In 1919, the American scientist Robert H. Goddard designed what significant invention?

The significant invention designed by Robert H. Goddard in 1919 was the liquid-fuelled rocket. Goddard is often referred to as the father of modern rocketry due to his pioneering work in developing the first successful liquid-fueled rocket in 1926, but his designs and concepts laid the groundwork for that achievement. The use of liquid fuel allowed for greater efficiency and control compared to solid propellants, which were used in earlier rocket designs. This marked a pivotal moment in the field of rocketry and eventually led to advancements in space exploration and satellite technology. The principles he established are still fundamental to rocket science today.