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Why only rocket engines can operate in space Select the key reason rockets are the only engines that can propel vehicles in outer space where there is no atmosphere. Choose the correct option.

Difficulty: Easy

They can generate very high thrust
They have high propulsion efficiency
They can work on several different fuels
They are not air-breathing engines

Correct Answer: They are not air-breathing engines

Explanation:

Given data

Space environment lacks atmospheric oxygen.

Concept/Approach
Rocket engines carry both fuel and oxidizer and therefore do not rely on atmospheric air. Air-breathing engines (turbojets, turbofans, ramjets) cannot operate in vacuum due to lack of oxygen mass flow.

Final Answer
They are not air-breathing engines

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