Although, I'm not particularly knowledgable in this specific area, I'm just curious as to how the atmosphere of some of these planets works. If I'm correct, Mars' atmosphere is basically gone, so wouldn't that make it difficult for us to survive, even momentarily, on Mars? Unless we terraform, but seeing as its been awhile since we've been there (canonically), I'm not sure how that technology would still be working. Besides, the enemies we will encounter there seem pretty anti-human and might destroy that equipment. I've heard things like face masks and whatnot, but even still, intense sun light is harmful to our skin, even with armor. Let me know what you guys think.