Shirtsleeves on Mars? - Page 3 - Orbiter-Forum

RGClark · 07-15-2012, 10:25 PM

Quote:

Originally Posted by T.Neo

Fun fact: only relatively minor environmental alteration would be required on Mars to allow humans to survive outside unaided, provided they had access to breathing equipment, and proper clothing (depending on the weather).

By the readings of the Mars Pathfinder mission the temperature drops rapidly as you rise above the surface because of the thin atmosphere. From my recollection it got below freezing just 5 feet above the surface even if the surface temperature was at 20 degrees C.
So you'd have to wear heavy clothing even on the "warmest" days.

Bob Clark

N_Molson · 07-15-2012, 11:05 PM

And still, the average temperature on the planet is -60° to -70°C... To be compared with Earth +14°C.

If I had to make a ranking of the "less hostile places for the human body in the solar system" it would be something like :

1) Earth
2) Mars
3) Titan
4) Solid bodies without significant atmosphere but with significant gravity (Moon, Pluto...)
5) Space
6, 7) Mercury or Venus (I can't decide which is worse !)
...
end-1) : Gaseous giants
end) : Sun

Not sure about 4 and 5, because of possible thermic conduction.

SpaceNut · 07-15-2012, 11:45 PM

Speaking of gruesome imagery... I read this story about a small miltary reactor the SL-1 reactor, which, had a stuck control rod. A guy went down to break it free, and, in the process, pulled control rod out WAY too far, causing the reaactor to overload, and exploded vertically, impaling the guy to the ceiling.

The radiation was so bad that small groups of 1 or 2 men would run in, do 1 or 2 minutes worth of work, then run out because the radiation was so bad. It was exactly this accident which caused the NRC to make the rule that it has to be impossible to withdraw a control rod beyond a certain point to prevent any such thing ever happening again.

To drag back topic though, you're nuts if you think you could expose one's self the 100 times less atmospheric pressure than the earth and think you'd last more than seconds...

Also, the one place I don't think has been mention is Venus... not the surface, but about 50km up is really close in temp AND pressure, hence, would make my list of non-Terran spots to poke your head out the window unaided.

T.Neo · 07-15-2012, 11:54 PM

Quote:

By the readings of the Mars Pathfinder mission the temperature drops rapidly as you rise above the surface because of the thin atmosphere. From my recollection it got below freezing just 5 feet above the surface even if the surface temperature was at 20 degrees C.
So you'd have to wear heavy clothing even on the "warmest" days.

The greenhouse effect of a thicker atmosphere must also be taken into account. A 150 millibar atmosphere probably won't make Mars a tropical paradise any time soon, but it could warm the planet considerably. Thicker air will also cause greater conduction of heat away from people, though.

Quote:

If I had to make a ranking of the "less hostile places for the human body in the solar system" it would be something like :

I would not rank Titan very highly at all. It may have a surface atmospheric pressure comparable to Earth at its surface, but the atmosphere is frigid and toxic. We don't have any data of exposure of humans to Titan-like conditions, but with a medium to suck heat from the body, an unprotected human would probably be worse off there than they would in a vacuum. This is also a concern to anyone wanting to build a Titan-suit or similar protective gear.

The most earthlike place elsewhere in the solar system is probably the upper atmosphere of Venus, where the pressure is roughly 1 bar and the temperature ranges from between 0-50 degrees. You could survive there with breathing equipment, but you'd also need protection against sulphuric acid...

EDIT: Beaten by SpaceNut.

SpaceNut · 07-16-2012, 12:44 AM

Well T.Neo... oddly enough, I got interested in Venus a bit just the other day and was reading about it, and I've read before, honestly, I think based on an add on for Orbiter, about the sweet conditions in the upper atmosphere. I've also seen some videos that show planes and balloons that could exist there as well.

**Quick_Nick** · 07-16-2012, 03:08 AM

Venus Station

Shukra_Venus_Station_080813

SpaceNut · 07-16-2012, 03:25 AM

Quote:

Originally Posted by Quick_Nick

Venus Station
Shukra_Venus_Station_080813

Yep, that's it... cool add on, and THAT's where I want to be if I'm stickin' my head out the window ... depending on how bad the acid is that is

Andy44 · 07-16-2012, 03:41 AM

Quote:

Originally Posted by SpaceNut

Speaking of gruesome imagery... I read this story about a small miltary reactor the SL-1 reactor,

SL-1 The Accident: Phases I and II - YouTube

Back on topic: Artlav's cartoon reminded me of something else: Lung expansion injury.

If you've had SCUBA dive training you'll be familiar with this. In the event you are at depth breathing compressed air and suddenly have to surface in an emergency, the very last thing you want to do is hold your breath! If you are at say, 30m (99ft) of depth then the air you are breathing from your regulator is at 4 atmospheres of pressure. Hold a lungful of that inside you and swim fast to the surface and your lungs will try to expand until that air is at four times the volume, causing painful and deadly damage to your lungs.

So, if you step out of an airlock on Mars wearing only a coat and an oxygen mask, the oxygen in your lungs will try to blow outwards until the pressure is equal to the ambient pressure. As a result, there may not be enough left in your lungs to keep you conscious.

Remember, U2 air crews must wear pressure suits; a mere O2 mask is not enough.

**Urwumpe** · 07-16-2012, 06:22 AM

Quote:

Originally Posted by TMac3000

The air is thin enough that I'm pretty sure your blood would boil.

Your blood can't boil. luckily for your health, your blood vessels are pressurized and can tolerate even vacuum.

But on Mars, the pressure would be too low to transfer oxygen into your blood or from the blood to your cells that need it. Without a pressure suit (no full spacesuit though), you would simply asphyxiate. Just a breathing mask wouldn't work.

The atmosphere on Mars is equivalent to Earths atmosphere in 50 km altitude... almost space.

TMac3000 · 07-17-2012, 12:03 AM

Point taken

But I think we're all pretty much agreed that shirt sleeves on Mars would be a bad idea

**Urwumpe** · 07-17-2012, 05:53 AM

Quote:

Originally Posted by asbjos

Sudden depressurization has happened under spaceflight. This was exactly what happened during Soyuz 11. A valve opened short before re-entry, and the crew got killed by the low pressure

Wasn't exactly sudden, since it took 90 seconds until the pressure dropped below the limits for humans to stay awake.

The Challenger accident was likely the only true explosive decompression in spaceflight, since the destruction of the spacecraft and the primary structure of the cabin resulted in a sudden loss of pressure to the near vacuum at 25 km altitude.

07-15-2012, 11:45 PM	#33
SpaceNut Orbinaut	Speaking of gruesome imagery... I read this story about a small miltary reactor the SL-1 reactor, which, had a stuck control rod. A guy went down to break it free, and, in the process, pulled control rod out WAY too far, causing the reaactor to overload, and exploded vertically, impaling the guy to the ceiling. The radiation was so bad that small groups of 1 or 2 men would run in, do 1 or 2 minutes worth of work, then run out because the radiation was so bad. It was exactly this accident which caused the NRC to make the rule that it has to be impossible to withdraw a control rod beyond a certain point to prevent any such thing ever happening again. To drag back topic though, you're nuts if you think you could expose one's self the 100 times less atmospheric pressure than the earth and think you'd last more than seconds... Also, the one place I don't think has been mention is Venus... not the surface, but about 50km up is really close in temp AND pressure, hence, would make my list of non-Terran spots to poke your head out the window unaided. Last edited by SpaceNut; 07-15-2012 at 11:53 PM.

07-15-2012, 11:54 PM	#34
T.Neo SA 2010 Soccermaniac	Quote: By the readings of the Mars Pathfinder mission the temperature drops rapidly as you rise above the surface because of the thin atmosphere. From my recollection it got below freezing just 5 feet above the surface even if the surface temperature was at 20 degrees C. So you'd have to wear heavy clothing even on the "warmest" days. The greenhouse effect of a thicker atmosphere must also be taken into account. A 150 millibar atmosphere probably won't make Mars a tropical paradise any time soon, but it could warm the planet considerably. Thicker air will also cause greater conduction of heat away from people, though. Quote: If I had to make a ranking of the "less hostile places for the human body in the solar system" it would be something like : I would not rank Titan very highly at all. It may have a surface atmospheric pressure comparable to Earth at its surface, but the atmosphere is frigid and toxic. We don't have any data of exposure of humans to Titan-like conditions, but with a medium to suck heat from the body, an unprotected human would probably be worse off there than they would in a vacuum. This is also a concern to anyone wanting to build a Titan-suit or similar protective gear. The most earthlike place elsewhere in the solar system is probably the upper atmosphere of Venus, where the pressure is roughly 1 bar and the temperature ranges from between 0-50 degrees. You could survive there with breathing equipment, but you'd also need protection against sulphuric acid... EDIT: Beaten by SpaceNut. Last edited by T.Neo; 07-15-2012 at 11:59 PM.

07-16-2012, 03:08 AM	#36
Quick_Nick Passed the Turing Test	Venus Station Shukra_Venus_Station_080813 Shukra_Venus_Station_080813

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07-15-2012, 10:25 PM	#31
RGClark Mathematician	Quote: Originally Posted by T.Neo Fun fact: only relatively minor environmental alteration would be required on Mars to allow humans to survive outside unaided, provided they had access to breathing equipment, and proper clothing (depending on the weather). By the readings of the Mars Pathfinder mission the temperature drops rapidly as you rise above the surface because of the thin atmosphere. From my recollection it got below freezing just 5 feet above the surface even if the surface temperature was at 20 degrees C. So you'd have to wear heavy clothing even on the "warmest" days. Bob Clark

07-15-2012, 11:05 PM	#32
N_Molson Addon Developer	And still, the average temperature on the planet is -60° to -70°C... To be compared with Earth +14°C. If I had to make a ranking of the "less hostile places for the human body in the solar system" it would be something like : 1) Earth 2) Mars 3) Titan 4) Solid bodies without significant atmosphere but with significant gravity (Moon, Pluto...) 5) Space 6, 7) Mercury or Venus (I can't decide which is worse !) ... end-1) : Gaseous giants end) : Sun Not sure about 4 and 5, because of possible thermic conduction.

07-16-2012, 12:44 AM	#35
SpaceNut Orbinaut	Well T.Neo... oddly enough, I got interested in Venus a bit just the other day and was reading about it, and I've read before, honestly, I think based on an add on for Orbiter, about the sweet conditions in the upper atmosphere. I've also seen some videos that show planes and balloons that could exist there as well.

07-16-2012, 03:25 AM	#37
SpaceNut Orbinaut	Quote: Originally Posted by Quick_Nick Venus Station Shukra_Venus_Station_080813 Yep, that's it... cool add on, and THAT's where I want to be if I'm stickin' my head out the window ... depending on how bad the acid is that is

07-16-2012, 06:22 AM	#39
Urwumpe Donator	Quote: Originally Posted by TMac3000 The air is thin enough that I'm pretty sure your blood would boil. Your blood can't boil. luckily for your health, your blood vessels are pressurized and can tolerate even vacuum. But on Mars, the pressure would be too low to transfer oxygen into your blood or from the blood to your cells that need it. Without a pressure suit (no full spacesuit though), you would simply asphyxiate. Just a breathing mask wouldn't work. The atmosphere on Mars is equivalent to Earths atmosphere in 50 km altitude... almost space.

07-17-2012, 12:03 AM	#40
TMac3000 CEO and Founder: Real Time Inc	Point taken But I think we're all pretty much agreed that shirt sleeves on Mars would be a bad idea

07-17-2012, 05:53 AM	#41
Urwumpe Donator	Quote: Originally Posted by asbjos Sudden depressurization has happened under spaceflight. This was exactly what happened during Soyuz 11. A valve opened short before re-entry, and the crew got killed by the low pressure Wasn't exactly sudden, since it took 90 seconds until the pressure dropped below the limits for humans to stay awake. The Challenger accident was likely the only true explosive decompression in spaceflight, since the destruction of the spacecraft and the primary structure of the cabin resulted in a sudden loss of pressure to the near vacuum at 25 km altitude.