Fill the gaps in the sentences using words and phrases in the box.
The first person to study in detail the use of rockets for spaceflight was the Russian schoolteacher and mathematician Konstantin Tsiolkovsky. In 1903 his article "Exploration of Cosmic Space by Means of Reaction Devices" 1._________________
of spaceflight. Up to his death in 1935, Tsiolkovsky continued to publish sophisticated studies on the theoretical aspects of spaceflight. He never 2.___________
his writings with practical experiments in rocketry, but his work greatly influenced later space and rocket research in the Soviet Union and Europe.
In the United States, Robert Hutchings Goddard became interested in space exploration after reading works such as The War of the Worlds. Even as a young man, he dedicated himself to working on spaceflight. Goddard received his first two patents for rocket technology in 1914, and, with funding from the Smithsonian Institution, he published a theoretical treatise, A Method of Reaching Extreme Altitudes, in 1919. Goddard's claim that rockets could be used to send objects as far as the Moon 3.__________________
, including The New York Times. Thereafter, the already shy Goddard conducted much of his work in secret, preferring to patent rather than publish his results. This approach limited his influence on the development of American rocketry, although early rocket developers in Germany 4.___________________
The third widely recognized pioneer of rocketry, Hermann Oberth, was by birth a Romanian but by nationality a German. Reading Verne's From the Earth to the Moon as a youth inspired him to study 5.________________
. Oberth's 1922 doctoral dissertation on rocket-powered flight was rejected by the University of Heidelberg for being too speculative, but it became the basis for his classic 1923 book Die Rakete zu den Planetenräumen ("The Rocket into Interplanetary Space"). The work explained the possibility of constructing space stations and of traveling to other planets.
In 1929 Oberth published a second influential book, Wege zur Raumschiffahrt (Ways to Spaceflight). His works led to the creation of a number of rocket clubs in Germany as enthusiasts 6._______________
. The most important of these groups historically was the Verein für Raumschiffahrt (VfR; "Society for Spaceship Travel"), which had as a member the young Wernher von Braun. Although Oberth's work was 7.___________
in stimulating the development of rocketry in Germany, he himself had only a limited role in that development. Alone among the rocket pioneers, Oberth lived to see his ideas become reality: he was Braun's guest at the July 16, 1969, launch of Apollo 11. https://www.britannica.com/science/space-exploration/History-of-space-exploration