These grid aerobrakes/drag control moving surfaces, have been used for a while on various aerodynamic designs, and presumably they provide a turbulent airflow, which in some way is more predictable than a laminar one, since it never switches between laminar and turbulent. Assuming that a turbulent behaviour is necessary for booster reentry(?), why does it seem like this design is a copy/paste from the past? Are there any other proposals or tests made for this particular aerodynamic part? (maybe with a different grid scale, no grid at all and a different volume/surface ratio, or a totally different shape)?
Thanks for the answer, the idea was also to question the simplicity of the falcon 9 concept, amount of moving parts, landing fuel weight. I was wondering if those fins could be longer, deploy slowly to aerobrake, and when subsonic pitch them in order to land in autorotation, with no fuel at all.