"The external tank held 535,000 gallons of propellants -- 390,000 gallons liquid hydrogen and 145,000 gallons liquid oxygen"
https://www.nasa.gov/centers/marshall/about/star/et_11.html
Propellants: Two Fuel Tanks (H2O) - One Oxidizer (Liquid Oxygen)
"splitting water by electrolysis and creating hydrogen/oxygen gas"
http://waterpoweredcar.com/
"What makes Brown's gas unique, and much more valuable, is that the hydrogen and oxygen have not formed into H2 and 02 molecules. They are in their monatomic (one atom per molecule) state. In this state, 3.8 times more energy will be returned when the hydrogen burns (combines with oxygen)."
https://www.fuelsaver-mpg.com/what-is-browns-gas?zenid=qgcr1nldm53198bth55in7n5g4
Four monatomic (one atom per molecule) Hydrogen
Two monatomic (one atom per molecule) Oxygen
Liquid O2 for remaining two monatomic (one atom per molecule) Hydrogen
"Liquid oxygen is the most common cryogenic liquid oxidizer propellant for spacecraft rocket applications, usually in combination with liquid hydrogen, kerosene or methane."
https://en.wikipedia.org/wiki/Liquid_oxygen
"Rockets must delicately balance and control powerful forces in order to make it through Earth's atmosphere into space.
A rocket generates thrust using a controlled explosion as the fuel and oxidant undergo a violent chemical reaction. Expanding gases from the explosion are pushed out of the back of the rocket through a nozzle."
https://www.space.com/how-rockets-work