In outer space, there is less oxygen. How can it be managed by astronauts, and how many oxygen gallons can they carry with them? Do they have any alternate for oxygen there?
There is less oxygen, almost no oxygen in outer space. That is WHY they have a spacesuit in the first place. Otherwise:- The radiation from the sun on one side and the coldness of outer space from the other side will cause hypothermia and sunburn AT THE SAME TIME Since the pressure of outer space is practically zero, literally all the blood in your body will want to come out as fluids move from higher pressure to lower pressure. It's similar to a nose bleed people get when travelling to high altitudes, if they did not acclimatize well.