The Baikonur Cosmodrome in southern Kazakhstan is one of the busiest and the most important spaceport on earth with over a thousand satellite launches under its belt and more than one hundred fifty launches with human crews. As the oldest spaceport, Baikonur Cosmodrome is steeped in history, being behind many milestone space missions, like the launch of the first artificial satellite Sputnik 1 in 1957, the first spacecraft (Luna 1) to reach the moon in 1959, the first human in the space, Yuri Gagarin, in 1961, and the first woman in space, Valentina Tereshkova, in 1963. Understandably, the Baikonur Cosmodrome have had its share of disappointments and disasters, the most notable among which is the so-called Nedelin catastrophe, which remains the deadliest space exploration related disaster in history.
The space race between the Soviet Union and the United States started with the development of missiles, especially ones that could fly over oceans and continents to deliver nuclear warheads on demand. In 1959, the Soviet Union test fired the first successful ICBM (Intercontinental Ballistic Missile), the R-7, developed by rocket engineer Sergei Korolyov. The R-7 would go on to become one of the most successful rockets in history. It was used to place Sputnik in orbit and Yuri Gagarin in space. A heavily modernized version of the R-7 is still used as the launch vehicle for the Russian Soyuz spacecraft.
The trouble with early Soviet missiles was the use of liquid oxygen as the oxidizer for the fuel. Liquid oxygen necessitated cryogenic refrigeration and posed difficulties in long-term storage, essential for missiles on standby for rapid deployment. Additionally, the Soviets wanted a system with better guidance, and an infrastructure that was less vulnerable to surveillance from aerial and satellite reconnaissance.
To address these issues, the Soviet leadership initiated the development of a new type of missile that used so-called “storable” propellants, with improved navigation and smaller mobile launch platforms. The propellants chosen for this new missile, designated the R-16, were unsymmetrical di-methyl hydrazine (UDMH) as a fuel and inhibited red fuming nitric acid (IFRNA) as the oxidizer. These propellants were hypergolic, meaning they spontaneously ignited upon contact, eliminating the need for external ignition sources.
Both the fuel and oxidizer have high boiling points compared to other rocket fuels (such as liquid hydrogen) and oxidizers (such as liquid oxygen), that allowed rockets to remain fueled and ready for launch over extended durations without the risk of the fuel or oxidizer evaporating and requiring replenishment. With these new type of fuels, a missile could be rolled out of the hangars, fueled and readied for launch within three hours. The downside was that both UDMH and nitric acid are extremely corrosive and toxic. They were so dangerous that Soviet engineers called them “devil’s venom.”
The R-16 missile was developed by Mikhail Yangel, and heading the missile development program was Chief marshal of Artillery Mitrofan Ivanovich Nedelin. Together, the two men were determined to have a successful test launch by October 1960 as an early gift to Nikita Khrushchev, the Soviet premier, in celebration of the upcoming 43rd anniversary of the Bolshevik Revolution. To meet the deadline, the design and development of the missile was rushed, including its flight-development test program. Veterans of the test range would later testify that the rocket was plagued with problems since the day its testing commenced in Tyuratam on September 26, 1960.
Mitrofan Ivanovich Nedelin
On the morning of October 21st, the new R-16 rocket was rolled out to the pad at Tyuratam. The initial checks at the launch pad were apparently uneventful and were completed successfully by October 23. On the same day the missile was fueled for launch. By the time of the fueling, by protocol, all unessential personnel was supposed to leave the area, but Marshall Nedelin and Mikhail Yangel ignored the safety rules and stayed at the pad. Nedelin reportedly set up a chair on the pad to observe and direct operations. Around 150 other nonessential people, including military and civilian, also remained on the pad.
Shortly after the fueling process was finished, the rocket developed a fuel leak. However, this leak was considered tolerable, as long as it did not worsen, and preparations for the launch continued. According to certain accounts, there were requests to drain the fuel and remove the rocket from the launch pad, but Nedelin rejected these suggestions, saying that there would be "no time for such things in a nuclear war." At this juncture, the tests had already reached a point of no return, as once the rocket was fueled, there was no procedure in place to drain the propellant from the vehicle. Consequently, the launch team had no alternative but to proceed or abort the mission. The latter was not possible as it would delay the launch by at least a month, destroying any chance of meeting their mandatory launch schedule.
The following day, October 24th, was the day of launch. Several high government officials had arrived to view the launch, and a viewing stand was set up for them 800 meters from the pad. Nedelin was under tremendous pressure from Moscow to launch on time, and when another delay of 30 minutes was announced Nedelin insisted on going back to the pad himself to figure out what's going on. Meanwhile, mounting technical problems and lack of time were pushing the technicians to the wall. The presence of Nedelin on the launch pad would have put even more pressure on the technicians, thereby compromising the safety at the pad.
At approximately 18:45 hours, about 30 minutes before the scheduled launch, a technician turned off a switch called PTR (or Programming Current Distributor) which activated the systems onboard the rocket in a certain sequence. When the operator turned the switch to neutral, the switch momentarily moved through an operational position that sent a spurious signal to open the propellant line valves of the second-stage engines. Upon mixing, the propellants self-ignited and the engines came to life, with an estimated 250 unsuspecting people still around the rocket.
Instantly, the roaring flame of the engine burst through the fuel tank of the first stage directly below, initiating an enormous explosion of the fully-fueled rocket. In seconds, a giant fireball, up to 120 meters in diameter engulfed the launch pad.
Many people were killed instantly, while many others burned and fell off the pad, still in flames, attempting to escape the blaze. A video camera that had been set up to record the launch captured these terrible moments instead.
Roscosmos engineer Boris Chertok describes the incident in Rockets and People:
The enormous temperature at a significant distance from the epicenter of the fire burned peoples’ clothing, and many of those fleeing who got bogged down in molten asphalt burned up completely.
[...]
Running for their lives, they found themselves in the ditch surrounding the launch site or on sand; instead of throwing off their flaming clothes or falling to the ground to extinguish the flames, like burning torches, they attempted to flee farther from the launch site and got tangled in the barbed wire surrounding it. Rescue workers arriving on the scene attempted to help the people who had run to them. They flung them to the ground and threw sand on them. It was 2 hours before the fire fighters managed to contain the fire and the launch site became accessible to the rescue workers.
Another eyewitness describes the horrific scene:
At the moment of the explosion I was about 30 meters from the base of the rocket. A thick stream of fire unexpectedly burst forth, covering everyone around. Part of the military contingent and testers instinctively tried to flee from the danger zone, people ran to the side of the other pad, toward the bunker...but on this route was a strip of new-laid tar, which immediately melted. Many got stuck in the hot sticky mass and became victims of the fire...The most terrible fate befell those located on the upper levels of the gantry: the people were wrapped in fire and burst into flame like candles blazing in mid-air. The temperature at the center of the fire was about 3,000 degrees. Those who had run away tried while moving to tear off their burning clothing, their coats and overalls. Alas, many did not succeed in doing this.
Chief Marshal Nedelin perished in the flames (he was reportedly only 15 meters away from the rocket when it exploded), but missile designer Mikhail Yangel survived only because he had left to smoke a cigarette behind a bunker a few hundred meters away. Later, an enraged Khrushchev rebuked Yangel, asking him ”why are you still alive?”, to which Yangel reportedly answered in a trembling voice, “Walked away for a smoke. It's all my fault.”
At least seventy-four people died that day and approximately fifty more died later of their injuries. Details of the disaster remained a secret for nearly three decades. Nedelin's death was officially listed as having occurred in a plane crash. Details about the disaster did not become public until 1989 when the Soviet Union acknowledged the events.
Exactly three years after the disaster at Tyuratam, on October 24, 1963, another fatal accident at the launch pad resulted in the death of 7 people. Since then, October 24 is regarded as the Black Day at Baikonur Cosmodrome, and no launches take place on this day.
Today, the site of the explosion at Site 41 lies as a desolate, forsaken parcel on the outskirts of the Baikonur Cosmodrome. Here, one can find a modest memorial bearing the names of the individuals who lost their lives and a map illustrating the layout of the old launch complex. In another part of the base, there stands a solitary casket, which holds the remains of those individuals who could not be identified. This casket was interred in Leninsk Park and now rests beneath a gentle rise of grass, encircled by a small enclosure.
The memorial at the site of the disaster. Photo credit: Mixrunya/Wikimedia Commons
References:
# Boris Chertok, Rockets and People, Volume 2: Creating a Rocket Industry
# System Failure Case Studies, NASA
# Nedelin disaster, Russian Space Web
# Nedelin disaster, Aerospaceweb
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