For each adsorbent, we find the optimal storage pressure, P opt in eqn. 10, and the associated optimal tankage fraction, given in eqn. 11. Fig. summarizes the performance of the materials for adsorbed xenon propellant storage, with the aim of minimizing the mass of storage materials required to carry the xenon propellant into space. The x's in Fig. mark (P opt , ρ ads Xe (P opt )) for each adsorbent.