Living on Mars

Life here on Mars is different from Earth. We spend a lot of time inside, and that means we have to keep a very clean house (which we call the Habitat, or just the Hab). Whenever we go outside, we have to wear spacesuits, because the surface of Mars doesn't have enough air. The suits provide us with air (that's what the big backpack is for, although the helmet keeps it close to us so we can breathe it) and protection from other things. We still have to shield ourselves from the sun on Mars (you can see me wearing sunglasses and a hood to prevent sunburn), but some spacesuits have visors that slide down over the helmet, so we don't have to wear sunglasses inside the helmet. There is actually less sunshine on Mars, because it is farther from the Sun. The intensity of sunlight shrinks in inverse proportion to the square of the distance from the Sun, for those algebra fans reading this. That means that, since Mars is about 1.5 times the distance from the Sun that the Earth is, it gets only about 45% as much sunlight. Bonus points to anybody who can figure out how much sunlight Mars would get if it were 2.5 times the distance from the Sun that the Earth is (answer below).

However, Mars has a thinner atmosphere, and atmosphere absorbs radiation from the Sun - the Sun emits more than just light; it also radiates in the infrared, ultraviolet, and other bands. Infrared is heat, which helps explain why Mars is colder than Earth - it gets less heat from the Sun. Its atmosphere also absorbs less heat, because it is thinner, so Mars gets colder at night than Earth does.

Life on Mars means living very closely with other people - I and my seven new best friends are living in the small habitat, with only a few chances to go outside. I got sick last night, so now I am running around with a mask on to prevent spreading my germs to the rest of the crew, and I am washing my hands every chance I get. If we all get sick, nobody will be happy. Fortunately, we have a lot of medical supplies here, and there is a doctor who is always ready to talk to us. He isn't here, but he does what is called "telemedicine." That means he gives medical advice based on what he is told over email. Fortunately, he was able to advise on my condition, and after a night spent sleeping by a space heater, I feel a little better.

Answer: 16%