Robert Hutchings Goddard

Goddard was an American rocket engineer who was born in Worcester, Massachusetts, and educated at Worcester Polytechnic Institute and Clark University. Goddard's interest in rocketry developed in his childhood, and his interest helped him proposed his book on rocketry, "A Method of Reaching Extreme Altitudes." He tested the first engines that used liquid fuel in 1923 and launched the first liquid-fuel rocket. His other experiments included, construction of rockets that reached a velocity of 885 km/h (550 mph) and heights of up to 2 km (1.5 mi). Even though his work was practically ignored in his country at that time, it laid the foundation for later space explorations.

Wernher Von Braun

 In the World War II, a new weapon was used in battle. This was the V-2 rocket, which was a liquid-propellant rocket that was developed by the Germans. It was used as a guided missile in World War II, but later, it became a prototype for large space and missile rockets built in the United States and the Soviet Union. It leaves the earth's atmosphere during its high-arc flight to the target and had a range of 350 km (220 mi). A German named, Wernher Von Braun, was in charged of developing the V-2 rocket. After the World War II, the U.S. Army Ballistic Missile Agency research group, which was led by Wernher von Braun, had transferred to the civilian space agency. In 1960, this group became very successful and became the core of NASA's Marshall Space Flight Center in Huntsville, Alabama.