Ukraine’s Cosmonaut Hall of Fame, Part 3: Leonid Kadenyuk and the Era of Global Recognition

In our previous Hall of Fame entries, we highlighted the achievements of previous generations of Ukrainian space pioneers. Without minimizing their achievements, it should not be forgotten that they occurred during a time when Ukraine was dominated by the Soviet Union. 

The years of independence, beginning in 1991, witnessed the beginning of a completely new journey. For the first time, Ukraine found itself in the position of having to prove itself in the eyes of the global space community. But the country has risen to the challenge and, since that time, Ukraine has built numerous relationships that have resulted in several exciting projects, including the Sea Launch platform. Of particular note, however, was the important space voyage by independent Ukraine’s first cosmonaut, Leonid Kostyantynovych Kadenyuk. 

The Birth of a Dream

Leonid Kadenyuk, born in the village of Klishkivtsi in the Khotyn district of Chernivtsi Oblast, was only 10 years old when Yuri Gagarin first conquered space in 1961. The direction of the young Kadenyuk’s life was changed forever: it was at that moment that his dream of becoming a cosmonaut was born. But unlike thousands of other Ukrainian children who longed to journey into space, Kadenyuk’s stars aligned and his dreams were destined to be fulfilled. 

Upon graduating from school at the age of 16, Kadenyuk attempted to enroll in the Chernihiv Higher Military Aviation School of Pilots (ChVVAUL). Initially, however, he was rejected due to his age: at the time, admissions standards, primarily physiological, were designed for 17-year-old boys. His mother, however, came to the rescue, claiming that her son was in fact 17, a conscious deception of the Soviet system and its oppressive regulations. 

Kadenyuk eventually graduated from flight school in 1971, with a degree as a pilot-engineer and a specialization in the piloting and operation of aircraft. As a result of having established many influential connections at his alma mater, where his exceptional flying abilities were recognized, he was able to quickly take up a position at the school as a flight instructor. 

After five years at ChVVAUL, having earned an excellent reputation as a pilot, Kadenyuk decided to reach “above the sky” for the first time, participating in an All-Union program to select cosmonauts to test the “Buran” spacecraft, which was the Soviet analog of the American Space Shuttle. Out of more than 9,000 applicants representing the best of the best Soviet fighter pilots, only nine were selected.

Among them was Leonid Kadenyuk. 

After completing a year of cosmonaut training, Kadenyuk was awarded the rank of Test Pilot. He later became a Test Cosmonaut, marking the beginning of his long career as a spacecraft tester. During this period he clocked a total of 2,400 flight hours, tested 54 aircraft modifications, and piloted two spaceships: the “Soyuz-TM” freighter and the “Buran.” A passion for space was in Kadenyuk’s blood, and, thanks to his experience and skill, he soon became Ukraine’s top cosmonaut. 

As it happened, the “Buran’s” similarity to the American Space Shuttle played a key role in Kadenyuk’s eventual selection for a NASA shuttle mission. After all, up in space, having someone on board who knows “how things work in practice” is a real asset. Indeed, Kadenyuk knew every stage of the shuttle mission: by the beginning of the 1990s he already had two years of engineering and flight training as the commander of the “Buran.” Then, on one fine summer evening, when the Soviet Union simply ceased to exist, Leonid Kadenyuk turned his attention toward studying American shuttles using data from publicly available sources.

Isn’t it amazing what one person can do when guided by a dream? 

Yet, in the mid-1990s, Ukraine did not produce its own spaceships or rockets, and there was no infrastructure for launching manned space missions, so it had to rely on international partners. To the surprise of many, however, then-President Leonid Kuchma made the fateful decision to work with new partners in the West.

Training at the Kennedy Center 

Interestingly, the first discussions about Ukrainians joining an American crew in space actually happened during the Soviet period, when Leonid Kravchuk led what was then the Ukrainian Soviet Socialist Republic (SSR). However, these negotiations were ultimately placed on the back burner after independence, a result of the economic and social turmoil brought about by the transition to a market economy. 

During this period of restructuring, Ukrainian industry, including rocket manufacturing, needed international investment and contracts with global partners. One solution was the creation of the Sea Launch floating spaceport project, which included four stakeholders: Ukraine, the United States, Norway, and the Russian Federation. As part of this venture, Pivdenmash, a major industrial complex in Dnipro that produces rockets, launch vehicles, satellites, and other heavy industrial machines, was awarded numerous multi-year contracts. This investment provided a much-needed boost to Ukraine’s economy, which by the late 1990s was finally beginning to recover.

Soon, high-level discussions began to take place about the possibility of including Leonid Kadenyuk on a NASA space crew. American President Bill Clinton and Ukrainian President Leonid Kuchma even discussed the topic during telephone conversations between the two heads of state. Kuchma, who was already well-versed in aerospace technology as a result of his 20 years as a manager at Pivdenmash, proposed Kadenyuk’s candidacy himself.

Not long thereafter, Kadenyuk was indeed offered a seat on the Space Shuttle, as well as an invitation to visit the Lyndon Johnson Space Center in Texas, where he began his training as a payload and biological research specialist. During this time, Kadenyuk passed through numerous simulations used to train NASA astronauts for space missions. He was also delighted with the opportunity to get back to his favorite pastime: practicing  maneuvers in high-altitude jets like the Northrop T-38 “Talon.” For moral support, Kadenyuk temporarily relocated his family to the United States while he was at the Johnson Space Center. Still, he always emphasized that he never wanted to live anywhere but Ukraine.

Kadenyuk’s physical and practical training was supplemented by theoretical training, and he completed courses in biology, meteorology, medicine, ecology, materials science, remote geodesy and geology, and, most importantly, geobotany. It was his expertise in the latter subject that he would use during scientific experiments in orbit.

Beyond this training, it was only necessary to wait for the mission to start. 

Kadenyuk’s Mission

Space Shuttle Columbia launched its mission, designated STS-87, on November 19, 1997. 

“There was an impression of a struggle between two forces: the force of nature, represented by Earth’s gravity, which held the ship, not allowing it to break free, and the force of the human mind, represented by the power of the rocket”

(Quote from Kadenyuk interview)

The shuttle’s primary cargo was the United States Microgravity Payload (USMP-4), which contained a set of instruments containing equipment necessary for conducting various scientific procedures. These included the Confined Helium Experiment, Turbulent Gas Jet Diffusion Flames (G-744), the Isothermic Dendritic Growth Experiment, the Orbital Acceleration Research Experiment (OARE), and several special cameras for studying solar radiation and the outer shell of the International Space Station (ISS). In short, the STS-87 payload would have no problem keeping the Columbia’s crew busy!

For his part, Kadenyuk was responsible for conducting the Collaborative Ukraine Experiment (CUE), the purpose of which was to study the influence of microgravity on plant growth and reproduction in specially designed microgravity laboratories. CUE was a joint American-Ukrainian project spearheaded by Ukrainian scientists in consultation with American colleagues from Kansas State University and Louisiana State University.

The CUE experiments were meant to demonstrate how autonomous laboratories could create conditions for growing plants in space within 30 days. To achieve this, the microgravity laboratories contained several specialized modules, including the Plant Growth Facility (PGF) and specialized Biological Research in Canisters (BRIC) modules. Other nodes included the Control and Data Management Subsystem (CDMS), the Fluorescent Light Module (FLM), the Atmospheric Control Module (ACM), Plant Growth Chambers (PGC), the Support Structure Assembly (SSA), and the General External Shell (GES). A specialized Gaseous Nitrogen (GN2) Freezer was also used for certain cryogenic experiments. 

“When I wasn’t working, I always tried to take pictures and look at our Earth”

Working in the PGF and BRIC laboratories, Kadenyuk conducted a battery of ten different experiments on three types of plants: moss, turnip, and soy. These experiments investigated the effects of zero gravity on photosynthesis, changes in plant genomes, the process of fertilization and cloning of cultures, and the ability to successfully resist the pathogenic fungus Phytophthora. Notably, during one experiment a soybean plant was successfully infected. 

On a personal level, his 15-day trip completely altered Kadenyuk’s philosophy and worldview. Contemplating the growth of plants in the dark emptiness of space, he found himself reevaluating the meaning of life, ultimately returning from his journey a deeply religious man. 

In particular, the cosmonaut was surprised by the startling thinness of Earth’s atmosphere, clearly visible from the space station. From his vantage point onboard the ISS, Kadenyuk could not fathom how humanity could wage catastrophic wars and despoil the natural environment when its entire existence depended on such a thin layer of gas suspended above a tiny bubble of life moving through the endless darkness of space. 

The stars, it seems, can be poetic. 

Perhaps this was why Kadenyuk included a print edition of Ukrainian poet Taras Shevchenko’s “Kobzar” among the personal items permitted in his luggage, the first printed collection of poetry to enter Earth’s orbit. (We do not count technical manuals, as they were of more interest to Winston Scott and Takao Doi, who conducted work outside the spacecraft.)

In any case, as their mission came to an end, the crew’s return to Earth proved uneventful: after transferring to Columbia and successfully performing undocking maneuvers, they re-entered Earth’s atmosphere without issues. 

When it was all over, however, a completely different Ukrainian emerged from the Columbia than had boarded it: a man now convinced that everything in the universe has meaning. 

Kadenyuk as a Symbol of Open Partnership

Leonid Kadenyuk, ultimately, was no “mere” cosmonaut (as if there is such a thing!). In the aftermath of his short, fascinating, journey into space, he became something of a beacon for Ukraine’s space program in the first decades of independence. 

His mission contributed to Ukraine’s growing international prestige as a country that has charted its own course in space since 1991. Kadenyuk himself understood very well the significance of the 1990s for Ukrainian cosmonautics, a time of turbulence and opportunity, as well as a time of increasing openness and global recognition. It was during this era that Ukraine began establishing crucial connections on the global stage. 

Later, the seeds of cooperation planted during these years would become the foundations for the construction by “Pivdenmash” of important elements of the European VEGA and the American Antares 230 launch platforms.

Kadenyuk personally became a deeply symbolic figure in Ukraine. In 1999, for his role in strengthening international cooperation in the field of space exploration, he was awarded the title of “Hero of Ukraine.” According to a friend, he even dreamed of visiting the ISS again, possibly in a Crew Dragon or Soyuz capsule.

But this time, his dreams were not to be realized: independent Ukraine’s first cosmonaut died suddenly in January 2018 during a morning run. 

Leonid Kadenyuk, Hero of Ukraine. Not only was he the first Ukrainian cosmonaut, but he was also a reminder of Ukraine’s presence in the global space community and an ambassador of Ukrainian cosmonautics in the 1990s.