rocket and kills you.

Author:  FreeFlier [ Sun Mar 19, 2017 6:00 pm ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  ExenTrik [ Mon Mar 20, 2017 1:03 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  FreeFlier [ Mon Mar 20, 2017 8:25 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  Barmaglot [ Mon Mar 20, 2017 11:34 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  grahamf [ Mon Mar 20, 2017 6:13 pm ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  ExenTrik [ Tue Mar 21, 2017 12:10 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  FreeFlier [ Tue Mar 21, 2017 8:15 am ]
Post subject:  Re: 2017-03-17 Watch your step


Author:  StClair [ Wed Mar 22, 2017 6:51 am ]
Post subject:  Re: 2017-03-17 Watch your step

I remember the incident from Forever War, and also another story from my youth, where a Plutonian explorer has a trip-and-fall and punctures one of their air tanks - which is bad not because they're in (immediate) danger of asphyxiating, but because the escaping gas flash-freezes them to the terrain. Fortunately, someone happens along who can melt the "ice" and free them...

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