In this study, we used the PVD method by thermal evaporation technique, in which aluminum deposited on a 13 microm polyethylene terephthalate substrate. The aluminum deposition was carried out in different thicknesses (100, 150, 200, 250, 300 nm) on both sides of the substrate and two different deposition rates (a high rate of 6 nm/s and a low rate of 0.4 nm/s). Absorptance and emittance analyses were done. These analyses were evaluated by ECSS-Q70-71A standard for use in thermal blankets. According to analyses and evaluation, it was found that the sample with a thickness of 150 nm has the optimum values of absorptance and emittance for use in the thermal layers. Surface morphologies of the samples with the thicknesses of 100, 150, 200, 250, and 300 nm were investigated using AFM analysis. Other structural properties of the Al-PET sample with a thickness of 150 nm were determined by structural analyses, including XRD, FTIR, and FESEM.