7. The Scientists - Red Planet
This one is going to be short and to the point. A group of astronauts with the same type of backing as astronauts get today (these guys are not poorly funded) get sent to Mars to discover what has happened to a terraforming colony there that has suddenly quit producing results. When they arrive their ship gets damaged and they quickly run out of oxygen in their tanks. They begin to suffocate to death when one of them out of sheer desperation takes off his helmet and realizes, "Hey guys, the air, I can breathe it!" The air on Mars had been turned into oxygen this whole time, but neither they nor the group that sent them noticed this?