Tsiolkovsky would remain in Kaluga until his death in 1935, and it was there that he created the monumental body of work that secured his place as a prophet of the Space Age. He started with a work of science fiction. In 1895, he published Grezy o Zemle i Nebe (Dreams of the Earth and Sky), which describes mankind’s settlement of space, complete with characters who mine asteroids and build orbital greenhouses.
In 1903, he published a manuscript titled “The Exploration of the World Space with Jet Propulsion Instruments” in Nauchnoe Obozrenie (Scientific Review) magazine. Today this work is universally recognized as the world’s first scientifically sound proposal to use rockets for exploring space. For decades afterward the work would stun readers with the completeness and level of detail with which Tsiolkovsky designed his spaceship. The mathematical relation he formulated between the changing mass of a rocket as it burns fuel, the velocity of exhaust gases, and the rocket’s final speed has since become known as Tsiolkovsky’s formula, and is considered one of the foundations of the science of astronautics.
Amazingly, more than two decades before Robert Goddard launched the world’s first liquid-fueled rocket, Tsiolkovsky fueled his theoretical engine with a mix of liquid oxygen and liquid hydrogen, the same combination used today on the space shuttle, and still considered the most efficient of chemical rocket propellants. Tsiolkovsky arrived at the combination with little hope of testing his theory. He never attempted to build a rocket engine, let alone a spaceship. His discoveries stemmed from a thorough grounding in physics and mathematics, an awareness of the latest achievements in technology (for example, James Dewar first liquefied hydrogen in 1898), and a gift for prediction.
For all its prescient brilliance, Tsiolkovsky’s manuscript made it to print in Nauchnoe Obozrenie at a bad time, just after its publisher had died and the magazine was about to fold. “Only a few copies of the magazine were distributed before the press run was confiscated,” says Galina Sergeeva, deputy director for scientific research at the State Museum of the History of Cosmonautics, located near Tsiolkovsky’s house in Kaluga. “Until the 1960s it was believed that this work had never made it outside Russia, when, with the help of American researchers, a copy of Nauchnoe Obozrenie containing Tsiolkovsky’s article was discovered in the Library of Congress.”
Publication dates for the scientist’s early works became an issue years later when he and his followers, both in the U.S.S.R. and abroad, struggled to establish his priority in postulating key astronautical concepts. In the 1920s, Tsiolkovsky learned about the work of German space pioneer Hermann Oberth, who, working with no knowledge of Tsiolkovsky’s writing, published his key proposals for rocket-powered spaceflight in 1923. Tsiolkovsky wrote to Oberth, asserting his rights as the first to conceive of rocket flight.
“Tsiolkovsky deeply cared about his priority in the field,” says his granddaughter Elena Timoshenkova, director of the museum that has been made out of the Kaluga house. During this period, “He often published his work himself and would send it to leading scientists. However, there was almost no response.”
“He understood precisely that he was a genius, one of those people who move humanity forward,” Sergeeva adds. Ironically, it was Oberth who later helped make Tsiolkovsky’s name widely known in the West by publicizing his insights.
In 1926, Tsiolkovsky published Plan for Space Exploration, a bold 16-step program whereby human civilization could outlive its dying sun and settle the universe. The scheme called for rocket-powered airplanes, the use of plants for life support, and solar radiation to grow food and supply energy. He predicted the need for spacefarers to use pressurized suits when leaving the spacecraft, and envisioned the construction of large orbital settlements. According to Tsiolkovsky, humans would colonize the asteroid belt, the solar system, and ultimately the galaxy.
That work was followed three years later by Kosmicheskie Raketnye Poezda (The Space Rocket Trains), which advanced Tsiolkovsky’s earlier thoughts about multi-stage rockets. His calculations proved that building a rocket with separate stages, each of which would be jettisoned as it finished consuming its propellants, would allow a payload to be accelerated indefinitely through the vacuum.
Tsiolkovsky’s publications are full of ideas that would later become common practice in aerospace engineering. He proposed using graphite rudders to steer a rocket in flight, cryogenic propellants to cool combustion chambers and nozzles, and pumps to drive propellant from storage tanks into the combustion chamber. He considered human factors as well—at the dawn of the Space Age, the first cosmonauts were amazed by Tsiolkovsky’s accurate descriptions of weightlessness.