and eventually abandoned the plan around 2018. Falcon 9 second stage in flights prior to that were left in orbit. Controlled de-orbit is the simplest first step required in the challenging orbital speed recovery. The capability was acquired in recovery development.SpaceX intended (from at least 2014) to develop technology to extend reusable flight hardware to second stages, a more challenging engineering problem because the vehicle is travelling at orbital velocity.[5][4][6] Second stage reuse is considered paramount to Elon Musk's plans to enable the settlement of Mars. Initial concepts to make the second stage of Falcon 9 reusable have been abandoned.[7]
As for the debris made from composite material, it's shown in the news footage clip.
Related link: SpaceX reusable launch system development program
