Liquid hydrogen (LH2), known for its lightweight characteristics, has long served as the preferred power source for rockets, propelling both equipment and personnel into space. Modern spacecraft models not only rely on LH2 for combustion but also utilize it in fuel cell power generation.

LH2, deemed ideal for powering upper stages of rockets after liftoff, has been instrumental in significant space missions, such as the Apollo program that successfully landed astronauts on the moon. It has powered the second-stage engines of Saturn rockets, and NASA's Space Shuttle relied on LH2 to fuel its three main rocket engines.

Beyond its historical significance, hydrogen's lightweight nature presents a compelling advantage for space-bound rockets. As engineers strive to optimize energy density within the constraints of weight limitations, each kilogram sent into space incurs substantial costs-both in terms of finances and spacecraft performance.