GaN HEMTs are prominent candidates for space applications, such as lunar mission, which demand reliable operation over a broad temperature range from 50K to 400K. Previous studies have characterized GaN HEMTs including cryogenic temperatures (typically down to 77K), but often with limited model numbers and sample sizes. To address this gap, a comprehensive comparative analysis of diverse GaN HEMTs is essential, taking into account the wide temperature range and statistical variations due to manufacturing inconsistencies. This digest provides a comprehensive characterization and analysis of GaN HEMTs, emphasizing the temperature-dependent behavior (50K to 400K) of their static characteristics. The study evaluates various GaN techniques, including semiconductor chips, packaging technologies, and voltage ratings. Additionally, it captures and quantifies statistical variations among samples of the same device model, offering insights for selection of suitable GaN techniques in space power design.