Which figure contributed significantly to the theoretical aspects of rocketry?

Konstantin Tsiolkovsky is a pivotal figure in the theoretical aspects of rocketry because he is often credited with laying the groundwork for modern astronautics. His formulation of the rocket equation, which describes the motion of rockets and is critical for understanding how they can travel in space, is fundamental to the field. Tsiolkovsky also envisioned the idea of space travel and proposed concepts such as using liquid propellants and the concept of a multistage rocket, which directly influenced future rocket designs and missions.

His work, published in the early 20th century, formed the basis of much of the theoretical framework that later engineers and scientists built upon. This makes him a cornerstone figure in the development of rocketry, differentiating his contributions from those of others, who may have focused more on practical applications or specific technologies rather than foundational theory.