Your cardiovascular system is what moves blood through your body, delivering oxygen, nutrients, and more to its many cells. Those veins and arteries keep you alive. In your home, there are pipes that deliver water to different rooms of the house, helping you stay clean and hydrated.
It would be slightly worse than taking it off in space. The atmosphere on the surface of Mars is nearly a vacuum, so the astronaut would do well to notice the boiling saliva and tears and reseal the helmet immediately. Failing that, he or she would pass out in a few seconds, which is perhaps just as well. In space, you can only cool off by evaporation or by radiating infrared into space. On Mars, the tenuous air is just barely thick enough to conduct heat, and it’s generally colder than northern Siberia in the January. So…yeah. Don’t do that.
This is the order from top to bottom rounded; 0.24, 0.28, 0.30, 0.33
