Originally Posted by
Wodrick
Looks like maybe an OAT probe, maybe not
Certainly looks to me to be a Total Air Temperature (TAT) probe - obviously fitted for flight test proposes. Airspeed probes nearly always have a round or oval inlet, for some reason the rectangular inlet is preferred for temp.
Just speculating - perhaps a different design probe, using flight test to verify it's performance vs. the normal TAT probe. Or maybe unheated, so that they can measure the effect of probe heat on the normal probe when not in icing or similar conditions.