How cold is it on Mars, really?

Roboramma said:
The post you responded to asserted that the problem is more shedding heat than preventing heat loss, so why the "heated fluid oversuit"? I can understand a need to prevent conductive heat loss if, for instance, a hand comes in contact with the ground, but the question is, do we actually have to worry about convective or radiative heat loss?

It seems that the answer is no and actually there's more concern with overheating than with preventing heat loss, though I haven't done the math to see who is right here.
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Looks like it may need to both functions, heating and cooling. The Spirit and Opportunity rovers measured temperatures from -80 to +30 (:jaw-dropp) deg C and that the temperature swings were enough to damage the rovers:

http://mars.nasa.gov/mer/spotlight/20070612.html
 
But the rovers don't produce much heat of their own, whereas a human body does. Even at -80, do we really need to worry much about heat loss?

As I said I can see issues with conductive heat loss when touching the ground, for instance. Probably easy to get frost bit without decent protection in that case, but aside from actual contact with very cold materials, in general I'd suspect that even in very cold temperatures the issue would be more one of how to get rid of excess heat, not how to insulate and prevent heat loss.
 
Mikemcc said:
Looks like it may need to both functions, heating and cooling. The Spirit and Opportunity rovers measured temperatures from -80 to +30 (:jaw-dropp) deg C and that the temperature swings were enough to damage the rovers:

http://mars.nasa.gov/mer/spotlight/20070612.html
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From something I read a while ago (probably a sci-fi story), I believe the ~30C temperature would be (literally) a surface temperature. At, say, 1.8m (head height for an astronaut), it would be considerably less. Viking measured soil temps of about 27C from infrared, but the air temperature at 1.5m was roughly -17C.
http://www-k12.atmos.washington.edu/k12/resources/mars_data-information/temperature_overview.html
 
This is why I don't think Mars should be our first choice for the first large scale, permanent or semi-permanent (i.e the first thing that could properly be thought of as a settlement or colony instead of a "base" or expedition or scientific outpost or whatnot) and Europa or Titan or our Moon should be our areas of focus.

But at times I also wonder if the effort into settling on a planet wouldn't just be an equal sunk cost as being a large self sufficient space station.
 
JoeBentley said:
But at times I also wonder if the effort into settling on a planet wouldn't just be an equal sunk cost as being a large self sufficient space station.
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A planet has lots od readily available land and mineral resources. A planet with water should have rich mineral veins just waiting to be harvested. These two alone are more than enough to make a planet a better choice for colonization than a space station could.

McHrozni
 
JoeBentley said:
This is why I don't think Mars should be our first choice for the first large scale, permanent or semi-permanent (i.e the first thing that could properly be thought of as a settlement or colony instead of a "base" or expedition or scientific outpost or whatnot) and Europa or Titan or our Moon should be our areas of focus..
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1. How would the moon be any better? Solar radiation exposure would as great if not greater. (no atmosphere at all and closer to the Sun)

2. Europa is years of traveltime, and in any case, its bombarded with 540 rem of radiation per day in the form of high-energy electrons and ions, mostly from Jupiter. That is around 18,000 times what the surface of Mars receives.

3. Titan? That is at least a ten year trip just to get manned spacecraft there. Yes, other unmanned missions have got there quicker, but that was using gravity assist from Jupiter that accelerated them to a speeds from which it would be difficult to slow down and get into orbit.
 
Roboramma said:
But the rovers don't produce much heat of their own, whereas a human body does. Even at -80, do we really need to worry much about heat loss?

As I said I can see issues with conductive heat loss when touching the ground, for instance. Probably easy to get frost bit without decent protection in that case, but aside from actual contact with very cold materials, in general I'd suspect that even in very cold temperatures the issue would be more one of how to get rid of excess heat, not how to insulate and prevent heat loss.
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It appears that the human body ditches heat primarily by radiation (approx. 65%), how that is changed by wearing a suit I don't know.

One idea could also use the body itself to help maintain the suit environment. Use wicking base layers and draw off the damp air and de-hydrate it, recover the water, scrub the CO2, and recirculate the air as much as possible. The perspiration is one hell of a way to keep the body temperature down.
 
smartcooky said:
1. How would the moon be any better? Solar radiation exposure would as great if not greater. (no atmosphere at all and closer to the Sun)
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Because the moon is right next door astronomically speaking. We'd be facing the same (or only slightly worse) issues with radiation, temperature, etc but that would be, in my opinion, highly offset by a 2-3 day travel time (versus a travel time so long it pretty much every scenario I've seen requires a one way trip) and (near) instantaneous communications. We took off and landed on the moon nearly 50 years ago. It's a proven place we can get to and get back to. If we had a permanent moon base we could get emergency supplies to it in a pinch. We could medevac someone from it in a pinch. We could talk them through problems in (more or less) real time. They wouldn't be quite as "on their own."

Europa is years of traveltime, and in any case, its bombarded with 540 rem of radiation per day in the form of high-energy electrons and ions, mostly from Jupiter. That is around 18,000 times what the surface of Mars receives.
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Probable liquid water which to me at least offsets pretty much any other issue beyond "populated by a race of sentient Youtube comments"

There is no such thing as a perfect (or even good if you want to be honest) site in our solar system for a permanent human settlement with our current technology, any place is going to take a lot of work.
 
Hopeful Parallel said:
I've read that mars is colder than the earth. The parts of Mars have been known to drop as low as 123 C.
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Yeah, I've even heard that it's so cold there I heard that there have been times where some places on the planet's surface have reached below the boiling temperature of water!
 
How cold is it on Mars? Well, see for yourself: http://www.space.com/16907-what-is-the-temperature-of-mars.html

"On average, the temperature on Mars is about minus 80 degrees F (minus 60 degrees C). In winter, near the poles temperatures can get down to minus 195 degrees F (minus 125 degrees C). A summer day on Mars may get up to 70 degrees F (20 degrees C) near the equator, but at night the temperature can plummet to about minus 100 degrees F (minus 73 C)"​

I believe that in scientific terms, it's called 'colder than a brass monkey's balls.' ;)
 
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Mikemcc said:
Looks like it may need to both functions, heating and cooling. The Spirit and Opportunity rovers measured temperatures from -80 to +30 (:jaw-dropp) deg C and that the temperature swings were enough to damage the rovers:

http://mars.nasa.gov/mer/spotlight/20070612.html
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Hmmm, reminds me of home.
Our temp swings here are between extremes of <-40C to +35C.
Vehicles just don't behave well at -40 and below.
 
HansMustermann said:
How cold is it on Mars? Well, see for yourself: http://www.space.com/16907-what-is-the-temperature-of-mars.html

"On average, the temperature on Mars is about minus 80 degrees F (minus 60 degrees C). In winter, near the poles temperatures can get down to minus 195 degrees F (minus 125 degrees C). A summer day on Mars may get up to 70 degrees F (20 degrees C) near the equator, but at night the temperature can plummet to about minus 100 degrees F (minus 73 C)"​

I believe that in scientific terms, it's called 'colder than a brass monkey's balls.' ;)
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"Cold enough to freeze the balls off a brass monkey"
 
But the point of this thread, right from the start, is that temperature alone says very little. Temperature alone does not say how much heat will be transferred away from bodies. For that you need thermal capacity of the surrounding medium .. and we know it is very low on Mars, mostly due very low pressure and thus density of the surrounding medium.
So while brass monkey's balls would indeed over time get down to minus 60, live monkey's balls would not.
 
Mikemcc said:
Looks like it may need to both functions, heating and cooling. The Spirit and Opportunity rovers measured temperatures from -80 to +30 (:jaw-dropp) deg C and that the temperature swings were enough to damage the rovers:

http://mars.nasa.gov/mer/spotlight/20070612.html
Click to expand...

Roboramma said:
But the rovers don't produce much heat of their own, whereas a human body does. Even at -80, do we really need to worry much about heat loss?
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Don't underestimate the RTGs, they're typically <6% efficient at converting the decay heat into electricity so most of the energy produced is heat. The eight plutonium modules each produce about 250W of thermal energy (and in total about 110W of electric power). That's a lot more waste heat than a human.
 
Dr.Sid said:
But the point of this thread, right from the start, is that temperature alone says very little. Temperature alone does not say how much heat will be transferred away from bodies. For that you need thermal capacity of the surrounding medium .. and we know it is very low on Mars, mostly due very low pressure and thus density of the surrounding medium.
So while brass monkey's balls would indeed over time get down to minus 60, live monkey's balls would not.
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Live monkey (or any primate) lungs might suffer from the low pressure though.
 
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