Velocity curves for different bare spacecraft masses (m₀ = 1, 10 g) and DE system sizes (d = 1, 10 km). We assume a 100 GW DE system and the optimal case where m_s = m₀. The sail is assumed to have thickness 1 μm and density 1400 kg m⁻³. The 1 km DE system has a larger beam divergence than the 10 km system. As a result, spacecraft propelled by the 1 km DE system spend less time in the ﹩x\lt {L}_{0}﹩ regime and have lower terminal velocities. Gram-scale spacecraft accelerate extremely quickly reaching their relativistic terminal velocity in a matter of minutes.