This grant opportunity is part of NASA's annual omnibus Research Opportunities in Space and Earth Sciences (ROSES) for 2025. It supports research in heliophysics, specifically theory, modeling, and simulations related to space weather and solar-terrestrial interactions. The goal is to advance scientific understanding of the fundamental processes in heliophysics and their impact on the Earth and the broader space environment. Funding is available for U.S. institutions, with some opportunities for international participation under no-exchange-of-funds policies. Awards will primarily be issued as grants or cooperative agreements, with a typical period of performance of three years, though some projects may extend up to five years.