He later wrote in his autobiography about an inspiration that came to him as a boy. While his family was staying at the suburban home of friends in Worcester, on October 19, 1899, he climbed into an old cherry tree to prune its dead branches. Instead, he began daydreaming: "It was one of the quiet, colorful afternoons of sheer beauty which we have in October in New England, and as I looked toward the fields at the east, I imagined how wonderful it would be to make some device which had even the possibility of ascending to Mars, and how it would look on a small scale, if sent up from the meadow at my feet."
"I was a different boy when I descended the tree from when I ascended, for existence at last seemed very purposive."
October 19 became "Anniversary Day," noted in his diary as his personal holiday.
Five years later, after graduating from school, Robert Goddard applied and was accepted at Worcester Polytechnic Institute. In 1907, while a student at Worcester Polytechnic Institute in Massachusetts, Goddard experimented on a rocket powered by gunpowder in the basement of the physics building. Clouds of smoke caused a lot of commotion and the faculty, rather than expel him, took an interest in his work.
He received his degree in physics in 1908 and was made a Fellow in the physics department at Clark University. There, he received his master's degree in 1910 and in 1911 he received his doctorate.
By 1914, Goddard already had received two U.S. patents (#1,103,503 and #1,102,653): one for a rocket using liquid fuel and the other for a two- or three-stage rocket using solid fuel. Until that time, propulsion was provided by various types of gunpowder.
That year, he began teaching physics at Clark University in Worcester. His thoughts on space flight started to emerge in 1915, when he theorized that a rocket would work in a vacuum, and didn't need to push against air in order to fly. This meant that in the vacuum of space, rocket engines would be able to produce thrust. At his own expense, he began to make systematic studies about propulsion provided by various types of gunpowder. He began experiments on the efficiency of rockets. He bought some commercial rockets and measured their thrust using a ballistic pendulum, a heavy mass suspended by ropes, to which the rocket was attached. The rocket was fired, and the height to which the pendulum rose provided a measure of the total momentum (mass times velocity) imparted to it. Goddard also used an equivalent set-up, where the mass pushed against a spring, instead of being suspended.
His classic document was a study that he wrote in 1916 requesting funds of the Smithsonian Institution so that he could continue his research. This was later published along with his subsequent research and Navy work in a Smithsonian Miscellaneous Publication No. 2540 (January 1920). It was entitled "A Method of Reaching Extreme Altitudes." In this treatise, he detailed his search for methods of raising weather recording instruments higher than sounding balloons. In this search, as he related, he developed the mathematical theories of rocket propulsion.
Goddard's discoveries were given little attention by the U.S. government. Funding from the Smithsonian Institution allowed Goddard to continue his rocket research and develop the mathematical theories of rocket propulsion. In 1920, the Smithsonian published his original paper, "A Method for Reaching Extreme Altitudes," in which he included a small section stressing that rockets could be used to send payloads to the Moon exploding a load of flash powder there to mark its arrival. The bulk of his scientific report to the Smithsonian was a dry explanation of how he used the $5000 grant in his research. Yet, the press picked up Goddard's scientific proposal about a rocket flight to the moon and erected a journalistic controversy concerning the feasibility of such a thing. Much ridicule came Goddard's way. And he reached firm convictions about the virtues of the press corps which he held for the rest of his life.
He responded to a reporter's question by stating, "Every vision is a joke until the first man accomplishes it; once realized, it becomes commonplace."