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Author Topic: Could you urinate on the moon?  (Read 3004 times)

Offline knebulos

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Could you urinate on the moon?
« on: 15/10/2015 22:34:10 »
So A friend and I have been having a serious discussion about urinating on to the lunar surface.
Aside from the low external pressure causing "the weirdest boner" the discussion of temperature came up. She recons you'd have a brief window of time as the sun comes over the horizon before it gets too hot. I think that because there is no atmosphere to gradually heat up it would be more of a binary; in the sun/in the shade very hot/very cold.

(unless you pressed your member against the surface so it could heat up gradually through thermal conduction as the surface around your shadow gets hot) what to you lot think?

Also seeing as the higher bands of ultra violet light aren't being filtered, can you get a melanoma on the glans of your penis?

(actually I don't know whether to post this in the physics boards or physiology).
« Last Edit: 15/10/2015 23:21:09 by chris »


 
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Offline alancalverd

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Re: Urinating on the moon.
« Reply #1 on: 15/10/2015 22:58:10 »
A pee tube is built into any pressure suit intended for long-term wear. Short-term you use a nappy (diaper).

Glider pilots suffer from cold: a flight of more than 3 hours becomes a test of bladder control and moral fibre as much as airmanship. So some gliders have a venturi waste tube attached to a rubber cup (known in less PC days as the "Polish microphone" - well, it was invented in Poland) but a fighter test pilot, accustomed to having proper personal plumbing in his office suit, attached himself to a glider venturi with a transparent polythene bag. The other thing glider pilots suffer is sunburn. The experiment was well publicised in the 1970s and I don't think has been repeated.
 
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Offline Colin2B

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Re: Urinating on the moon.
« Reply #2 on: 15/10/2015 23:12:39 »
..., can you get a melanoma on the gland of your penis?
I think this is the least of your worries. Depending on timing you would either pee steam or ice, but the pressure differential would ensure that, whichever it was, a considerable part of your insides would follow down that rather small tube.
Don't try this at home children.
 
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Offline Bored chemist

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Re: Could you urinate on the moon?
« Reply #3 on: 18/10/2015 18:20:23 »
They don't put any more gas in space suits than they need to, because inflating them makes them difficult to band.
So they are often run at about 0.2 atmospheres pressure of oxygen (and without any nitrogen).
So the pressure difference between the inside and the outside of the suit is about 150 mmHg.
It's possible to have blood pressure that high
https://en.wikipedia.org/wiki/Hypertension
and survive without all your bits bursting.
In fact, if you are 2 metres tall (that's near the upper range for people but not impossible) the difference in pressure between you head and your feet is in the same ballpark as the pressure they inflate space suits to.

So, it's just about possible that you could get by with a pee tube.
However, it still seems to me to be one of the few circumstances where a nappy would look like a good idea.
 
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Offline Bored chemist

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Offline evan_au

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Re: Could you urinate on the moon?
« Reply #5 on: 18/10/2015 21:50:05 »
Given that water is a pretty scarce resource over most of the Moon, peeing into the Solar wind would be a bad move for anyone planning a long-term stay.
 
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Offline chris

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Re: Could you urinate on the moon?
« Reply #6 on: 18/10/2015 23:42:14 »
Wonderful question with wonderful answers that made me chuckle!
 

Offline Colin2B

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Re: Could you urinate on the moon?
« Reply #7 on: 19/10/2015 08:49:27 »
... they are often run at about 0.2 atmospheres pressure of oxygen (and without any nitrogen).
So the pressure difference between the inside and the outside of the suit is about 150 mmHg.
It's possible to have blood pressure that high
I might have over egged the effect, but it would still be quite an experience.
I once gave first aid to someone who had cut an artery, the blood had sprayed over a considerable area and I'm sure it would have been spectacular in a vacuum.

Anyone who saw 2001 knows you can survive a vacuum for short periods, but the description you provided hints at a more interesting effect.
Water in vacuum will boil at room temp, so will the urine in the urethra. But the heat of vaporisation has to come from somewhere and so it will quickly freeze, this is likely to cause a solid plug of ice down the urethra.
I believe the technical term for this is a hard in.  [:0]


 

Offline evan_au

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Re: Could you urinate on the moon?
« Reply #8 on: 19/10/2015 18:01:15 »
I don't know how well plants will grow in crushed carbonaceous chondrites, but it seems that it will be important to recycle urea as a source of nitrogen, for building into edible protein.

Of course, maintaining good lighting and good insulation during the 2-week-long nights will also be vital for crop growth on the Moon.
 

Offline Bored chemist

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Re: Could you urinate on the moon?
« Reply #9 on: 19/10/2015 19:49:11 »
I think that even sea plants would find urine too salty.

If the flow of urine is fast enough it might manage to get out before boiling and or freezing.
There still does not seem to be a positive side to this.
 

Offline Colin2B

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Re: Could you urinate on the moon?
« Reply #10 on: 20/10/2015 16:17:19 »
There still does not seem to be a positive side to this.
Well it has provoked some interesting thoughts.

I have heard that Dr Johnson (no pun intended) said that no man should pass up an opportunity to pass water, true or not I dont know, but even on the moon ....
However, I am reminded of the constant cry of parents - why didn't you go before we left home?
 

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Re: Could you urinate on the moon?
« Reply #10 on: 20/10/2015 16:17:19 »

 

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