At the same time American agencies like NACA and the USAF were studying manned spaceflight through the 1950s (see “The Origins of NASA’s Mercury Program”), comparable efforts were quietly taking place independently in the Soviet Union. As with virtually every other aspect of the Soviet Union’s early space program, Chief Designer Sergei P. Korolev and his OKB-1 (Experimental Design Bureau No. 1) lead the way. All during the 1950s when Korolev and his colleague, Mikhail K. Tikhonravov of NII-4 (Scientific Research Institute No. 4), were pushing their original Earth satellite proposal, it also included plans to send probes to the Moon and men into orbit. When the satellite proposal was finally adopted by the Soviet government on January 30, 1956, the lunar probe and manned satellite projects were also given the green light.
Portrait of Chief Designer Sergei Korolev who led OKB-1 which was responsible for Sputnik and other early Soviet achievements in space. (RKK Energia)
Initially the bulk of the resources at OKB-1 were poured into building Object D (which would eventually become Sputnik 3 – see “Sputnik 3: The First Orbiting Geophysical Laboratory”) as well as continuing development of the R-7 as both an ICBM and the basis of a launch vehicle. Work on more advanced space missions did not begin until after November of 1956 when Tikhonravov and his group were officially transferred from NII-4 to Korolev’s OKB-1 to become Project Department No. 9. On March 8, 1957 the group was reorganized to focus exclusively on the planning and development of spacecraft. Within a month the group released their first preliminary plan for lunar and manned spaceflights.
This Russian diagram shows the configuration of the Object D satellite as it was flown. Click on image to enlarge. (RKK Energia)
As these efforts began, Korolev envisioned the need for short suborbital manned flights comparable to the existing program to launch dogs on high altitude ballistic flights using “geophysical” rockets developed at OKB-1 like the R-2A and R-5A. At this time manned missions into orbit were not anticipated until the 1964 to 1967 time frame. But the launches of Sputnik 1 and 2 in October and November of 1957 changed everything (see “Sputnik 1: The Launch of the Space Age”).
The first Sputnik launches were to affect the manned space program in several ways. The impact the launch of Sputnik 1 had on the West led Soviet Primer Nikita Khrushchev to exploit space missions for their propaganda value. Development of more advanced and spectacular missions like the manned satellite program were immediately approved and placed on the fast track. Also at the insistence of Khrushchev, Sputnik 2 was launched with a dog on board. While thermal control problems marred the mission, it did demonstrate that weightlessness would not be a major hazard for a human (see “Sputnik 2: The First Animal in Orbit”). As a result, Korolev scrapped his initial, more conservative approach and moved ahead with a much more aggressive plan. In December of 1957 Korolev established three new design groups under Tikhonravov: The first group would design automatic lunar probes, another group communication satellites and the last would work on piloted spacecraft using the designs of the successors of Object D as a starting point.
Moving Towards a Manned Satellite
As work was moving forward during 1956 and 1957 on Object D, a group at Department No. 9 under Eugeniy F. Ryazanov was already performing preliminary studies on a series of successors designated Object OD (with “OD” standing for “Oriented D”). Unlike Object D whose orientation was not controlled, Object OD would be equipped with an attitude control system to point its payload of photo-reconnaissance cameras. Object OD-1 would use a lightweight, passive attitude control system and be equipped with a cone-shaped reentry module to return its payload of exposed film. Unfortunately early studies quickly showed that the mass of Object OD-1 would exceed the 1,400 kilogram payload capability of the R-7-based 8A91 being developed to launch Object D. A more powerful rocket would be needed.
Soviet cutaway drawing of the R-7A ICBM also known as the 8K74. It would serve as the basis of more advanced R-7-based launch vehicles. Click on image to enlarge. (RKK Energia)
Based on experience with the 8K71 ICBM as well as the 8K71PS and 8A91 satellite launch vehicle versions of the R-7, development of an improved ICBM called the R-7A (also known by the designation 8K74) was begun. Many of the R-7A upgrades could be incorporated into a new family of satellite launch vehicles to increase their reliability and payload performance. One of the designs to result from these studies was the 8A92. Like the 8A91, the 8A92 was initially envisioned as a two-stage launch vehicle consisting of four strap on boosters surrounding a sustainer core. Its increased performance promised to orbit a payload of as much as 1,700 kilograms. But even this enhanced lift capability would prove to be insufficient. By the end of 1957, the Object OD-1 design was still 400 kilograms overweight.
With continuing development problems and the change in goals in December of 1957, work on Object OD-1 was ended. Resources were instead shifted to the development of the larger and more advanced Object OD-2. In its reconnaissance configuration, this spacecraft retained the basic cone-shaped reentry module of Object OD-1 but it was now mated to a large cylindrical service module containing an active attitude control and other support systems not required for the return to Earth.
The estimated 4,900 kilogram mass of Object OD-2 required the development of a larger launch vehicle called the 8A93. The 8A93 would be a three-stage rocket using a stripped down R-7A for the first two stages and a third stage based on the Blok E being developed for the 8K73 Moon rocket (see “The First Moon Race: Getting off the Ground”). With a third stage built around the powerful RD-109 engine being developed by OKB-456 under Valentin P. Glushko, this much more powerful rocket promised to deliver a payload as great as 5,300 kilogram into orbit.
A Manned Spacecraft Design
Portrait of the chief participants at Project Department No. 9 of OKB-1 under Konstantin P. Feoktistov who were assigned the task of designing a manned spacecraft. (RKK Energia).
A team of engineers from Project Department No. 9 under Konstantin P. Feoktistov were assigned the task of designing a manned version of Object OD-2. While this team retained the original concept of employing separate service and reentry modules to minimize the total spacecraft mass, they ultimately designed a spacecraft totally different from the original OD-2 concept. As would be the case with its sister the 8K73, this team anticipated that the development of the Blok E stage of the 8A93 would drag on far longer than anticipated. Instead they opted to use the 8K72K. Based on the 8K72 launch vehicle then under development to launch the E-1 lunar probes, the 8K72K would incorporate a number of modifications to improve its performance and reliability. This included an improved Blok E third stage that replaced the RO-5 engine used in the 8K72 with an upgraded RO-7 being developed by OKB-154 under Semyin A. Kosberg. For later flights, the original two-stage 8A92 concept would be upgraded to include an improved Blok E stage. The orbital payload of the 8K72K and 8A92 would be no more than 4,700 kilograms but it was felt that these rockets would be available at a sooner date than the more powerful 8A93.
Diagram showing the 8K72 launch vehicle equipped with a Blok E stage on the right. It would serve as the basis for the improved 8K72K to be used to launch Vostok. Click on image to enlarge. (RKK Energia)
Presented with more stringent payload limits, Feoktistov’s team had to make every effort to minimize the mass of the manned OD-2. While a variety of shapes for the reentry module were considered, the original conical shape was ultimately abandoned in favor of a 2.4-meter in diameter sphere with a conical service module on the top. The simple spherical shape had many advantages for reentry. First the aerodynamics of a sphere were well understood and it promised to be stable. This shape also maximized the interior volume for the passenger and critical recovery systems while at the same time minimizing the mass of the required heat shielding. By offsetting its center of mass from its center of figure, the reentry module would automatically keep itself oriented during its return to Earth without the mass penalty of an active attitude control system. This approach did result in a more punishing ballistic reentry but peak braking loads would still be limited to a tolerable 10 Gs. This design also promised to keep the landing target errors to an acceptable 200 to 300 kilometers. While a lightweight, unpressurized service module was studied, ultimately Korolev’s wish to use a pressurized one was adopted despite the weight penalty. This helped to simplify thermal control problems, offered a more benign environment for the onboard systems and would speed development.
Diagrams showing two concepts for Object OD-2. The design in the top panel dates from August 1958 while the design in the lower panel is from early 1959. Click on image to enlarge. (Nauka)
The final hurdle to a successful manned mission was the landing. American efforts centered on a parachute-assisted water landing that would take advantage of their large naval surface fleet. Soviet designers opted for a touchdown on land to take advantage of the Soviet Union’s vast territory. A variety of systems including a helicopter-like rotor favored by Korolev were considered for the final braking but ultimately it was decided to use a simple a parachute. Unfortunately a parachute large enough to guarantee a survivable landing for the passenger-laden reentry module would be prohibitively heavy. In April of 1958 Feoktistov’s design team came up with an ingenious solution which they called “the forced landing procedure”. The cosmonaut would ride inside the reentry module until after the worse of the reentry was completed. At an altitude of 7 kilometers the cosmonaut would use an ejection seat to blast clear and make a final descent using his own parachute. The descending reentry module would then be free to make a rough landing at a final speed of 10 meters per second using a comparatively small parachute. This ejection seat could also double as a launch escape system to pull the cosmonaut clear of his craft in case of a catastrophic failure during ascent.
Soviet diagram illustrating the “forced landing” procedure. Click on image to enlarge. (RKK Energia)
Feoktistov’s team was also able to use the same design to meet the military’s reconnaissance needs. In this second version of the OD-2, all the systems needed to support a passenger were replaced with a photo-reconnaissance package and associated systems. This approach only made sense since both manned and reconnaissance orbital missions involved the return of a payload from orbit. This new Object OD-2 proposal was presented to Korolev in June of 1958. He approved the manned design and the cone-shaped reconnaissance configuration of the OD-2 was eventually dropped in favor of Feokstitov’s unified spacecraft design concept. But while Korolev was convinced that this was the best way to proceed, he still had powerful critics that needed to be swayed.
Seeking Approval
At this time there was much debate among the various Chief Designers and officials in the Soviet government on which path their space program should take. Echoing concerns that are still voiced today, one group insisted that manned spaceflight was too expensive and would yield few if any tangible benefits. They felt that the country’s limited resources were better spent on the development of unmanned spacecraft to perform various useful tasks. While a valid argument could be made on this point, Khrushchev clearly preferred a manned flight for its potential propaganda value. In addition, because of the amount of hardware shared between the manned and unmanned reconnaissance versions of Object OD-2 that Feoktistov group had designed, development efforts for a manned spacecraft could have direct applications towards a highly useful photo-reconnaissance satellite.
Others thought that suborbital flights should be a prerequisite for a full blown manned orbital flight. But by May of 1958 even Korolev had become convinced that manned suborbital flights, even suborbital test flights, were superfluous. This was in part due to the relative success of Sputnik 2 and a continuing series of canine suborbital test flights. Korolev also argued that the development of hardware needed for a manned suborbital flight would not add as much to the art as an orbital mission would. This despite the small additional effort required to achieve the latter. In the end Korolev had decided that a manned suborbital flight would be a meaningless stunt. He felt that moving directly to the development of a manned satellite would be of much greater value given the growing competition with the United States and the resources he had available.
In the end Korolev won the argument and the Council of Chief Designers approved his plan for a manned orbital spaceflight in November of 1958. Work to design and manufacture this new spacecraft began in earnest in early 1959 as the Soviet government issued a series of decrees on the matter. By the summer of that year the spacecraft officially received the name the world would know it by: Vostok.
Finalizing Vostok’s Design
As a result of significant changes made to the constantly evolving Object OD-2 design during the opening months of 1959, the eventual Vostok design was now designated Object K with the “K” standing for “korabl” (Russian for “ship”). As with its predecessor, Object K would consist of two modules. The descent module was a sphere 2.3 meters in diameter with a mass of about 2,400 kilograms. It was covered with an ablative heat shield and contained all the equipment needed for returning from orbit. It was designed to carry a single space suit-clad cosmonaut in a semi reclined ejection seat which served a dual purpose: During the early phases of ascent, this seat could safely eject the cosmonaut away from the craft in case of a problem. Because of weight restrictions, the capsule could not carry a large enough parachute to guarantee a soft enough landing for the pilot at the end of a normal mission. Instead a forced landing procedure was developed where, after reentry was done, the cosmonaut ejected from the descent module at an altitude of 7 kilometers. He then used his own parachute to make a soft landing separate from the more quickly falling descent module.
A Soviet cutaway diagram of the Object 3K spacecraft. Click on image to enlarge. (RKK Energia)
During the flight, the cabin interior maintained an oxygen-nitrogen atmosphere at a pressure of one bar like on the ground. Since the effects of weightlessness were unknown, the spacecraft was completely automated with the “pilot” only taking control using rudimentary instruments in an emergency. One of the portholes was equipped with a Vzor optical sight built by TsKB-558 (Central Design Bureau No. 558) that allowed the cosmonaut to visually check the spacecraft’s attitude. While small, the cabin was roomy enough for the cosmonaut to float out of his seat.
The instrument module, now mounted at the base of the spacecraft, carried all the equipment not needed for the return to Earth. It was now a double cone shape about 2.4 meters in diameter and about as tall with a mass of 2,300 kilograms. It was connected to the descent module by straps and an umbilical arm designed to burn away in case they failed to separate before reentry. This module carried various consumables for life support, the attitude control system, batteries, telemetry systems and a liquid propellant TDU-1 retrorocket at its base. Producing 16 kilonewtons of thrust for 45 seconds, the TDU-1 was built by OKB-2 under Alexei M. Isayev. Spacecraft attitude was controlled automatically by gas jets using inputs from solar and infrared sensors as well as a “gyrohorizon”. This system had to orient the spacecraft precisely when the TDU-1 fired in order to make a survivable ballistic reentry. As a backup, the cosmonaut could control the spacecraft’s orientation and fire the TDU-1 manually. The descent module had no active attitude control and used aerodynamic forces in conjunction with an offset center of gravity to maintain orientation during reentry.
Soviet cutaway diagram of the Vostok mounted on top of the Blok E stage of its 8K72K launch vehicle. Click on image to enlarge. (RKK Energia)
Since mass restriction did not allow sufficient redundancy in the TDU-1 retrorocket, the spacecraft employed an interesting backup system to return to Earth: Atmospheric drag. The spacecraft would be placed into a 250-kilometer orbit that would naturally decay in ten days or less. The Soviet spacecraft was designed from the start with a ten day endurance so that if the TDU-1 failed, the cosmonaut still had a chance to return to Earth alive. While initial plans called for the first manned mission to last a day, this ten-day capability would allow the Soviets to attempt missions many times longer than those planned for the much smaller Mercury capsule. The entire spacecraft would be housed inside an aerodynamic shroud mounted on top of the 8K72K launch vehicle. This unified Object K design received an official blessing in the form of a government decree on May 22, 1959.
Moving Towards the First Launch
As a debate raged about the relative priority of the manned and unmanned reconnaissance versions of Object K, work on Vostok continued all through 1959. In March the basic hull drawings were completed. By May design details were available and work started on the fabrication of actual systems. By the end of 1959 a pair of Vostok “electrical analogs” were being tested in the shops at OKB-1. Ultimately a plan was adopted that allowed for the development of both Vostok variants to continue but with manned flights given priority for political and propaganda purposes. On December 10, 1959 a decree was issued to proceed.
By March of 1960, 20 cosmonaut candidates had started training. Unlike the Mercury 7, their identities remained a secret in some cases for years (see “Project Mercury: Choosing the Astronauts & Their Machine”). Finally in April 1960 a draft project outline, which Korolev had been following for months anyway, was officially accepted. It called for the development of three Vostok variants. Object 1K, also called Vostok-1, would be a prototype vehicle meant to test the basic spacecraft design and systems. Next was Object 2K reconnaissance variant that sold be later known as Zenit-2. Finally there was the Vostok-3 or Object 3K which would actually carry a cosmonaut into orbit.
Soviet cutaway diagram of Object 1KP used for the first Vostok test flight. Click on image to enlarge. (RKK Energia)
By the spring of 1960 the first Object 1KP was ready for launch (with the “P” standing for “prostoy” – Russian for “simple”). The 1K incorporated most of the elements of the manned 3K design except the 1K had a mast on top of the descent module carrying a small solar array in addition to the batteries which would normally power Object K. Shaped like a pair of half-disks a meter across, this system called “Luch” (Russian for “ray”) carried its own orientation system and would evaluate the use of solar panels for supplying power on future long duration spacecraft. The 1KP prototype contained all the basic systems of the 1K except for life support and a heat shield. This three or four-day test flight would simply evaluate the performance of the basic Vostok design in orbit up to and including the firing of the retrorocket and the separation of the modules prior to reentry. With no heat shield, an actual recovery would not be attempted. The lack of a heat shield also meant that the spacecraft could not accidentally land outside of the Soviet Union in case control was lost. Although work on the new 8K72K launch vehicle proceeded steadily through 1959, the decision was made that the first prototype test flights would use the existing 8K72.
Drawing the the Vostok and its launch vehicle in its launch configuration. Click on image to enlarge. (RKK Energia)
The Flight of Korabl Sputnik
With the first 1KP spacecraft already shipped ahead of them to the Baikonur Cosmodrome in Soviet Kazakhstan on board an Antonov An-12 cargo plane, the engineers and technicians arrived on April 28, 1960 to prepare the first Vostok for launch in early May. Ongoing problems with the complex “Chayka” (“seagull”) spacecraft orientation system resulted in several days of delay and was not installed until May 5. Continuing problems postponed the first integrated testing of all spacecraft systems until May 12. The final mass of 1KP No. 1 came in at 4,540 kilograms of which 1,477 kilograms was instrumentation. The spacecraft was over three times more massive than NASA’s Mercury and it would not be until the first unmanned test flight of the Apollo in 1966 that the US would launch a larger crewed spacecraft prototype (see “The First Flight of the Apollo-Saturn IB”).
A view of Object 1KP No. 1, named Korabl-Sputnik once in orbit, and its Blok E stage at the time of launch on May 15, 1960. (RKK Energia)
With 1KP No. 1 mounted on 8K72 number L1-11, the rocket was rolled out to the pad at Site 1 for the final preparations for launch. At 03:00:05 Moscow Time (00:00:05 GMT) on May 15, the first Vostok prototype smoothly lifted off towards orbit. After 461 seconds of powered flight, the Blok E stage of the rocket shutdown placing the spacecraft in an initial 312 by 369 kilometer orbit with an inclination of 65°. Although the spacecraft was called “Korabl-Sputnik” (“satellite ship”) in the official TASS announcement of the launch, the payload was more widely known as “Sputnik 4” in the West.
Over the following days, the prototype spacecraft was thoroughly tested without any major incidents. Prior to the planned return of Korabl-Sputnik on the morning of May 19, ground controllers became concerned about the Chayka attitude control system. While the system seemed to be functioning, there were concerns that the infrared sensor was not responding correctly. A recommendation to switch to the simpler Sun senor-based “Grif” backup attitude control system for the upcoming retrograde maneuver was made but rejected by Korolev and others in charge.
During its 64th orbit, Korabl-Sputnik used is attitude control jets to reorient itself and, at 02:52 Moscow Time on May 19, the TDU-1 engine was successfully ignited followed by the separation of the modules. As some on the engineering team had feared, the Chayka system had failed to orient the spacecraft properly and instead of sending the spacecraft towards a destructive reentry, Korabl-Sputnik instead went into a higher 307 by 690 kilometer orbit. While Western observers took this “mishap” as a mission failure, in reality Korabl-Sputnik met almost all of its objectives and continued to operate for another four days in its new orbit before its batteries were exhausted. On June 4, as the data from the first mission were still being assessed, the launch of the first manned Vostok was officially set for December 1960 in order to beat NASA’s schedule manned Mercury flight. While the goal was achievable, there was still much work to be done.
The fragment of Korabl-Sputnik which landed in Manitowoc, Wisconsin on September 6, 1962. The ruler to the right is in units of inches.
The orbits of Korabl-Sputnik’s descent and instrument modules finally decayed on September 6, 1962 and October 15, 1965, respectively. In an odd postscript to this flight, some of the debris from the spacecraft’s descent module survived the destructive reentry in 1962 with a 9-kilogram piece coming down in the middle of North 8th St. in the city of Manitowoc, Wisconsin. This event is now commemorated during “Sputnikfest” held at the city’s Rahr-West Museum a dozen or so meters from the impact site.
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Related Reading
“Vostok’s Legacy”, Drew Ex Machina, April 12, 2015 [Post]
“The Origins of NASA’s Mercury Program”, Drew Ex Machina, December 17, 2018 [Post]
General References
Boris Chertok, Rockets and People Volume III: Hot Day of the Cold War, SP-2009-4110, NASA, 2009
James Harford, Korolev: How One Man Masterminded the Soviet Drive to Beat America to the Moon, Wiley, 1997
Nicholas L. Johnson, Handbook of Soviet Manned Space Flight, Univelt, 1980
John Rhea (editor), Roads to Space: An Oral History of the Soviet Space Program, Aviation Week Group, 1995
Yuri P. Semenov (editor), Racketno-Kosmicheskaya Korporatsiya ‘Energia’ Imeni S P Koroleva (in Russian), RKK Energia, 1996
Timothy Varfolomeyev, “Soviet Rocketry That Conquered Space Part 3: Lunar Launchings for Impact and Photography”, Spaceflight, Vol. 38, No. 6, pp. 206-208, June 1996
Timothy Varfolomeyev, “Soviet Rocketry that Conquered Space Part 7: Launch Vehicles for the First Reconnaissance Satellite”, Spaceflight, Vol. 40, No. 9, pp. 360-363, September 1998
Peter A. Gorin, “Zenit – The First Soviet Photo-Reconnaissance Satellite”, Journal of the British Interplanetary Society, Vol. 50, No. 11, pp. 441-448, November 1997
Bart Hendrickx, “Korolev: Facts and Myths”, Spaceflight, Vol. 38, No. 2, pp. 44-48, February 1996
Asif A. Siddiqi, “Before Sputnik: Early Satellite Studies in The Soviet Union 1947-1957 – Part 2”, Spaceflight, Vol. 39, No. 11, pp. 389-392, November 1997
Asif A. Siddiqi, Sputnik and the Soviet Challenge, University Press of Florida, 2000