Three Zn-doped InSb crystals were directionally solidified under microgravity conditions at the International Space Station (ISS) Alpha. The distribution of the Zn was measured using SIMS. A short diffusion-controlled transient, typical for systems with k > 1 was demonstrated. Static pressure of similar to 4000 N/m(2) was imposed on the melt, to prevent bubble formation and de-wetting. Still, partial de-wetting has occurred in one experiment, and apparently has disturbed the diffusive transport of Zn in the melt. (C) 2009 Elsevier B.V. All rights reserved.