A question always posed by someone who understands the principle of combustion ...
How do rockets work in space without the oxygen needed to burn fuel?
In order for the missiles to travel in space, the two most important components of the combustion reaction must be the fuel and the oxidizing material, so that all the rockets are equipped with their own fuel and oxidants. They do not need external oxygen.
In fact, oxygen-producing oxidants are not just oxygen. However, the mixture of liquid oxygen and liquid hydrogen is one of the most effective combustion mixtures.
Most rockets provide a reservoir of liquid oxygen, which acts as an oxidizer. It promotes combustion and maintains its continuity, and uses liquid hydrogen or kerosene as fuel in that case.
Solid power generators:
We do not need oxygen here; aluminum powder is used as fuel and ammonium perchlorate is oxidized.
Some rockets also use generators that rely on certain substances that generate the combustion reaction automatically when they interact with each other, such as hydrazine as fuel, and oxidants are nitrogen tetrazines.
Although oxygen is the most oxidizing on earth, we have other options available.

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Translated by: Dr. Heba Hafiri
Source https://www.scienceabc.com/nature/universe/since-fire-needs-oxygen-to-burn-how-do-rockets-work-in-the-vacuum-of-space.html