Zarya: the Super-Soyuz that only lived twiceby Maks Skiendzielewski
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| It’s that mid-to-late-80s period where a need arose to match the next-generation station with a next-generation crew ferry. And thus, the Zarya was born. |
The development of the spacecraft—also known under its GRAU designation 14F70 and Energia’s internal project code 7K-SM—was approved by a January 27, 1985, resolution of the Military Industrial Commission. Department 178 of NPO Energia, headed by I.L. Minyuk, was tasked with the work, with Konstantin Feoktistov as the project lead. NPO Energia’s General Designer Valentin Glushko personally supervised the project.
Zarya was to take full advantage of the then-new Zenit, a standalone two-stage version of the mighty Energia’s Blok A strap-on booster. The increase in performance over the Soyuz allowed the designers to draw up a larger and more capable space station ferry that would use more modern technology than the two-decade-old design it would have replaced. At a later stage, the spacecraft was to be developed further into a versatile multi-mission vehicle, capable of operating autonomously or aided by a tug, in orbits as high as geostationary and inclinations up to 97°.
By December 22, 1986, preliminary drawings were created, followed by the release in the first quarter of 1987 of the preliminary design. That received some adjustments on review released in May 1988. The capsule was designed to ferry between two and eight crew with cargo to Mir and back, with a certified on-orbit life of at least 195 days (later increased to 270 days). It could also be configured for uncrewed cargo missions, including the return of payloads from orbit, rescue missions to space stations and Buran orbiters, and specialized Ministry of Defense and Academy of Science missions.
Zarya was designed with the Zenit in mind as the launch vehicle, and therefore inherited its 4.1-meter diameter, although the crew module (capsule) itself had a diameter of 3.7 meters. At a length of five meters and launch mass of around 15 tonnes, the capsule would also comfortably fit in Buran’s payload bay.
In the 15-tonne configuration, the Zenit would deliver Zarya to a 190-kilometer reference orbit at an inclination of 51.6°. With two crew, the cargo capacity was 2.5 tonnes with 1.5 to 2 tonnes return, while with no crew the capacity was three tonnes with 2–2.5 tonnes return. With the maximum crew of eight, the capsule would not take any meaningful cargo.
The crew module’s aerodynamic shape was derived from the Soyuz descent module, with a lift/drag coefficient of 0.26 at velocities over Mach 6. The equipment on board was a mix of Soyuz-TM hardware and newly developed units, with the control systems taking full advantage of 1980s computer technology.
Unlike the three-compartment Soyuz, which consists of separate orbital and descent pressurized modules, Zarya only had one large pressurized compartment, which separated from a stubby service compartment before reentry. Like the Soyuz-TM, Zarya could be equipped with either the traditional SSVP “probe-and-drogue” docking assembly, or the APAS-89 system developed for the Buran program—presumably with a small payload penalty, as the APAS system was 120 kilograms heavier—which was protected during launch by a jettisonable cover.
| Zarya was designed with the Zenit in mind as the launch vehicle, and therefore inherited its 4.1-meter diameter. |
The crew module could be reused up to 30 to 50 times thanks in part to the use of Buran-derived reusable thermal protection on the outside of the capsule. During descent, a small drogue chute would deploy to stabilize the vehicle. Instead of a main parachute, the spacecraft was equipped with a ring of liquid-fuel rocket engines that would land the vehicle propulsively. A single-use honeycomb heat shield panel at the bottom of the capsule protected the area with highest thermal load during reentry and doubled as a “crumple zone” upon touchdown to reduce the stresses on the vehicle structure. As this landing method would clearly need some practice to perfect, on the initial flights all crew would be in ejection seats, although that would limit the crew size to four.
In the first two images below, you can see what could be the early ejection seat variant on the left—note the circular ejection hatches in the tile grid—and the fully operational variant with no ejection seat accommodations in the center. On the right is the attachment diagram of the Buran-derived silica tiles.
 Thermal protection system tile layout of the Zarya spacecraft. Left and center legend: I. heatshield-clad honeycomb crumple panel, II. tile mounting on the windward side, III. tile mounting on the leeward side. Images: Novosti Kosmonavtiki, 2014 №8, Tvoy Sektor Kosmosa on YouTube (lecture). |
Twenty-four main engines of the Unified Propulsion System (initially designed for the launch abort system before a Soyuz-style escape tower was chosen), pushing 1.5 tonnes-force of thrust each on a mix of hydrogen peroxide and kerosene, together with sixteen 62 kilograms-force monopropellant orientation thrusters, would be used to land the spacecraft in the Kazakh steppe with an accuracy of just 2.5 kilometers. The landing engines and fuel were located inside the descent module, so a non-toxic propellant mix was chosen for crew safety. Nevertheless, as one can imagine, the acoustic load level on the crew during landing was described as “high”. The acceleration limit was also set rather high at 10G when compared to the modern Soyuz’s 6G, although the contemporary TM series still subjected its passengers to a hefty 12G.
Orbital maneuvering duties were taken care of by the expendable service compartment, analogous to the one on Soyuz. It used two 300 kilograms-force N2O4-UDMH maneuvering engines and a number of orientation thrusters to raise Zarya to the operational orbit (200–550 kilometers) after separation from the Zenit second stage. Radiators were mounted flush with the surface of the compartment around its perimeter.
Interestingly, the standard Zenit did not have quite the performance necessary to lift the heavy capsule, so the second stage tanks were to be filled with syntin instead of kerosene to increase the impulse, and the launch abort system tower would be activated before Zarya separated from the second stage and only jettisoned after it gave the stack the extra push (or rather pull).
 Left: Zarya on top of the Zenit in the Manned Spacecraft Servicing Unit. Right: Various reusable crewed spaceflight projects, including Zarya on Zenit in the leftmost column and possibly an air-launched variant in the rightmost column. Images: HausD via the raumfahrer.net forum, Tvoy Sektor Kosmosa on YouTube (lecture). |
Five major launch configurations were described; Zarya could be easily reconfigured between them without affecting the general layout and systems:
In January 1989, work stopped due to insufficient funding, by which time “main design documentation was completed” at NPO Energia, according to the company history book. Later that year, on October 5, 1989, the Scientific and Technical Council of the Ministry of General Machine Building and the USSR Academy of Sciences, meeting on the topic of Mir-2, “recognized the need to stop work” on Zarya.
While the project never reached the production of flight hardware, some things were built and can still be seen today, namely the “Manned Spacecraft Servicing Unit” for the Zenit at Baikonur’s Site 45, built to service the Zarya-Zenit stack. According to one source, designs for the Zarya were among the items sold to China in the early 1990s when Sino-Russian relations warmed and Chinese officials visited a number of space enterprises in the former USSR.
 The “Manned Spacecraft Servicing Unit” at the Zenit launch site in Baikonur and a drawing of the facility with Zarya and Zenit. Left: I. Marinin. Right: Vovan via the NK Forum. |
Being the prospective replacement of the Soyuz, Zarya played an important role in the Mir-2 plans of the late 1980s. The long on-orbit life resource and larger crew capacity meant that the capsule was a very convenient crew ferry and lifeboat for the large next-generation orbital complex. While relatively few illustrations of either Mir-2 or Zarya have been made public, the even scarcer ones with them both show a version of the future, where instead of Shuttle-Mir-Soyuz we have Buran-Mir-2-Zarya.
Preliminary estimates showed a requirement for two flights of Zarya to supply Mir-2 every year, along with three Progress M2’s and one to two Buran orbiters. In the 1987 draft design of the 180GK version of Mir-2, a modified Soyuz-TM launched on Zenit or a standard Soyuz-TM launched on Soyuz-U2 were described as possible alternatives for Zarya.
 Zarya as part of two variants of the Mir-2 complex. via buran.ru |
However, Mir-2 was not the only station we know of where Zarya could have docked. Before military tensions eased significantly in the 1990s, NPO Energia had been working on a number of space-borne weapons, among them a modular space station for attacking high value ground targets. A DOS-7K-series module would be its core, just like on Mir, but instead of FGB-based science modules, the station would use “autonomous modules” based on the Buran airframe. Wingless orbiters with docking ports in the nose would separate from the station, maneuver to their strike positions and deploy ballistic weapons or BOR-based dive bombers. The Zarya spacecraft would be used to crew the station. The project never got off the drawing board, but Energia’s 1996 company history features an illustration showing how wild this station would have looked.
 “Space station for hitting ground targets 1. Transport ship 7K-SM [Zarya] 2. Command module 3. Base station unit 4. Target station module 5. Combat module”. Semyonov (ed.), 1996. |
Zarya died in January 1989 amid increasing tensions between Feoktistov and Glushko when funding for the project dried up. But the big Soyuz would be reincarnated six years later, if only for a brief moment.
The collapse of the Soviet Union coincided with dramatic delays in and eventual cancellation of the intial GK-180-variant of Mir-2 in mid-1991. The only way for the project to continue was to reconfigure the massive station into a smaller, Mir-1-sized affair or even only use the existing DOS-8 module to replace Mir’s core in orbit and extend the station’s lifespan. Meanwhile, NASA’s Space Station Freedom and its budget had also been shrinking by the minute, with the station losing one of its iconic four solar array pairs in 1991. Throughout the project, there was a clear need for the development or procurement of a rescue vessel for the station: the Space Shuttle could only dock for two weeks and any crew that stayed on a long-duration mission would be stranded if anything went seriously wrong.
| It would launch on shuttle—and hence sport some trunnions for attachment in the payload bay—and stay docked to the ISS for up to five years. |
By 1992, multiple rescue vessel concepts had been investigated under the Assured Crew Return Vehicle (ACRV) project name; the project was just entering the “system definition” phase. The concepts were mostly homegrown designs, ranging from scaled up Apollo command modules to lifting bodies, but some more exotic vehicles like the British “Multi-Role Recovery Capsule” also appeared in submissions to NASA tenders. At the time, the space station was due to start assembly in 1995 but only reach Permanently Manned Capability in 1999 when the ACRV arrived at the station.
In October 1991, the head of NPO Energia, Yuri Semyonov, offered his company’s vehicles as the lifeboat for Freedom until the “proper” ACRV came online and repeated the offer on February 21, 1992, while appearing at a US Senate subcommittee hearing. At least three options were presented: the Soyuz-TM, a clean sheet design resembling the Apollo CM, and a modified version of the cancelled Zarya spacecraft. The last option would be able to seat five to six astronauts and fly on Zenit—like in its ’80s guise—or in the shuttle’s payload bay.
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In March 1992, officials from both countries discussed cooperation in crewed spaceflight and a NASA delegation visited Moscow to “hold exploratory talks on the concept of using Soyuz as an ACRV” and the Soyuz-TM option was developed further. The 1993 agreement to form the International Space Station from the Freedom program and what remained of Mir-2 led to the ACRV program being put on hold until 1997.
In 1995, anticipating a tender from NASA, NPO Energia (which had by that time become RKK Energiya) resumed development of an ACRV, focusing on the Zarya-derived concept and bringing in as partners Rockwell International and, by the end of the year, Khrunichev.
 Russian ISS lifeboat based on the Zarya spacecraft. Semyonov (ed.), 1996 |
The new lifeboat had a launch mass of 12.5 tonnes, sat eight crew and was made up of three sections: the eight-tonne descent module, a short “transition compartment”, and the service module which housed instruments, batteries, fuel tanks, control thrusters, and engines. A larger jettisonable docking assembly with an APAS port joined the ACRV to the station and could be used as an airlock in free flight if needed. The total length of the vehicle was 7.2 meters with the same 3.7-meter capsule diameter. It would launch on shuttle—and hence sport some trunnions for attachment in the payload bay—and stay docked to the ISS for up to five years. The instrumentation was based on the Soyuz-TM.
Work on the vehicle stopped after NASA switched to modified Soyuz-TM as a lifeboat for the first years of the ISS in June 1996. The ACRV program refocused on what would become the X-38, which was itself cancelled in 2001. The Soyuz ended up serving as the station’s lifeboat until 2021, when it started sharing that duty with Crew Dragon.
There is one more chapter to the Zarya story. A later Soyuz replacement, the PTK NP, aka Federatsiya, aka Oryol, also has Zarya heritage. After the Zarya-like large Soyuz descent module became the preferred configuration for the Euro-Russian Advanced Crew Transportation System (ACTS), the design was inherited by PTK NP. The story of ACTS/Oryol is one for another day, but I will sign off with some truly cursed Zarya-derived concepts from Oryol development documentation.
 Federatsiya/Oryol concept with an enlarged Soyuz descent module and an orbital module tumor. RKK Energiya via NK Forum. |
 Federatsiya/Oryol and Kliper variants. RKK Energiya via NK Forum. |
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