Bounds on Screened Dark Energy from Near-Earth Space-Based Measurements.

We test screened dark energy with near-Earth, space-based measurements. In a post-Newtonian framework, we compute leading corrections to geodetic precession (Gravity Probe B), LAGEOS-2 pericenter advance, and the Sagnac delay in a prospective orbital configuration, yielding bounds on chameleon, symmetron, and dilaton models. LAGEOS-2 sets the strongest Earth-orbit limits on symmetron and dilaton, while a Sagnac setup at the projected sensitivity of state-of-the-art space clocks gives the tightest chameleon constraint. These results show that low-density, space-based experiments sensitively probe screened dark energy and exclude previously allowed parameter space. Notably, at nuclear-clock precision O(10^{-19}), a Sagnac test would exclude the entire chameleon parameter space considered.