Dr. Daniel Kleppner's groundbreaking research on hydrogen had a profound impact on various fields of physics. By developing a method to study hydrogen atoms' quantum properties, he and Norman Ramsey co-invented the hydrogen maser in 1960, a pivotal advancement that enabled the precise measurement of time and played a key role in the development of GPS. Dr. Kleppner's work on Rydberg atoms laid the groundwork for modern Rydberg quantum computers, while his collaboration on achieving Bose-Einstein condensation in hydrogen led to significant discoveries and earned his team a Nobel Prize. His contributions to ultracold gases research, boost-phase missile defense, and the establishment of the Center for Ultracold Atoms further highlight his impactful career in atomic physics.