Constraints on fifth forces and ultralight dark matter from OSIRIS-REx target asteroid Bennu

Using the OSIRIS-REx mission and ground-based tracking data for the asteroid Bennu, we derive new constraints on fifth forces and ultralight dark matter. The bounds we obtain are strongest for mediator masses $m \sim 10^{-18} - 10^{-17}\,{\rm eV}$, where we currently achieve the tightest bounds. Our limits can be translated to a wide class of models leading to Yukawa-type fifth forces, and we demonstrate how they apply to $U(1)_B$ dark photons and baryon-coupled scalars. Our results demonstrate the potential of asteroid tracking in probing well-motivated extensions of the Standard Model and ultralight dark matter satisfying the fuzzy dark matter constraints.