Porous materials exhibiting aligned, elongated pore structures can be created by directional solidification of aqueous suspensions-where particles are rejected from a propagating ice front and form interdendritic, particle-packed walls-followed by sublimation of the ice and sintering of the particle walls. Theoretical models that predict dendritic lamellae spacing-and thus wall and pore width in the final materials-are currently limited due to an inability to account for gravitydriven convective effects during solidification. Here, aqueous suspensions of 10-30 nm TiO 2 nanoparticles are solidified on parabolic flights under micro-, lunar, and Martian gravity and compared to terrestrially-solidified samples. After ice sublimation and sintering, all resulting TiO 2 materials exhibit elongated lamellar pores replicating the ice dendrites. Increasing the TiO 2 fraction in the suspensions leads to decreased lamellar spacing in all samples, regardless of gravitational acceleration. Consistent with previous studies of microgravity solidification of binary metallic alloys, lamellar spacing decreases with increasing gravitational acceleration. Mean lamellar spacing for 20 wt.% TiO 2 nanoparticles suspensions under micro-, lunar, Martian, and terrestrial gravity are, respectively: 50±8, 34±11, 30±6, and 23±9 μm, indicating that gravity-driven convection strongly affects lamellae spacing under terrestrial gravity conditions. Gravitational effects on lamellar spacing are highest at low TiO 2 fractions in the suspension; for 5 wt.% TiO 2