• Question: If the liquid fuel is liquid oxygen what is the solid fuel

    Asked by Soyuz Guru to RocketRich, Elie on 7 Mar 2016.
    • Photo: Richard Moss

      Richard Moss answered on 7 Mar 2016:

      Cars burn fuel by mixing it with oxygen from the air. Rockets must carry the oxygen with them. Some use liquid (super cold air!) and others use solid. In both cases there are chemicals which burn and other chemicals which contain oxygen.

    • Photo: Elie Allouis

      Elie Allouis answered on 7 Mar 2016:

      Well that’s an interesting one!
      To burn, things need oxygen and fuel.

      The liquid oxygen in liquid fuel propulsion is not actually the fuel itself. It just helps it burn. Depending on the system, liquid fuels can be Hydrogen (like Ariane 5 main stage), or some other chemical like kerosene. The benefit of liquid fuel is that you can turn it off if you needed to.

      Solid fuels like in solid rocket boosters is a mixture of chemical providing the oxygen and the fuel…so it does not need anything else. …but once it starts burning,… there is no turning back…

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