The liquid fuel rocket, which is continually being improved, is used in aircraft as well as for research in the upper air and for putting earth satellites into orbits.

液态燃料火箭不断得到改进，它用在飞行器上，也被用来研究高层大气和把地球卫星送入轨道。

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Water from asteroids could be broken down in space to liquid oxygen and liquid hydrogen for rocket fuel.

BBC: Plans for asteroid mining emerge

Liquid-fuelled rocket engines work by mixing the fuel (in this case kerosene) with liquid oxygen at high pressure.

ECONOMIST: On a rotor-blade and a prayer | The

The term hybrid is used because this type of rocket motor uses neither all-liquid fuel nor all-solid fuel, but a combination of both.

BBC: Hybrid success for British rocket