We're zombies bro!! Zombies don't need oxygen!

I'm not sure about the best way to explain the technicalities of how well the respiratory system works in a vacuum. But if I had to condense it, it does not. Humans do not survive in a vacuum for more than a few seconds at most. And would require extensive medical treatment afterwords. Assuming they even survived in the first place (<3% chance if I wanted to be very generous). As for why on the other planets, let's start with Venus. The actual planet Venus gets to be about 900° Celsius or so. I may be off by as much as 100° or so but it wouldn't matter to a human as they would instantly burst into flame anyway, assuming you survived the 90x atmospheric pressure currently on the planet. The Venus on destiny likely has a much more supportive atmosphere, although it appears to have a fairly good amount of rain, which based on the volcanic activity would most likely be liquid sulfuric acid in some concentration. So, if you took your helmet off in even a place where you weren't being directly rained on, you would probably suffer a very painful death as the fumes off the acid (which the air would be quite saturated with) burned your eyeballs, nose, lungs, and every inch of exposed skin. As for Mars, it would probably be the most livable. The current Mars lacks enough of an atmosphere to insulate the surface to stay warm. The destiny Mars probably has that, as well as deposits of water. But enough about Mars The moon. Did anyone else notice that the fallen on the moon walk around with their faces exposed? Normally If you tried that on the current moon your eyeballs would pop out of your head due to the pressure difference in the atmosphere. Which is likely how the cabal die when you shoot their helmets off.

Only at night when the sun is down

You are forgetting that we have space magic.

You had a 2 hour debate with a wall? Damn.

What if you're an exo? Also you can have your mask off in the reef which is on an open port in space.. Video game logic man... Crazy stuff. :b

A 2hr debate? You both know where the tower is right?

You can breathe but it doesn't mean you'll survive it.

It's implied at one point that the leaking fumes on the Cabal ship are hazardous. That and the fact that you can never remove your helmet anywhere else other than at the Tower on Earth heavily implies that you rely on some sort of oxygen system to breathe elsewhere. Maybe a portable system that is integrated to your armor or something similar that the ghost has access to.

I think your friend is disabled, you shouldn't be so judgmental of disabled people gosshh If, in the case of your friend not having any disability, he is really very unintelligent... [spoiler]or he's like, 6 or something[/spoiler]