Category Energiya-Buran


Even as officials were still pondering over the need to respond to the Space Shuttle, specialists were already busy figuring out what the Soviet equivalent should look like. Glushko had not come to NPO Energiya empty-handed. He and his engineers at Energomash had devised plans for a new family of heavy-lift launch vehicles called RLA, which stood for “Rocket Flying Apparatus”. This was the same term that Glushko had used for some experimental liquid-fuel boosters he had developed way back in the early 1930s while working for the Gas Dynamics Laboratory in Lenin­grad. In Glushko’s original vision, the Soviet shuttle was going to be just one payload for the RLA family.

With Glushko’s background in engine development, it was logical that his initial efforts at NPO Energiya focused mainly on launch vehicles. Until then he had only concentrated on designing and building the rocket engines themselves, with other design bureaus (Korolyov, Chelomey, Yangel) being responsible for building the rockets that were powered by those engines. Now, with the merger of Energomash and TsKBEM, Glushko received the infrastructure and workforce to design not only engines, but also the rockets themselves.

The RLA plan revolved around two key concepts. First, it required the development of a new generation of powerful rocket engines using liquid oxygen (LOX) as oxidizer, and kerosene and hydrogen as fuel. Second, it envisaged the use of standardized rocket stages that could be assembled into different configurations tailored to the specific payloads to be placed into orbit.

Orbiter names and mission designators

The name Buran was first publicly applied to the orbiter individually when the TASS news agency announced the launch date for the first mission on 23 October 1988. Actually, the name originally painted on the first flight vehicle had been “Baykal” (after the famous Siberian lake), but this was later erased. Strictly speaking, Buran had now become the name of the vehicle that made the one and only Soviet shuttle flight on 15 November 1988, placing it on an equal footing with NASA’s Shuttle Orbiter names Enterprise, Columbia, Challenger, Discovery, Atlantis, and Endeavour. However, since Buran was the only vehicle ever flown, the name later also began to be used for Soviet orbiters in general, as it will be in this book.

It is not known what official names the other vehicles would have been given had they ever flown. The only other ship that came close to flying was sometimes referred to in the press as “Buran-2’’, but it is unclear if this would have become its official name. A persistent myth is that it was called Ptichka (“Birdie”), which actually was a general nickname for Soviet orbiters that somehow got misinterpreted by Western journalists as being the name of the second orbiter. There is some speculation that it was to be dubbed Burya (“Storm”), continuing a tradition of naming orbiters and some heavy-lift launch vehicles and their upper stages after violent natural phenom­ena. Burya, incidentally, had also been the name of the Lavochkin bureau’s cruise missile that won the competition from Myasishchev’s Buran back in the 1950s. Presumably, the Russians would have given this matter serious thought only if the second orbiter had entered final launch preparations, which it never did. No name was ever painted on this vehicle and therefore it can be said that it was never officially named.

The individual vehicles did have designators comparable with the OV designators of the US Shuttle Orbiters (OV-099, 101, 102, 103, 104, 105). Buran was 1K, the second orbiter was 2K, the third one 3K, etc. These designators also appeared in the mission designations. The first flight of orbiter 1K was 1K1, the (planned) first flight of orbiter 2K was 2K1, etc. In documentation these numbers were also used to refer to the vehicles themselves, so “vehicle 1K1’’ would be “flight vehicle 1 as configured for its first mission’’. Some Western publications claimed the first flight was desig­nated “VKK-1”, but this is not true. VKK (Vozduzhno-Kosmicheskiy Korabl) literally means “aerospace ship’’, a general term for winged spacecraft, although it is most often used for single-stage-to-orbit spaceplanes. Within NPO Molniya the airframes of the flight articles had designators such as 1.01, 1.02 (for the first two orbiters) and 2.01 (for the third orbiter).

Even though the word “Buran” has been used to refer to different things at different times and the name “Energiya” was not introduced until 1987, for the sake of clarity the two names will be used further in this book to refer to the orbiter and the rocket, respectively, irrespective of when the events discussed took place.


Like all earlier Soviet manned spacecraft, Buran used a mixed oxygen/nitrogen atmosphere very similar in composition and pressure to what we breathe on Earth. NASA did not introduce the oxygen/nitrogen mix until the early 1970s on Skylab, having used 100% oxygen atmospheres on Mercury, Gemini, and Apollo. A 100 per­cent oxygen atmosphere allows for the construction of lighter vehicles and obviates the need for spacewalk pre-breathing, but, on the other hand, significantly increases the fire hazard, as vividly demonstrated by the Apollo-1 fire in 1967.

Buran had three subsystems to provide the crew with breathable air both in standard and emergency situations. These were the Pressurization and Depressuriza­tion System (SNiR), the Gas Composition System (SGS), and the Personal Life Support System (ISZhO). The SNiR maintained cabin absolute pressure between 93.3 and 107.3 kilopascals (kPa), supplying oxygen and nitrogen to the cabin from tanks situated in the mid fuselage. As on the Shuttle Orbiter, the oxygen was stored cryogenically in the tanks of the fuel cell system. The SNiR would pump up to 1.5 kg of air into the crew module per day to compensate for routine loss of cabin air and would also repressurize the airlock after spacewalks. The system was automatically activated whenever cabin pressure sank to 98.7 kPa and would then repressurize it to a level of 101.3 kPa. It could also be operated via manually controlled valves. The SNiR was also designed to respond to various emergencies. It could replace the cabin air after a fire or a malfunction of the carbon dioxide removal system and in case of cabin depressurization due to a micrometeorite or space debris impact would blow air into the cabin to give the cosmonauts more time to don pressure suits. If Buran was to have re-entered with a depressurized cabin, the SNiR would have opened a valve to allow outside air to stream into the cabin and minimize pressure differences.

The SGS maintained oxygen partial pressure between 18.7 and 29.3 kPa, making sure that oxygen levels never exceeded 40 percent to limit the fire hazard. The system kept carbon dioxide partial pressure below 1.07 kPa. This was accomplished with regenerators in which CO2 reacted with potassium superoxide to produce oxygen, which was then recirculated to the cabin air. The ratio of absorbed CO2 to regen­erated oxygen was roughly the same as the respiratory quotient of a human being— that is, the ratio of the volume of carbon dioxide released to the volume of oxygen consumed by the body. The regenerators also had filters to remove trace contami­nants from the cabin atmosphere. Similar C02 removal systems had also flown on earlier Soviet piloted spacecraft.

Depending on crew size and mission duration, Buran would have needed to carry 6 to 18 regenerators on a single flight. The crew’s responsibility was to regularly rehook flexible hoses between cabin ventilators and the regenerators as the potassium superoxide ran out. The Shuttle Orbiter has usually relied on non-regenerative lithium hydroxide canisters for C02 removal, as many as 30 of which may be needed on a single flight. NASA did install a regenerative carbon dioxide removal system on the Orbiters Columbia and Endeavour for Extended Duration Orbiter missions, but it did not produce oxygen as a byproduct of the chemical reaction.

The ISZhO was primarily designed to provide life support functions to a full pressure suit that the crew was supposed to wear during critical mission operations such as launch, docking, undocking, and re-entry. Called Strizh (“Swift”—the bird), the suit was derived from the Sokol (“Falcon”) pressure suits worn by Soyuz cosmonauts and adapted to be used in conjunction with ejection seats. The system could operate either in an open-cycle or closed-cycle mode. With the loop open, the suit was ventilated with cabin air, which was then released back into the cabin via the helmet (if that was open) or through pressure regulators (if the helmet was closed). With the loop closed, oxygen was supplied to the suit from the fuel cell liquid-oxygen tanks or (if that didn’t work) from back-up gaseous oxygen tanks. There were also small portable oxygen containers that could sustain a crew member for 20 minutes. After having passed through the suit, the air moved through a contamination control assembly to remove carbon dioxide and other gases and through a unit that cooled the air and removed the moisture. Finally, the gas was enriched with oxygen and recirculated through the suit. The main operating pressure of the suit was 440 hecto – pascals (hPa), but could be manually reduced to 270 hPa. A single ISZhO unit formed a ventilation loop for two suits.

The system automatically switched from open loop to closed loop in the event of cabin depressurization or when smoke or other harmful substances were detected in the crew module. The closed-loop mode could also be manually activated by the crew. If the crew members were in shirtsleeves during cabin depressurization, they were able to individually don the Strizh within five minutes, with the SNiR supplying enough air to the cabin to keep them alive during that time (assuming the leak wasn’t too big). Since as many as 12 hours could elapse between depressurization and an emergency landing, the Strizh also had a waste collection and water supply system. The suits were put to the test in 1990-1991 at a vacuum chamber of the Air Force Scientific Test Institute in Akhtubinsk, when test engineers wore the suits for up to 18 hours, including 12 hours in a mode simulating a depressurized cabin. Unlike the Strizh suits, the pressure suits worn by Space Shuttle astronauts only provide protection during launch and entry, not during in-orbit emergencies.

An additional task of the ISZhO was to support a cosmonaut clad in an Orlan spacesuit during pre and post-spacewalk operations in the airlock, thereby increasing the resources of the suit during the spacewalk itself. More particularly, the system was used to feed oxygen to the suits, to cleanse and cool the air circulating in the suit, and provide water to the cooling garment. The ISZhO was also used to dry the spacesuits in preparation for the next spacewalk.

For unmanned missions the oxygen content in the cabin atmosphere was sup­posed to be lower to reduce the fire hazard. For instance, Buran had a 90 percent nitrogen/10 percent oxygen atmosphere on its one and only mission in 1988.

The SNiR and SGS were developed by the NPO Nauka organization in Moscow, while the ISZhO and associated pressure and spacesuits were products of the Zvezda organization in Tumilino just outside Moscow [17].


Buran’s communication systems performed the following functions:

– two-way voice communications between the orbiter and Mission Control and between the orbiter and other spacecraft;

– intercom between crew members inside the vehicle and between crew mem­bers inside and outside the vehicle;

– relay to the ground of television images;

– relay to the ground of telemetry about the crew’s health, condition of on­board systems, payload-related activities;

– trajectory measurements to determine the vehicle’s exact orbital parameters;

– interaction between ground-based and on-board computers.

There were three independent radio systems, operating in three different wavebands (roughly equivalent to the Space Shuttle’s P-band, S-band, and Ku-band commun­ication systems):

– Meter waveband (VHF): for direct line-of-sight communications with ground stations, tracking ships, and the landing facility, and also for inter­com. This system used omnidirectional antennas.

– Decimeter waveband (UHF): for communications with ground stations and tracking ships either directly or through geostationary relay satellites. Equipped with three transceivers, this system used two omnidirectional an­tennas and five active-phased array antennas.

– Centimeter waveband (SHF): solely for communications through geo­stationary relay satellites using two parabolic narrow-beam antennas. One of these (ONA-I) was mounted on the aft wall of the payload bay, covering the upper hemisphere, and the other (ONA-II) was located in a well on the underside of the aft fuselage, covering the lower hemisphere. ONA-I could be moved off-axis so that its view to the geostationary satellite was not blocked by the vehicle’s vertical stabilizer. Depending on the mission objec­tives and the vehicle’s orientation, the antennas could be used either together or individually. Both antennas could only be deployed in orbit and had to be stowed for a safe re-entry. Therefore, they could be pyrotechnically jet­tisoned if something went wrong during the stowage process. The ONA antennas performed the same role as the Shuttle’s Ku-band antenna, the major difference being that the Shuttle has just one such antenna installed on the starboard side of the payload bay that covers both hemispheres. The ONA antennas were not installed on Buran’s single mission in November 1988.

The data relay satellites intended for use by Buran were the Luch/Altair satellites, approved by the same February 1976 government decree that had given the go-ahead for the Energiya-Buran program. The equivalent of NASA’s Tracking Data and Relay Satellites (TDRS), these were 2.4-ton three-axis stabilized satellites designed to relay communications from and to both Buran and the Mir space station and also to provide mobile fleet communications for the Soviet Navy. They were developed by the Scientific Production Association of Applied Mechanics (NPO PM) near the Siberian city of Krasnoyarsk. Five were launched between October 1985 and October 1995.

Luch/Altair satellite (source: Novosti kosmonavtiki).

Buran’s communication systems were developed by the Moscow-based organ­ization NPO Radiopribor (currently named Russian Scientific Research Institute of Space Equipment Building or RNII KP). Headed throughout the Buran years by Leonid I. Gusev, this organization had a virtual monopoly in developing commun­ication systems for Soviet spacecraft [25].


NPO Energiya, the former “Korolyov design bureau”, was the organization in charge of the Energiya-Buran project as a whole, performing a role comparable with that of a “prime contractor” in the West. NPO Energiya was responsible for making all key technical decisions and coordinating work between the numerous organiza­tions. Situated in the Moscow suburb of Kaliningrad (renamed Korolyov in 1996), it was initially part of the N11-88 rocket research institute founded in 1946, but split off from that organization along with Factory 88 to form the independent OKB-1 (Experimental Design Bureau 1) in 1956. It was renamed Central Design Bureau of Experimental Machine Building (TsKBEM) in 1965, NPO Energiya (NPO standing for “Scientific Production Association”) in 1976, and RKK Energiya (RKK standing for “Rocket and Space Corporation”) in 1994. Factory 88 was renamed Factory of Experimental Building (ZEM) in 1967.

Placed in charge of NPO Energiya in May 1974 was Valentin P. Glushko, who thereby relinquished his duties as chief designer of KB Energomash, the rocket engine design bureau that had merged with TsKBEM to form NPO Energiya. Being a member of the Academy of Sciences (since 1953) and a member of the Central Committee of the Communist Party (since 1976), Glushko had considerable political clout and enjoyed almost unconditional support from Dmitriy Ustinov. Initially, Glushko was both “general designer” and “director” of NPO Energiya, but in June 1977 Vakhtang D. Vachnadze was assigned to the newly created post of “general director” to handle the organization’s day-to-day administrative affairs. Glushko died in January 1989 and was replaced in August 1989 by Yuriy P. Semyonov, who was initially only general designer, but also took over the post of general director from Vachnadze in March 1991.

By late 1977 work on the Energiya-Buran project at NPO Energiya was con­centrated in Department 16. Igor N. Sadovskiy was the chief designer of Energiya – Buran as a whole, with Yakob P. Kolyako, the former head of the heavy-lift launch vehicle section, serving as deputy for the rocket, and Pavel V. Tsybin as deputy for the orbiter. There were changes in the wake of a December 1981 party and government decree calling for organizational improvements in the Energiya-Buran program. Responsibility for the orbiter was transferred to design Department 17 of Yuriy P. Semyonov (Soyuz-Salyut), while Department 16 remained in charge only of the rocket. In January 1982 Sadovskiy, who had been on bad terms with Glushko, was replaced as chief designer of Energiya-Buran by Boris I. Gubanov, a veteran of KB Yuzhnoye in Dnepropetrovsk, who had played a key role in the development of missiles such as the R-14, R-36, and R-36M. From that moment on Gubanov was chief designer of the Energiya-Buran system as a whole and also chief designer of the rocket, while Semyonov was chief designer of the orbiter. Sadovskiy became Gubanov’s first deputy, while Vladimir A. Timchenko served as Semyonov’s deputy for the orbiter.

On the production side, NPO Energiya’s ZEM manufacturing facility was in

Energiya-Buran chief designers Igor Sadovskiy (left) and Boris Gubanov.

charge of building many key systems needed for orbital flight—in particular, the orbital maneuvering engines and primary thrusters of the ODU propulsion system as well as the power supply system. These parts were then shipped either to the Tushino Machine Building Factory or to Baykonur for installation in the vehicle. ZEM also housed a full-scale “electrical analog” of Buran (the so-called “Integrated Stand” or OK-KS).

ZEM also manufactured several parts of Energiya’s strap-on boosters. In the mid-1970s an agreement had been reached that KB Yuzhnoye in Dnepropetrovsk would only build the so-called “modular part’’ of the strap-ons—in other words, the part that was common to the strap-ons and the Zenit first stage. Most of what was unique to the strap-ons would have to be built at ZEM—in particular, the nose and tail sections of the boosters, the parachute containers, drain valves, and actuators. According to original plans, final assembly of the strap-on boosters was to take place at ZEM, but later it was decided to move this work to the Baykonur cosmodrome. The parts manufactured at ZEM were delivered to Baykonur by rail and integrated with the modular part in situ at the cosmodrome. Finally, ZEM also manufactured the pneumatic and hydraulic systems for the Energiya core stage. Directors of ZEM during the Buran years were Viktor M. Klyucharyov (1966-1978) and Aleksey A. Borisenko (1978-1999) [2].

The landing complex (PK OK)

Very early on in the program a decision was made to build a runway at the Baykonur cosmodrome not only to receive Buran at the end of its missions, but also to deliver Buran and elements of the Energiya rocket to the cosmodrome by the VM-T Atlant and eventually Mriya. NPO Molniya was assigned as prime contractor for the construction of the runway by a party/government decree on 21 November 1977.

Baykonur has had an aerodrome (“Krayniy”) since the early days of its existence, but this is situated close to the city of Leninsk, many dozens of kilometers to the south of the launch facilities, and was therefore not suited for this role. Requirements for the location of the new runway were that it had to be outside the “blast zone” of the Energiya pads and be capable of receiving Buran from either side, both during nominal missions and in launch emergencies. The new facility (called PK OK or 11P72) was eventually built some 6.5 km to the northwest of the UKSS complex and 11 km to the northwest of the Raskat complex.

The central part of the landing complex was a 4.5 km long and 84 m wide runway called Yubileynyy (“Jubilee”), capable not only of receiving Buran, but also planes with a take-off mass of up to 650 tons. The surface layer was made of reinforced concrete with a thickness varying between 26 and 32 cm above an 18 to 22 cm sand/ cement ground layer. This concrete, which was about 1.5 to 2 times stronger than the type used on ordinary runways, was produced in six factories located at a consider­able distance from the runway. This created serious transportation problems since the concrete could remain in liquid state for only one and a half hours before being poured onto the runway. The surface had to be extremely flat, with deviations of no more than 3 mm over a 3 m stretch (compared with 10 mm on ordinary runways). To achieve this, the complete 378,000 m surface of the runway had to be ground like parquet floor with special milling machines.

The Buran landing complex: 1, Yubileynyy runway; 2, asphalt stretches; 3, off-loading area; 4, Buran detanking area; 5, main road linking landing complex with other facilities; 6, railway; 7, command and control building (OKPD); 8, airplane parking platform (source: Dennis Hassfeld).

At either end of the runway was a 500 m long and 90 m wide stretch of asphalt to give Buran more leeway during emergency landings. Running parallel to the main runway at a distance of some 50 m was a 4.5 km long and 100 m wide dirt runway apparently intended for emergency landings by planes, with no role in the Buran program.

Adjacent to the runway were several facilities:

– A platform to drain liquid oxygen, gaseous oxygen, and liquid hydrogen from Buran’s fuel cells and the ODU propulsion system.

– A platform to off-load Buran and elements of the Energiya rocket from their carrier aircraft. This has two mate-demate devices called PKU-50 and PUA-100 capable of handling payloads of 50 and 100 tons, respectively.

Buran being installed atop Mriya using the PUA-100 mate-demate device (source: Sergey Grachov).

– A “waiting platform” for vehicles needed to service Buran after landing.

– A parking platform for airplanes.

– An airplane-servicing area.

Also located in the vicinity of the runway was the ground segment of the Vympel navigational aid system (Vympel-N). This included six transponders for the RDS system (only three of which were required for landing), one beacon for the RSBN system, four beacons for the RMS microwave landing system, and a set of radars.

The nerve center of the landing complex was a six-story high command and control building (OKPD) that acted as a control center for the landing phase, work­ing in conjunction with the TsUP Mission Control Center near Moscow. The build­ing had one big control room for Buran and another for ordinary air traffic control tasks [16].


By mid-1989, several months after Buran’s maiden flight on 15 November 1988, plans were finalized for a second mission that would far exceed the first one in complexity. The mission would use the second flight vehicle (2K, sometimes called “Buran-2”) and was therefore dubbed 2K1. The plan was for the orbiter to be launched unmanned and fly to the Mir space station, where it would dock with the axial APAS-89 docking port of the Kristall module. Before that, Kristall would be relo­cated from its lateral port on the Mir multiple docking adapter to the station’s front axial port. After docking, the Mir resident crew would board the orbiter to determine the state of its on-board systems, with one of the possible objectives being to use the vehicle’s remote manipulator arm to move a payload from the payload bay to Kristall’s lateral APAS docking port. One NPO Energiya official said that the pay­load was a small one-ton module housing a Fosvich X-ray telescope similar to the one on Mir’s Kvant module. See [69]. Also installed in the payload bay would have been a pressurized module (37KB) about the size of the Kvant module with instrumentation to record various flight parameters.

Subsequently, the orbiter would undock and continue its flight autonomously. Around the same time, a manned Soyuz equipped with an APAS-89 docking port would be launched to dock with the orbiter. The crew would transfer to the orbiter and perform one day of testing. After the Soyuz undocked, it would fly on to Mir to link up with Kristall, while the unmanned 2K orbiter returned back to Baykonur after a one-week mission [70].

In the late 1980s NPO Energiya was ordered to build three Soyuz spacecraft (serial numbers 101, 102, 103) with APAS-89 docking ports. These vehicles were intended in the first place for possible rescue missions to stranded Buran crews during the test flight program, but it was decided to use the first one in the framework of the

2K1 mission [71]. The flight was partially seen as a dress rehearsal for such a potential rescue mission.

LII demanded that at least one of its Buran pilots be included in the Soyuz crew to give him the necessary experience for the first manned Buran mission [72]. With no or few Soyuz seats available in the mainstream Mir program, this was the ultimate opportunity for a Soyuz familiarization flight, the more so because it involved Buran itself. However, in 1990 a training group was formed for the Soyuz mission consisting of three GKNII pilots and three TsPK military engineers:

Stepanov and Fefelov were assigned in April 1990 and the others in October/ November 1990. It is not entirely clear if training advanced to the point that actual crews were formed, although Kadenyuk has claimed he was in the second back-up crew with Fefelov [73]. The most active training was performed by the three pilots, who faced the unprecedented task of docking Soyuz with Buran. All three spent many hours in TsPK’s Soyuz simulators, practicing dockings both with Buran and Mir. The three engineers reportedly never underwent any dedicated mission training [74].

During a break from training, Aleksey Boroday relaxes for a moment with his son besides a small lake in Star City (B. Vis files).

The 2K1 mission was originally scheduled for 1991, but kept slipping as future prospects for the Buran program grew ever dimmer. Officially, the three pilots and Illarionov remained assigned until March 1992, and Fefelov and Stepanov until October 1992 [75]. Kadenyuk has said the mission was officially canceled in August 1992 [76].

Soyuz craft nr. 101 was eventually launched as Soyuz TM-16 on 24 January 1993, carrying another resident crew (Gennadiy Manakov and Aleksandr Poleshchuk) to the Mir space station. Equipped with an APAS-89 docking port, it was the only Soyuz vehicle ever to dock with the Kristall module. Soyuz “rescue” vehicles nr. 102 and 103, which had been only partly assembled, were modified as ordinary Soyuz TM spacecraft with standard “probe” docking mechanisms and were given new serial numbers [77].


Testing of Buran’s ODU propulsion system was the prime responsibility of the so-called Primorskiy Branch of NPO Energiya in the Leningrad region on the shores of the Gulf of Finland. This was set up in 1958 as a branch of Glushko’s OKB-456, mainly to test engines with exotic propellants such as the RD-301 fluorine/ ammonia engine destined for a Proton upper stage. When OKB-456’s successor KB Energomash merged with TsKBEM in 1974 to form NPO Energiya, the Primorskiy Branch became part of the new conglomerate and remained subordinate to it even after Energomash regained its independence in 1990. Its first assignment as part of NPO Energiya was to test the RD-120 engine for the second stage of Zenit. The old RD-301 test stand was refurbished for a series of horizontal test firings of 11D58M engines for the Proton rocket’s Blok-D upper stage in 1978­1982, which were probably seen as precursors to similar tests with the Orbital Maneuvering Engines (DOM or 17D12) for Buran. Between May 1985 and Septem­ber 1988 six 17D12 engines underwent 114 horizontal test firings lasting a total of 22,311 seconds.

Meanwhile, in 1981 construction had begun of a new vertical test stand called V-1 to test complete ODU engine units called EU-597, containing not just the 17D12 engines, but also thrusters and verniers. The first such ODU unit (nr. 10S) began testing in June 1986 but was destroyed in a fire in February 1987, seriously damaging the test stand. V-1 was refurbished for a series of tests with a new unit (nr. 12S) between September 1987 and April 1988 that underwent the complete ODU firing program planned for the first Buran mission. Those tests uncovered a problem that would delay the Buran flight for several months (see Chapter 7). More tests were conducted with unit nr. 31L between June and December 1988 and unit nr. 11S between January 1991 and March 1993. After cancellation of the Energiya-Buran program the unit was mothballed and eventually removed from the test stand. The 17D15 thrusters and 17D16 verniers apparently also underwent individual tests at Nllkhimmash near Zagorsk. Test firings of the ODU integrated in Buran were conducted at Baykonur’s test-firing platform [14].

The Auxiliary Power Units (VSU) underwent a test program at the IS-104 and IS-105 test stands of Nllkhimmash, which included simulated hydrazine leaks to test the fire suppression system. The VSU hydrazine tank was put to the test in simulated weightless conditions aboard an Ilyushin-76 aircraft and also at various ^-levels at Star City’s TsF-18 centrifuge. The VSU test program culminated in the units being installed on Buran and activated at the Buran test-firing stand at Baykonur.

Preparing the stack

The next step in the launch preparation process was for Buran to be mated with its launch vehicle (Energiya rocket 1L) for an experimental roll-out to pad 37. The 1L rocket had always been well ahead of Buran in its launch preparations. Assembly of the core stage in the Energiya assembly building had begun back in October 1986, shortly after work with the core stage for vehicle 6SL had been completed. In early 1988 (14 January-2 February) the 1L rocket had already spent about three weeks on pad 37 for a variety of tests, including firing tests of the hydrogen igniters and retraction tests of the various platforms connecting the launch towers with the rocket.

The Energiya 1L-Buran stack arrived on the pad in the third week of May (the roll-out date has been given both as 19 May and 23 May). Once again a multi­tude of tests were performed, although none of them involved actual fueling of the rocket or the orbiter. One goal of the pad tests was to see if various sources of electromagnetic radiation at Baykonur did not interfere with the operation of on­board systems. The main problems uncovered during the pad tests were with the interaction between the orbiter and rocket computers and with the ground software needed to analyse telemetry at the cosmodrome and in Mission Control.

Actually, the pad tests in May-June were only part of a broader series of exercises at the cosmodrome intended to simulate pre-launch and post-landing operations, including numerous off-nominal situations. Involved in the exercises were not only the launch and recovery teams, but also the LII pilots, who simulated automatic landings on board Tu-154LL aircraft, with the MiG-25-SOTN performing the role of escort aircraft as it would during Buran’s final descent. The exercises also offered the opportunity to test virtually the entire communication network for the mission, including tracking stations, Mission Control in Kaliningrad, and orbiting communications satellites. Ground crews rehearsed post-landing operations and were trained how to deal with a return-to-launch-site abort during ascent. For this purpose, the OK-MT Buran mock-up was transported to the Yubileynyy runway.

The Energiya-Buran stack returned to the assembly building after about 3-4 weeks of tests (the roll-back date has been given both as 10 June and 19 June). Apparently, the original plan was for the orbiter and rocket to undergo some additional tests and then return to the pad for launch in the summer of 1988. Internal planning documents show that in early 1988 the launch was scheduled for July [37]. However, program managers felt that several problems that had surfaced during testing over the preceding weeks needed to be dealt with and decided to remove Buran from the rocket and return it to its MIK OK processing facility.

The most serious problem had cropped up in April during test firings of an ODU propulsion module at the Primorskiy Branch of NPO Energiya near Leningrad. A valve used in the liquid-oxygen gasification system of the primary thrusters failed

Energiya 1L during pad tests in January 1988 (source: Mashinostroyeniye).

to close when commanded to do so, a problem that could jeopardize the operation of the thrusters in flight. Because of this and other issues with the ODU, it was deemed necessary to remove Buran’s ODU module and partially disassemble it to carry out modification work. This also required changes to the flight software, which had already been adapted numerous times in the preceding months, a penalty the

Energiya-Buran inside the MZK building (source: www. buran. ru).

Russians had to pay for flying Buran unmanned. In the end, Buran went into orbit with the 21st version of the flight software.

After repairs to the ODU and integrated electrical tests with the final version of the flight software, Buran was moved back to bay 4 of the Energiya assembly building on 29 August for reintegration with Energiya 1L. With that work complete, the stack was rolled over to the nearby MZK building on 13 September for a series of hazardous and other operations. These included various loading operations (kerosene for the Buran propulsion system, hydrazine fuel and nitrogen gas for the Auxiliary Power Units, ammonia for the thermal control system, air for the cabin repressurization system), installation of batteries aboard Buran, solid-fuel separation motors on the strap-on boosters, and pyrotechnics for the Buran/core stage separation system.

Finally, the large doors of the MZK were opened in the early hours of 10 October and four diesel locomotives began pulling the impressive 3,500-ton combination of Energiya, Buran, and transporter to launch pad 37. In an old tradition, coins imprinted with the roll-out date were placed on the rails before the assembly passed

by and collected afterwards as souvenirs. It took the assembly some 3.5 hours to inch its way to the launch pad. Then another three hours were required to place the stack into vertical position and another hour to connect the Blok-Ya launch adapter to the launch table. All was now ready for final launch preparations to begin [38].

Building Mir-2

By mid-1991 the 2K1 mission had slipped to 1992 from its original launch date in the first quarter of 1991. Beyond that Buran was now scheduled to take part in the assembly and operation of the Mir-2 complex, where the emphasis would be on the industrial production of ultra-pure medicines and semiconductor materials and also on remote sensing. The plans were presented in detail by Yuriy Semyonov at the congress of the International Astronautical Federation in Montreal in October 1991.

First, the 2K orbiter would go up again in 1993 on an unmanned solo flight (2K2) to test some of the biotechnological installations to be flown under the Mir-2 pro­gram. Then in 1994 the 1K vehicle would fly the first manned mission (1K2) as part of a plan sometimes light-heartedly referred to as “Mir-1.5”, in which Mir would gradually be replaced in orbit by Mir-2. After the launch of the Mir-2 core module by a Proton rocket, Buran would rendezvous with the module, grab it with its two remote manipulator arms, and dock it to a bridge in the cargo bay. Buran would then

1K2 mission as planned in late 1991: 1, Buran picks up Mir-2 core module; 2, Buran docks with Mir; 3, Buran mechanical arm transfers Mir-2 core module to Mir lateral docking port (source: Yuriy Semyonov).

link up with a small docking module on Mir’s multiple docking adapter and again use its manipulator arms to transfer the Mir-2 core module to a lateral docking on Mir previously occupied by the Spektr module. The two modules would remain docked for about two years. After the transfer of the Priroda Earth resources module to the Mir-2 core, Mir and its remaining add-on modules would then have been undocked and discarded, setting the stage for the four-year assembly of the Mir-2 complex (1996-2000).

Before that, in 1995, vehicle 2K would be launched on another autonomous flight (2K3) to test a biotechnological module called 37KBT, based on the original 37KB instrumentation modules. With the emphasis having shifted from fundamental scientific research to biotechnological production, the original plans for the 37KBI scientific add-on modules had been scrapped in late 1989. Buran would now regularly fly two biotechnological modules (37KBT nr. 1 and nr. 2), carrying one up and bringing the other down.

Between 1996 and 2000 there would be two missions annually, one using vehicle 2K to swap out the 37KBT biotechnological modules (2K4, 2K5, 2K6, 2K7, and 2K8) and another using the 1K orbiter for assembly and logistics missions (1K3,1K4, 1K5, 1K6, 1K7). Planned for addition to Mir-2 was a 37KBE “power module’’ equipped with extra solar panels. Further Buran missions would have been required to add a large 85 m truss structure to Mir-2 and outfit it with solar arrays, large radiators, and an array of scientific instruments [30].

The “Mir 1.5’’ plan was dropped in 1992, when it was decided that Mir-2 would

Build-up of Mir-2 using Buran orbiters (source: Yuriy Semyonov).

only be launched after Mir had outlived its usefulness. This would also allow the new station to be placed into a higher inclination orbit (65° vs. 51.6° for Mir) for better remote-sensing coverage. At this point the big Buran-launched 37KB-type modules were abandoned in favor of smaller modules based on the Zenit-launched Progress – M2 cargo ship. The new Mir-2 concept was approved by the Council of Chief Designers in November 1992. Although it left open the option of launching the add-on modules and the station’s truss structure with Buran, Zenit was clearly the preferred option. By the time Mir-2 was merged with Freedom to become the Inter­national Space Station in late 1993, work on Buran had been suspended.