in an arctic environment
The big problem with these wild expeditiona is mainly frostbite (provided that you survive at all of course). To prevent frostbite on such treks, I suggest the following mechanisms. Maybe they've been thought of before and don't work for some reason. I don't really know ... or care for that matter because I'll never go on such a trip myself. Hell, my nose ain't gonna' freeze off so ... what?
Where can we get some heat?
You can't use batteries to run heaters. They'd run out of juice on an extended trip and probably would fail anyway if they had any electronic components in them. It has to be elementary and use your own body's heat source. So I propose to borrow heat from under your armpits to heat your fingers ... heat from between your thighs to warm your toes ... and heat from your belly to warm your nose, lips and face.
Let's do the face job first.
The key here is to pre-heat the air you breathe in. By sucking in warmer air, you nose and mouth will not freeze up so readily. You'll be wearing a mask with a hose connected to a bladder under your parka and shirt ... right next to your belly fat. Like this.
At "A", there are tubes made of short copper pieces connected with plastic to make them flexible. The plastic connectors have holes in them to take in air under your clothes. These connect to larger plastic tubes that all go to the nose piece where you breathe in fresh air. As the air moves near your belly, it picks up heat and your belly gets colder in exchange. We don't want to take too much heat ... just enough to prevent frostbite at the nose and mouth. There are check valves at "C" in both the intake and outflow to force a one way flow of air. The exit hose ("B") is large and flexible and will accumulate ice. You can knock it loose by flexing the hose. It must be made of material that will not freeze and will remain flexible at very low temperatures ... and ... ice should fall off of it easily. The intake hoses at the nose should arch up so no condensation can run down to the check valve and foul it.
For the fingers and toes ...
We do the same as above ... except ... that we will have a closed system, i.e. the same air is circulated constantly. We don't have to worry about condensation as in a breathing apparatus. So we will have two sets of copper tubes: one to pick up heat at the armpits (or thighs) and another set to give up heat to the fingers and toes (shown schematically at right). The heat will have to be relinquished on the tops of the fingers so that the sense of touch isn't interferred with. But the copper tubing could be under the toes. Check valves keep the air going in one direction. And to propel it ... we need a pump that will operate more or less without our having to consciously work it. It must work off the normal action of the limbs like walking or swinging the arms or picking up things. A bladder with a flat spring inside to cause it to expand would do. When you press your arm against your side ... it pumps air through the system ... or ... you flex your arm and a piston moves in a cylinder ... something like that. A pump bladder under your foot could expand when you pick up your foot to walk and pump air through when you put your weight back on it. Some experiment is needed to see what works best but some simple setup will certainly work ... something "off the shelf".
What happens when you go to sleep?
Do you freeze to death without your pumps working. After all, they only work if you're moving around. Here is a good use for the "Hilsch Tube". This gizmo has no moving parts and takes a high pressure air input into a "swirl" chamber where it rotates and this empties into two pipes one of which is cold and the other hot. It separates the hot molecules from the cool. It's quite inefficient but it has some esoteric uses.
What I envision is a tent out on the tundra or ice (whereever) and the wind is howling outside.
But this time there is an anemometer gizmo which drives a small compressor which blows arctic air into a Hilsch tube ... which separates the warmer molecules from the Mars-freezing ones ... which jacks into a hose connected to your internal air flow thingies ... and you get heated as you sleep and the Mars-air gets vented outside the tent. Sweet.