The ‘intuitive’ strategy of building a compact electromagnet and placing it between Mars and the Sun at the first Lagrange point is unfeasible. The most feasible design is to encircle or wrap Mars at the equator with a superconducting wire loop. The resulting wire diameter could be as small as ∼5 cm. With this design, the magnetic shield would have a mass of ∼10^12 g and would require mining ∼10^18 g, or only 0.1% of Olympus Mons. https://arxiv.org/pdf/2006.05546.pdf