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Antiparticles have a mass‐based energy density nearly 10 orders of magnitude greater than the best chemical propellants. This attribute, particularly with antiprotons, enables exciting new approaches to spacecraft propulsion and design. However, these advantages have not been realized due to the inherent limitations associated with the artificial production and storage of the antiparticles. In comparison, antiparticles are produced and trapped naturally in the space environment due to the interaction of high‐energy galactic cosmic rays (GCR) with residual matter in the interstellar medium and around solar system bodies. We assess the stable and transient antiparticle content of these sources and subsequently consider their capture and application to high delta‐v space propulsion.The magnetosphere surrounding a planet offers a unique environment for the generation and trapping of antiprotons. Using Earth’s magnetic field as an example, we have considered the various source mechanisms that are applicable to a planetary magnetosphere, the confinement duration versus transport processes, and the antiparticle loss mechanisms. We have estimated the trapped population of antiprotons magnetically confined following production in the atmosphere due to nuclear interactions between high‐energy cosmic rays and constituents of the residual planetary atmosphere. We present results of the estimated particle fluxes due to pair production of antiprotons in the exosphere, the decay of albedo antineutrons generated in the atmosphere, and the focusing the transient GCR antiprotons by the magnetic field of the planet. We discuss relevant scaling parameters and extend the terrestrial results to the Jovian planets and other solar system objects to estimate the total supply of antiprotons surrounding these bodies.The expediency of utilizing an electromagnetic scoop to extract antiparticles for practical use is subsequently considered. A large scale magnetic field generated by a spacecraft can be used as a funnel to direct charged antiparticles towards a trap. We discuss and explore the fundamental performance limits of such a device and estimate the total antiproton collection rate for a given flux level. Based on predicted fluxes, it is potentially feasible to extract tens to hundreds of micrograms of antiprotons from the natural environment over the course of a year. Near the throat of the collection device, the particle can be transferred to closed field lines where it is stably trapped in the mini‐magnetosphere that is formed in the space surrounding the exterior of the vehicle. Following capture and trapping, the particles can be used as a fuel for propelling spacecraft to high velocities.