<p>Satellite instruments operate in harsh thermal environments in orbit, where temperature changes significantly impact the alignment of opto-mechanical structures. Temperature gradients, caused by environmental or internal heat sources, can lead to thermo-elastic deformations in the structure, resulting in undesirable image shifts and degraded optical payload performance. In this paper, finite element analysis was used to assess the dimensional stability of the payload barrel under temperature gradients during hot and cold phases in orbit. Systematic evaluations were conducted to understand the effects of temperature variations on the barrel’s physical geometry by measuring displacements and distortions between the front and rear optical lenses. The relative importance of different geometrical and material parameters in improving the dimensional stability of the barrel structure was identified. Furthermore, methods to enhance dimensional stability are discussed. The study found that barrel thickness is a critical geometrical factor in controlling displacement and distortion. Additionally, incorporating materials with lower thermal expansion through structural coupling techniques can improve structural stability and effectively maintain focal plane alignment.</p>