Potential of Constraining the Fifth Force Using the Earth as a Spin and Mass Source from Space

We explore the potential of conducting an experiment in a low Earth orbit spacecraft and using the Earth as a spin and mass source to constrain beyond-the-standard-model (BSM) long-range spin- and velocity-dependent interactions, which are mediated by the exchange of an ultralight ( m Z ′ < 10 −10 eV) or massless intermediate vector boson. The high speed of low-Earth-orbit spacecraft can enhance their sensitivity to velocity-dependent interactions. This periodicity enables efficient signal extraction from background noise, thereby improving the accuracy of the experiment. Combining these advantages, we theoretically demonstrate that the novel spacecraft-Earth model can improve the existing bounds on these exotic interactions by up to three orders of magnitude using the China Space Station (CSS) as a representative low-Earth-orbit carrier. If successfully implemented, this model may provide an innovative strategy for detecting ultralight dark matter and yield tighter constraints on certain coupling constants of exotic interactions.