Well this a way we can use to move in space without burning gas at least once in space. If we can find asteroids where we can mine for oxygen and hydrogen apart

Well this a way we can use to move in space without burning gas at least once in space. If we can find asteroids where we can mine for oxygen and hydrogen apart from metals for propulsion this to me could be the an actual way to make humanity a space faring civilization that at least travels in our solar system. Do we have the tech today to identify what asteroids are made out of from far away so we know where we need to send a spaceship first to mine