A laminar diffusion flame that is established over a spinning, thermoplastic, polymer fuel disk in a quiescent, oxidizing environment under microgravity is analyzed theoretically. The conservation equations for the polymer melt layer coupled to the gas-phase equations are solved numerically using similarity transformations. The polymer melting Fate, the thickness of the melt layer, and the fraction of melted fuel that is burned in the gas-phase are predicted as functions of the ambient conditions and polymer property values. In these Calculations the melt viscosity is assumed to vary with temperature in an Arrhenius form. Results are presented for polymethylmethacrylate (PMMA) disks burning in air at atmospheric pressure and compared against earlier experimental results. (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.