During my first business trip to Moscow in 1996 for the RAMOS program (see “RAMOS: The Russian-American Observation Satellites”), many of my colleagues and I made use of our time off to check out some of the innumerable historical and cultural sites in this great city including, naturally, Red Square. While winding our way through the line to Lenin’s Tomb, we passed along a section of the outer wall of the Kremlin lined with memorial plaques where the remains of notable Soviet citizens had been interred. While I recognized the names of a number of historical figures, one in particular caught my eye: Vladimir Mikhaylovich Komarov – the pilot of the ill-fated Soyuz 1 test flight who died when his ship crashed upon its return to Earth. Because of his sacrifice, Komarov was honored with a state funeral on April 26, 1967 just two days after his death. But what were the sequence of events which led up to what turns out to be the avoidable tragedy of Soyuz 1?

The Origins of Soyuz

The origins of the Soyuz spacecraft, including today’s updated Soyuz MS which ferries crews to the International Space Station, can be traced back to a series of design studies performed at OKB-1 (the Russian acronym for “Experimental Design Bureau – 1”) starting in December 1961 under the direction of the pioneering Soviet aerospace engineer, Chief Designer Sergei Korolev. The Soyuz complex, as it was called starting in April 1962, was a proposal for a manned circum-lunar mission with a crew of two which would be assembled and fueled in low Earth orbit using upgraded three-stage variants of the four-stage 8K78 launch vehicle which had been used to launch the first Soviet planetary probes starting in 1960 (see “The First Mars Mission Attempts”).

While the original circumlunar mission was scrapped in 1964 in favor of simpler lunar mission architectures involving only a single launch, these studies did lead to the development of a whole family of manned spacecraft based on the Soyuz 7K design for missions in Earth orbit as well as to the Moon beyond. The first version, designated 7K-OK (where OK is the Russian acronym for “orbital ship”), was officially approved for development by a Military-Industrial Commission (VPK) decree on August 18, 1965.

The standard Soyuz design consisted of three modules. At the bottom was the roughly cylindrical service module with a diameter of 2.7 meters at the base a height of 2.5 meters. It carried the spacecraft’s redundant propulsion and attitude control systems as well as other equipment needed to support the crew and their mission while in orbit. The 7K-OK service module was fitted with a pair of wing-like solar panels to recharge batteries which provided power for the spacecraft. Next was the 2.2-meter in diameter, bell-shaped descent module where the crew would ride during the mission. It was fitted with a heat shield and other recovery aids to bring the crew of up to three cosmonauts back to Earth at the end of their mission. On top of this was the roughly spherical orbital module which would provide about five cubic meters of habitable space for the crew during their mission and would be jettisoned before the return to Earth. On top of the orbital module was a probe-and-drogue type docking system but, with no provisions for an internal crew transfer at this point, the crew would need to perform an EVA to transfer to another ship with the orbital module serving as an airlock. This three-module arrangement maximizes the habitable volume of a spacecraft of a given mass and was even considered in some earlier American Apollo design proposals.

The Soyuz 7K-OK, with a launch mass of about 6,500 kilograms, would start its ascent protected by a fairing topped with a launch escape system (LES) which would pull the crew to safety in case of an abort during the first 160 seconds of the ascent. The launch vehicle for the Soyuz 7K-OK was the 11A511 which would later be known simply as “Soyuz” itself. This launch vehicle is the ancestor of the 14A14 “Soyuz-2” rocket used today. The 11A511, whose development started in 1963, was a modified version of the earlier 11A57 unified launcher which was used to orbit a number of Soviet spacecraft between 1963 and 1976 including the manned Voskhod, which gave this rocket its common name (see “The Mission of Voskhod 1”). Like the earlier Voskhod launch vehicle, the 11A511 was built to a set of strict reliability requirements known as the “3KA Regulations” so that the launch vehicle was man-rated from the start. The 11A511 with the Soyuz stacked on top was 50 meters tall and had a launch mass of 310 metric tons. With a liftoff thrust of 4,050 kilonewtons, it was capable of placing up to about seven metric tons in low Earth orbit.

Other variants of the Soyuz spacecraft that were being developed at this time included the 7K-LOK (for “lunar orbital ship”) which would be launched to the Moon along with the LK (“lunar ship”) lunar lander and other hardware on the huge N-1 rocket being developed by OKB-1 for the Soviet’s manned lunar landing mission. The service module of the 7K-LOK was significantly enlarged and the descent module’s heat shield was beefed up to handle the more punishing reentry following a return from the Moon. By the end of 1965, Korolev’s proposed 7K-L1 circum-lunar spacecraft was also approved for development. This would be a stripped-down version of the 7K-OK without an orbital module fitted with a Blok D stage borrowed from the N-1 program that could be launched on a UR-500K rocket developed and built by the rival OKB-52 design bureau. The UR-500K (which today is known as the Proton) would send the spacecraft into low Earth orbit with the Blok D stage providing the final push towards the Moon where the 7K-L1 would perform a loop around our neighbor and follow a free return trajectory back to Earth.

Preparing for Flight

The VPK decree of August 18, 1965 stated that the first pair of Soyuz 7K-OK spacecraft were to be delivered during the fourth quarter of 1965 with the first automated test flights launched during the first quarter of 1966. The first manned test flight was scheduled for the second quarter of 1966 leaving a hiatus of just over a year between the first Soyuz flight and the last Soviet crewed spaceflight of Voskhod 2 in March 1965 (see “The Mission of Voskhod 2”).

While the plans slowly evolved over the coming months, eventually it was decided that these first test flights would have the ambitious goal of performing an automated rendezvous and docking of a pair of Soyuz spacecraft. The plan was to first launch the active spacecraft followed by the passive target a day later. If the target was inserted into orbit within 20 kilometers of the active Soyuz, the latter would use its “Igla” (Russian for “needle”) rendezvous system to perform an automated docking during the first or second orbit. Otherwise, the docking would take place after 24 hours to allow the spacecraft to perform a less aggressive rendezvous profile while the spacecraft were largely out of direct contact with Soviet tracking stations. The spacecraft would remain docked for three days and return to Earth after each had spent four days in orbit.

During the first pair of manned test flights, it was planned that one cosmonaut would be launched in the active Soyuz while three would follow in the Soyuz acting as the target orbited the next day. After rendezvousing and docking, two cosmonauts from the second Soyuz would perform an EVA to transfer to the first. This would be a rehearsal for the procedure which would eventually be employed by a cosmonaut transferring between the LOK and LK during a manned lunar mission. This ambitious mission would allow the Soviet Union to catchup and (by some measures) surpass the accomplishments of the American Gemini missions (see this web site Gemini Program page). By September 1965, the first group of cosmonauts had been selected to begin training for the Soyuz program.

But as happens far too often with the introduction of any new complex spacecraft (American or Soviet), the development and production of Soyuz took far longer than planned. The situation was only made worse on January 14, 1966 when Korolev died during a botched operation to remove intestinal tumors. Following Korolev’s death, his deputy, Vasili Mishin, took control of the design bureau which was renamed TsKBEM (the Russian acronym for “Central Construction Bureau of Experimental Machine Building”) in March 1966.

By the time Mishin was formally appointed as the Chief Designer of TsKBEM in May 1966, he was planning the first manned Soyuz flights for August but once again, this deadline would also be missed. The first Soyuz flight model was not delivered for ground testing until May 12 and eventually 2,123 defects were identified. Instead of the planned one month of testing and repair, four were needed to fix the problems which were found. In the mean time, other issues were cropping up elsewhere in the Soyuz test program. For example, during a series of seven drop tests to verify the operation of the descent module’s parachute system and other recovery aids, two had failed including one on August 9 where the reserve chute failed to open due to lines being damaged by the venting of hydrogen peroxide attitude control propellant as planned during final descent. While the mix of issues differed, NASA and its contractors were also experiencing difficulties as they continued to push towards the first flight of the Block I Apollo spacecraft (see “The First Flight of the Apollo-Saturn IB“).

But as work towards getting the first unmanned test flights of the Soyuz off the ground proceeded during the autumn of 1966, Soviet authorities finalized the crew selection for the upcoming Soyuz 1 and 2 missions. The commander for Soyuz 1 would be the forty year old Vladimir Komarov. Komarov was a pilot in the Soviet Air Force before being selected to be part of the first group of Soviet cosmonauts in March 1960 and had previously flown as the commander of the three-man Voskhod 1 mission in October 1964 (see “The Mission of Voskhod 1”). He would be the first Soviet cosmonaut to fly into space twice. Komarov’s backup was the world’s first person to fly into space, the 33-year old Yuri Gagarin who had just been returned to flight status to participate in the Soyuz program.

The commander of the crew of Soyuz 2 was veteran cosmonaut Valery Bykovsky. Chosen as part of the first cosmonaut group like Komarov and Gagarin, Bykovsky at age 32 years had previously flown on the Vostok 5 mission in June 1963. His backup was the 37-year old Andrian Nikolayev who had previously flown on the Vostok 3 mission. The flight engineer on Soyuz 2 was the 32-year old rookie Alexei Yeliseyev who had just joined the cosmonaut corps in May 1966. His backup was the 32-year old Valery Kubasov who had just joined the cosmonaut corps with Yeliseyev. The last member of the Soyuz 2 prime crew was Yevgeny Khrunov. The 33-year old Khrunov was designated as the research engineer for the mission and had served as a military pilot before being selected as part of the first group of cosmonauts. While he had served as the backup pilot for the Voskhod 2 mission of March 1965 (see “The Mission of Voskhod 2”), this would be his first space flight. Khrunov’s backup was the 32-year old Viktor Gorbatko who had been part of the original cosmonaut group and had previously served as the backup commander of the Voskhod 2 mission. It would be Yeliseyev and Khrunov who would perform the first two-person EVA to transfer from Soyuz 2 to Soyuz 1 after the two spacecraft had docked. As the first unmanned Soyuz test flight was prepared for launch, it was hoped that the first manned missions could fly in December 1966.

The Unmanned Test Flights

As the crews for the Soyuz 1 and 2 missions continued their training, final preparations were being made to launch the first pair of Soyuz spacecraft on an automated test flight. Finally on November 28, 1966 at 16:00 Moscow Time, 11A511 serial number U150002 lifted off from Launch Complex 31 at the Baikonur Cosmodrome in Soviet Kazakhstan carrying the 6,386-kilogram 7K-OK No. 2 (with the “active” 7K-OK spacecraft receiving even serial numbers while the “passive” targets received odd ones). After the Blok I final stage of the launch vehicle had shut down almost nine minutes later, what was now called Kosmos 133 was in a 181 by 232 kilometer orbit with an inclination of 51.9°. While a slight underperformance of the first 11A511 ever launched had left the first Soyuz in a slightly lower than planned orbit, it was still sufficient to carry on the mission.

Unfortunately, other issues with the new spacecraft threatened the mission. Within two minutes of separating from its launch vehicle, the pressure in the propellant tanks of the DPO approach and orientation system used for attitude control had dropped from 340 to 38 atmospheres. Over the next quarter hour, the engines had continued firing and finally depleted the system’s propellant supply leaving the spacecraft rolling at a rate of two RPM. With no means of maintaining attitude during rendezvous, the launch of 7K-OK No. 1 on November 29 was cancelled as all efforts turned towards getting Kosmos 133 safely home before its orbit decayed after about 39 circuits around the globe.

Attempts to regain attitude control of the Kosmos 133 using the stabilizing thrusters of its DKD backup deorbit propulsion system failed when the spacecraft turned in the direction opposite of what was commanded due to a previously undetected design flaw. Ultimately, engineers solved the problem of deorbiting Kosmos 133 by alternating between 10 to 15 second bursts of the SKD main engine with use of the independent set of small DO thrusters used for fine attitude control. While less accurate, it would be enough to bring the spacecraft back to Earth after a series of several bursts.

The first attempt to bring Kosmos 133 during the 17th orbit using solar attitude sensors failed. Attempts to bring the spacecraft back during the following two orbits using ion attitude sensors also failed. On the morning of November 30, ground controllers once again attempted to deorbit the spacecraft over Soviet territory. After a deorbit burn which was cut short during the 33rd orbit, a fifth and final series of engine firings on the next orbit finally succeeded in bringing the wayward spacecraft down. Unfortunately the trajectory was flatter than desired so that the descent module of Kosmos 133 came down far downrange east of the Mariana Islands in the Pacific. A 23-kilogram self-destruct charge destroyed the descending capsule after 45 hours and 21 minutes of flight.

While the first test flight of the Soyuz failed to meet its objectives, it did give engineers a chance to test the various systems of their new complicated spacecraft and gained valuable experience. As the engineers from TsKBEM and their associated design bureaus corrected the new issues uncovered by the Kosmos 133 flight, preparations were underway for a second unmanned test flight. To simplify the flight, it was decided that the next mission using 7K-OK No. 1 would be a solo mission launched on December 14, 1966 with no attempt at an automated docking with a second spacecraft. If successful, the pair of manned Soyuz flights were scheduled for launch on January 29, 1967 – less than a month before the scheduled launch of NASA’s first manned Apollo mission (see “The Future That Never Came: The Unflown Mission of Apollo 1”).

At 16:00 Moscow Time on December 14, 1966, the four boosters of 11A511 serial number U150002 ignited at Launch Complex 31 but then quickly shutdown as automatic systems detected a problem with the core’s RD-108 engine. After the rocket had been powered down, ground crews returned to the launch pad to safe the rocket. Unfortunately the Soyuz systems had not been properly powered down and without warning, the LES was inadvertently activated pulling the unoccupied descent module clear of the launch pad. The activation of the LES ignited coolant gushing out of the Soyuz service module which remained behind starting a fire at the top of the stack which quickly engulfed the rocket on the pad forcing an evacuation. Within two minutes, the rocket blew up destroying Launch Complex 31 (only one of two launch pads configured to launch the Soyuz) while seriously injuring several members of the ground crew and killing one.

While the launch pad at Site 1 (where all previous Soviet crewed spaceflights had been launched) was being upgraded to support a pair of successive Soyuz launches, 7K-OK No. 3 was modified to fly an unmanned solo test flight in late January 1967 with a manned flight now scheduled to follow in March. Delays in preparations pushed the official launch date out to February 6 while a minor short circuit in the 7K-OK orbital module scrubbed the first launch attempt forcing a one day postponement. After a twenty-minute delay, at 6:20 Moscow Time on February 7, what would become known as Kosmos 140 finally lifted off from the Baikonur Cosmodrome.

Once again, an underperformance in the new 11A511 launch vehicle left the Soyuz in a lower than expected orbit of 170 by 235 kilometer orbit. While everything on the spacecraft seemed to be going as planned, by the fourth orbit trouble appeared when the attitude control propellant levels had dropped to half due to a malfunction in the astro-orientation system. An engine burn during the fifth orbit to gain some altitude failed leaving Kosmos 140 in path which would decay after 48 orbits. The failure of the astro-orientation system also prevented the spacecraft from stabilize its solar panels to point towards the Sun to recharge its batteries.

On the 22nd orbit, the main engine was fired for 48 seconds to raise the altitude of Kosmos 140 but subsequent attempts to reorient the spacecraft towards the Sun finally exhausted the attitude control propellant supply. Before the batteries were depleted, it was decided to bring Kosmos 140 home early on February 9 using the ion orientation sensor successfully tested on Kosmos 133 to provide attitude information during the deorbit burn. With the burn successfully completed, Kosmos 140 began its descent back towards Soviet territory.

After emerging from the normal reentry communications blackout, contact with the descent module of Kosmos 140 was lost shortly after it deployed its parachute. Kosmos 140 landed out of touch with ground controllers after a flight of 47 hours and 32 minutes. Following a four-hour search, Kosmos 140 was found to have come down 510 kilometer short of its intended landing zone because it had flown an unplanned ballistic reentry profile. Unfortunately, the descent module had landed on the ice-cover Aral Sea and subsequently sank in ten meters of water. After much effort by recovery teams, an Mi-6 helicopter was eventually used to drag the descent module three kilometers underwater to dry land two days after landing. It was then discovered that a three by one centimeter hole had been burned clean through the heat shield which caused the module to sink upon its unplanned splashdown and would have surely killed any crew on board. It was later found that a maintenance plug had been improperly sealed resulting in the failure.

The Soyuz 1 Mission

The prudent course of action at this point would have been to fly another unmanned test flight before committing to crewed missions of the 7K-OK. But as engineers looked into the causes of and remedies for the various system failures during the Kosmos 140 mission, pressure was building on multiple fronts to get the manned Soyuz test flights off of the ground sooner rather than later. There was pressure from leaders in the Kremlin for another space spectacular to be used for propaganda purposes during a number of upcoming anniversaries. There was pressure from inside TsKBEM to end the two year long hiatus of crewed spaceflights and start proceeding with Soyuz flights in part to get back into the race to the Moon but also to fend off rival design bureaus with their own ideas on how to reach the Moon.

Especially after the Apollo 1 fire of January 27, 1967 had effectively forced a halt to the Apollo program, there were those who thought that the dual Soyuz manned mission with a crew exchange following docking would provide the Soviet Union with the opportunity to surge ahead of the US in the race to the Moon not to mention eclipse the accomplishments of NASA’s ten manned Gemini missions with one space spectacular. While the issue with the heat shield was felt to be easily remedied, there were those who argued that the issues resulting from automatic systems failures during the Kosmos 140 mission could have been avoided by a pilot on board to take manual control when needed. While there are stories about the reluctance of the cosmonaut team to fly Soyuz before there was a successful automated test flight, there is also evidence that they too were anxious to get back into space. While in retrospect, another unmanned Soyuz test flight would have been the prudent choice, the decision was made to proceed with the complex two-ship manned test flight instead.

On April 14, 1967 the State Commission charged with overseeing the Soyuz mission met and approved the start of final preparations for the first manned mission launch tentatively set for April 23. The next day, the spacecraft destined to become “Soyuz 1”, 7K-OK No. 4, was transferred to the fueling facility at Area 31 followed by its intended target vehicle, 7K-OK No. 5, two days later. On April 20, the State Commission met again to review preparations for the dual launch and officially confirmed the crew for the upcoming launches. Right on schedule at 7:00 local time on April 21, 7K-OK No. 4 and its launch vehicle were rolled out of the assembly building as work to enclose 7K-OK No. 5 in its fairing started. With the first Soyuz erected on Pad 1, integration test began at 13:00 local time.

After a final meeting with Mishin on April 22 culminating with traditional prelaunch cermonies, Komarov started his last sleep period in the middle of the day in preparation for his early morning launch as did a number of officials charged with overseeing the mission. At 23:30 Moscow Time, the State Commission met for a launch meeting where, after reviewing the state of preparations, they gave the final approval to fuel the Soyuz launch vehicle. Gagarin accompanied Komarov on the bus ride to the launch pad in the early morning hours of April 23 and boarded the waiting Soyuz. With the completion of propellant loading at 3:00 Moscow Time, all was ready for the first manned Soyuz launch.

At 3:35 Moscow Time on April 23, 1967, Soyuz 1 successfully lifted off from Pad 1 at the Baikonur Cosmodrome right on schedule. After almost nine minutes of powered flight, the 6,450-kilogram Soyuz 1 had been placed into a 196 by 225 kilometer orbit with an inclination of 51.7°. Almost immediately, work began at Pad 1 to get what would be Soyuz 2 prepared for launch during a 50-second window starting at 3:10 Moscow Time the next day.

While work proceeded for the launch of the Soyuz 2 target vehicle, all was not going well in orbit. One of the solar panels on Soyuz 1 along with an associated backup telemetry antenna failed to deploy. In addition, problems cropped up once again with the astro-orientation system. These issues conspired to make it very difficult to orient the spacecraft and impossible to set it into a stabilizing slow spin to keep the solar panels pointing towards the Sun. Some sources state that Komarov even knocked hard on the side of the spacecraft in an attempt to free the stuck solar panel.

By the second orbit, Komarov had entered the spacious orbital module and commented on the view out its windows. He noted that the short wave communication system was not operating and only 13 to 14 amps of current were being generated by the sole deployed solar wing – only half of what was required to keep Soyuz going. Calculations by ground controllers indicated that without more power, Soyuz 1 would be forced to return after only a day in orbit before its batteries were depleted.

On the third orbit, Komarov attempted to manually orient his spacecraft without success. Another attempt on the fifth orbit using the ion sensor orientation system, which was having issues operating properly during the night side passes, also failed. With Soyuz 1 expected to be out of range of Soviet tracking stations from the 7th to 13th orbits, Komarov was instructed to begin his first sleep period in orbit as engineers back on the ground considered their options. Preparations for the launch of Soyuz 2 would continue with a final decision about whether or not to launch to be made after communications with Soyuz 1 had been reestablished.

Coming Home

During the 13th orbit late in the day on April 23,the rotation of the Earth had brough the ground track of Soyuz 1 back into range of Soviet tracking stations once again. Komarov reported that he had attempted to orient his ship anew but with no success. Both of the attitude sensor systems were not working properly leaving Komarov to manually orient his craft using visual sightings through his spacecraft’s VSK periscope. With no resolution to the issues forthcoming, the launch of Soyuz 2 was cancelled and the decision was made to bring Komarov home between the 17th and 19th orbits during the mission’s second day.

As Soyuz 1 came back into range during the 17th orbit, Komarov reported that he could not orient his ship properly for firing the SKDU engine for return home. Ground controllers decided on a backup orientation procedure for another attempt on the 19th orbit. After this, the batteries on Komarov’s spacecraft would be exhausted leaving just a backup system which would be good for three orbits at best. During the 18th orbit, Gagarin, who had flown to the tracking station in the Crimea after Komarov’s launch, radioed the final instructions for the retrograde burn which would bring Komarov home. Using a new procedure for which he had not trained, Komarov would manually orient Soyuz 1 using the Earth as viewed through the VSK periscope then employ the craft’s reliable gyro system to maintain attitude until the engine was fired.

With quickly dwindling options and employing all of his piloting skills, Komarov successfully oriented Soyuz 1 using the untried procedure and fired its SKDU engine for 146 seconds starting at 5:57:15 Moscow Time on April 24. Because of the asymmetry of the Soyuz with only a single solar panel deployed, the spacecraft’s attitude deviated during the braking maneuver decreasing its effectiveness. However, tracking quickly revealed that Soyuz was on its way back home via a ballistic reentry that would come down in the reserve landing zone 65 kilometers east of Orsk at about 6:24 Moscow Time. After separation of the service module with its various antennas, communications was only possible after a VHF antenna was deployed from the descent module after the parachute opened for final descent.

At 6:22 Moscow Time, the Soyuz 1 descent module was detected on radar. Unknown to ground controllers or recovery crews who were racing towards the landing zone, the main parachute on the descent module had failed to deploy properly. Out of touch with ground controllers, Komarov then manually released the reserve parachute but it also failed to deploy properly as its lines became fouled with those of the main chute. The Soyuz descent module crashed into the ground at a speed of about 200 kilometers per hour killing Komarov instantly. The Space Age had experienced in first in-flight fatality. Recovery crews, who had seen a flash in the distance thinking that the descent module’s braking rockets had fired, landed their helicopter about 100 meters from the crash site with the descent module engulfed in smoke and flames. As they put out the fire and attempted a rescue, it quickly became apparent that the spacecraft and its pilot were a loss.

Komarov’s remains were accompanied by the prime and backup crews of what would have been Soyuz 2 and arrived in Moscow after midnight on April 25. Following an official autopsy, Komarov’s remains were cremated and his urn placed in the Central House of the Soviet Army for mourners to pay their respects. On April 26, Komarov was given a state funeral with full military honors culminating with his internment in the Kremlin beside other heroes of the Soviet Union. But as the world mourned the loss of Komarov, the investigation began into what had caused the failure of Soyuz 1. Now both the Apollo and Soyuz programs were at a halt as the two space superpowers tried to recover from their respective losses of the crews of Apollo 1 and Soyuz 1.

Follow Drew Ex Machina on Facebook.

Related Reading

“The Future That Never Came: The Unflown Mission of Apollo 1”, Drew Ex Machina, January 27, 2017 [Post]

General References

Phillip Clark, The Soviet Manned Space Program, Orion Books, 1988

Rex D. Hall and David J. Shayler, Soyuz: A Universal Spacecaft, Springer-Praxis, 2003

Asif A. Siddiqi, The Soviet Space Race With Apollo, University Press of Florida, 2003