Well, it's powered by bleeding exhaust from a very big rocket.
I show someone and then I tell them, that's not the rocket exhaust. That's the exhaust for the engine that runs the fuel pump for the rocket.
Because weight is so critical, there's no luxury of "another component". If something can be repurposed, it is!
And the power opportunities afforded by continually dumping that much fuel through are mind boggling. Even regenerative cooling with combustive fuel blows my mind.