Robert H. Goddard - A Method of Reaching Extreme Altitudes

In 1919, the Smithsonian Institution published Goddard's groundbreaking work, A Method of Reaching Extreme Altitudes. The report describes Goddard's mathematical theories of rocket flight, his experiments with solid-fuel rockets, and the possibilities he saw of exploring the Earth's atmosphere and beyond. Along with Konstantin Tsiolkovsky's earlier work, The Exploration of Cosmic Space by Means of Reaction Devices. 1903., Goddard's little book is regarded as one of the pioneering works of the science of rocketry. It was distributed worldwide.

Goddard described extensive experiments with solid-fuel rocket engines burning high grade nitrocellulose smokeless powder. A critical breakthrough was the use of the steam turbine nozzle invented by the Swedish inventor Gustaf de Laval. The de Laval nozzle allows the most efficient ("isentropic") conversion of the energy of hot gases into forward motion. By means of this nozzle, Goddard increased the efficiency of his rocket engines from 2 percent to 64 percent and obtained supersonic exhaust speeds of over Mach 7.

Though most of this work dealt with the theoretical and experimental relations between propellant, rocket mass, thrust, and velocity, a final section, entitled "Calculation of minimum mass required to raise one pound to an 'infinite' altitude", discussed the possible uses of rockets, not only to reach the upper atmosphere, but to escape from Earth's gravitation altogether. Included as a thought experiment was the idea of launching a rocket to the moon and igniting a mass of flash powder on its surface, so as to be visible through a telescope. He discussed the matter seriously, down to an estimate of the amount of powder required; Goddard's conclusion was that a rocket with starting mass of 3.21 tons could produce a flash "just visible" from Earth.

Goddard eschewed publicity, because he did not have time to reply to criticism of his work, and his imaginative ideas about space travel were shared only with private groups he trusted. He did, though, publish and talk about the rocket principle and sounding rockets, since these subjects were not too "far out." In a letter to the Smithsonian, dated March 1920, he discussed: photographing the Moon and planets from rocket-powered fly-by probes, sending messages to distant civilizations on inscribed metal plates, the use of solar energy in space, and the idea of high-velocity ion propulsion. In that same letter, Goddard clearly describes the concept of the ablative heat shield, suggesting the landing apparatus be covered with "layers of a very infusible hard substance with layers of a poor heat conductor between" designed to erode in the same way as the surface of a meteor.

Every vision is a joke until the first man accomplishes it; once realized, it becomes commonplace.

“ ” Response to a reporter's question following criticism in The New York Times, 1920.