The Buran orbital vehicle programme was developed in response to the U.S. Space Shuttle programme, which in the 1980s raised considerable concerns among the Soviet military and especially Defense Minister Dmitry Ustinov. An authoritative chronicler of the Soviet and later Russian space programmes, the academic Boris Chertok, recounts how the programme came into being.^[4] According to Chertok, after the U.S. developed its Space Shuttle programme, the Soviet military became suspicious that it could be used for military purposes, due to its enormous payload, several times that of previous U.S. launch vehicles. The Soviet government asked the TsNIIMash (ЦНИИМАШ, 'Central Institute of Machine-building', a major player in defence analysis) for an expert opinion. Lieutenant General Yuri Mozzhorin recalled that by "approximately 1965", when the Soviet Union had the 'long arm' (ICBMs), the Soviets did not expect war "and thought it would not happen."^[5] As institute director, Mozzhorin, recalled that for a long time the institute could not envisage a civilian payload large enough to require a vehicle of that capacity.^{[citation needed]}

Officially, the Buran orbital vehicle was designed for the delivery to orbit and return to Earth of spacecraft, cosmonauts, and supplies. Both Chertok and Gleb Lozino-Lozinskiy (General Designer and General Director of NPO Molniya) suggest that from the beginning, the programme was military in nature; however, the exact military capabilities, or intended capabilities, of the Buran programme remain classified. Commenting on the discontinuation of the programme in his interview to New Scientist, Russian cosmonaut Oleg Kotov confirms their accounts:

We had no civilian tasks for Buran and the military ones were no longer needed. It was originally designed as a military system for weapon delivery, maybe even nuclear weapons. The American shuttle also has military uses.^[6]

Like its American counterpart, the Buran orbital vehicle, when in transit from its landing sites back to the launch complex, was transported on the back of a large jet aeroplane – the Antonov An-225 Mriya transport aircraft, which was designed in part for this task and was the largest aircraft in the world to fly multiple times.^[7] Before the Mriya was ready (after the Buran had flown), the Myasishchev VM-T Atlant, a variant on the Soviet Myasishchev M-4 Molot (Hammer) bomber (NATO code: Bison), fulfilled the same role.

BackgroundEdit

The Soviet reusable spacecraft programme has its roots in the late 1950s, at the very beginning of the space age. The idea of Soviet reusable space flight is very old, though it was neither continuous nor consistently organized. Before Buran, no project of the programme reached operational status.

The idea saw its first iteration in the Burya high-altitude jet aircraft, which reached the prototype stage. Several test flights were made before it was cancelled by order of the Central Committee. The Burya had the goal of delivering a nuclear payload, presumably to the United States, and then returning to base. The cancellation was based on a final decision to develop ICBMs. The next iteration of the idea was Zvezda from the early 1960s, which also reached a prototype stage. Decades later, another project with the same name was used as a service module for the International Space Station. After Zvezda, there was a hiatus in reusable projects until Buran.

Programme developmentEdit

The development of the Buran began in the early 1970s as a response to the U.S. Space Shuttle programme. Soviet officials were concerned about a perceived military threat posed by the U.S. Space Shuttle. In their opinion, the Shuttle's 30-ton payload-to-orbit capacity and, more significantly, its 15-ton payload return capacity, were a clear indication that one of its main objectives would be to place massive experimental laser weapons into orbit that could destroy enemy missiles from a distance of several thousands of kilometres. Their reasoning was that such weapons could only be effectively tested in actual space conditions and that to cut their development time and save costs it would be necessary to regularly bring them back to Earth for modifications and fine-tuning.^[8] Soviet officials were also concerned that the U.S. Space Shuttle could make a sudden dive into the atmosphere to drop nuclear bombs on Moscow.^[9][10]

In 1974, Valentin Glushko's design bureau, OKB-1 (later NPO Energiya), proposed a new family of heavy-lift rockets called RLA (Russian: РЛА, «Ракетные Летательные Аппараты», romanized: Raketnyye Letatel'niye Apparaty, lit. 'Rocket Flying Apparatus'). The RLA concept included the use of kerosene and liquid hydrogen as fuel, and liquid oxygen as oxidizer (both new technologies in the Soviet space programme), with the shuttle orbiter being one possible payload.^[11] By 1975, NPO Energiya had come up with two competing designs for the orbiter vehicle: the MTKVP (Russian: МТКВП, «Многоразовый Транспортный Корабль Вертикальной Посадки», romanized: Mnogorazoviy Transportniy Korabl' Vertikal'noy Posadki, lit. 'Reusable Vertical Landing Transport Ship'), a 34 meter-long lifting body spaceplane launched on top of a stack of kerosene-fueled strap on boosters;^[12] and the OS-120 (Russian: ОС-120, «Орбитальный Самолет», romanized: Orbital'niy Samolet, lit. 'Orbital Spaceplane–120 tons'), a close copy of the US Space Shuttle composed of a delta-winged spaceplane equipped with three liquid hydrogen engines, strapped to a detachable external tank and four liquid fuel boosters (NPO Energiya even considered the use of solid propellant rocket boosters, further imitating the US Shuttle's configuration).^[13] A compromise between these two proposals was achieved by NPO Energiya in January 1976 with the OK-92 (Russian: ОК-92, «Орбитальный Корабль», romanized: Orbital'niy Korabl', lit. 'Orbital Ship–92 tons'), a delta-winged orbiter equipped with two Soloviev D-30 turbofan jet engines for autonomous atmospheric flight, launched to space from a rocket stack made of a core stage with three cryogenic engines, and four kerosene-fueled boosters, each with four engines.^[14] By 1978, the OK-92 design was further refined, with its final configuration completed in June 1979.^[15]

Soviet engineers were initially reluctant to design a spacecraft that looked superficially identical to the Shuttle. Although it has been commented that wind tunnel testing showed that NASA's design was already ideal,^[16] the shape requirements were mandated by its potential military capabilities to transport large payloads to low Earth orbit, themselves a counterpart to the Pentagon's initially projected missions for the Shuttle.^[17] Even though the Molniya Scientific Production Association proposed its Spiral programme design^[18] (halted 13 years earlier), it was rejected as being altogether dissimilar from the American shuttle design. While NPO Molniya conducted development under the lead of Gleb Lozino-Lozinskiy, the Soviet Union's Military-Industrial Commission, or VPK, was tasked with collecting all data it could on the U.S. Space Shuttle. Under the auspices of the KGB, the VPK was able to amass documentation on the American shuttle's airframe designs, design analysis software, materials, flight computer systems and propulsion systems. The KGB targeted many university research project documents and databases, including Caltech, MIT, Princeton, Stanford and others. The thoroughness of the acquisition of data was made much easier as the U.S. shuttle development was unclassified.^[19]

The construction of the shuttles began in 1980, and by 1984 the first full-scale Buran was rolled out. The first suborbital test flight of a scale-model (BOR-5) took place as early as July 1983. As the project progressed, five additional scale-model flights were performed. A test vehicle was constructed with four jet engines mounted at the rear; this vehicle is usually referred to as OK-GLI, or as the "Buran aerodynamic analogue". The jets were used to take off from a normal landing strip, and once it reached a designated point, the engines were cut and OK-GLI glided back to land. This provided invaluable information about the handling characteristics of the Buran design, and significantly differed from the carrier plane/air drop method used by the United States and the Enterprise test craft. Twenty-four test flights of OK-GLI were performed by the Gromov Flight Research Institute test pilots and researchers after which the shuttle was "worn out". The developers considered using a couple of Mil Mi-26 helicopters to "bundle" lift the Buran, but test flights with a mock-up showed how risky and impractical that was.^[20] The VM-T ferried components^[21] and the Antonov An-225 Mriya (the heaviest airplane ever) was designed and used to ferry the shuttle.^[22][23]

The flight and ground-testing software also required research. In 1983 the Buran developers estimated that the software development would require several thousand programmers if done with their existing methodology (in assembly language), and they appealed to Keldysh Institute of Applied Mathematics for assistance. It was decided to develop a new high-level "problem-oriented" programming language. Researchers at Keldysh developed two languages: PROL2 (used for real-time programming of onboard systems) and DIPOL (used for the ground-based test systems), as well as the development and debugging environment SAPO PROLOGUE.^[24] There was also an operating system known as Prolog Manager.^[25] Work on these languages continued beyond the end of the Buran programme, with PROL2 being extended into SIPROL,^[26] and eventually all three languages developed into DRAKON which is still in use in the Russian space industry. A declassified May 1990 CIA report citing open-source intelligence material states that the software for the Buran spacecraft was written in "the French-developed programming language known as Prolog",^[27] possibly due to confusion with the name PROLOGUE.

Flight crew preparationEdit

Until the end of the Soviet Union in 1991, seven cosmonauts were allocated to the Buran programme and trained on the OK-GLI ("Buran aerodynamic analogue") test vehicle. All had experience as test pilots. They were: Ivan Ivanovich Bachurin, Alexei Sergeyevich Borodai, Anatoli Semyonovich Levchenko, Aleksandr Vladimirovich Shchukin, Rimantas Antanas Stankevičius, Igor Petrovich Volk, and Viktor Vasiliyevich Zabolotsky.

A rule, set in place for cosmonauts because of the failed Soyuz 25 of 1977, insisted that all Soviet space missions contain at least one crew member who has been to space before. In 1982, it was decided that all Buran commanders and their back-ups would occupy the third seat on a Soyuz mission, prior to their Buran spaceflight. Several people had been selected to potentially be in the first Buran crew. By 1985, it was decided that at least one of the two crew members would be a test pilot trained at the Gromov Flight Research Institute (known as "LII"), and potential crew lists were drawn up. Only two potential Buran crew members reached space: Igor Volk, who flew in Soyuz T-12 to the space station Salyut 7, and Anatoli Levchenko who visited Mir, launching with Soyuz TM-4 and landing with Soyuz TM-3. Both of these spaceflights lasted about a week.^[8]

Levchenko died of a brain tumour the year after his orbital flight, Bachurin left the cosmonaut corps because of medical reasons, Shchukin was assigned to the back-up crew of Soyuz TM-4 and later died in a plane crash, Stankevičius was also killed in a plane crash, while Borodai and Zabolotsky remained unassigned to a Soyuz flight until the Buran programme ended.

Spaceflight of I. P. VolkEdit

Igor Volk was planned to be the commander of the first crewed Buran flight. There were two purposes of the Soyuz T-12 mission, one of which was to give Volk spaceflight experience. The other purpose, seen as the more important factor, was to beat the United States and have the first spacewalk by a woman.^[8] At the time of the Soyuz T-12 mission the Buran programme was still a state secret. The appearance of Volk as a crew member caused some, including the British Interplanetary Society magazine Spaceflight, to ask why a test pilot was occupying a Soyuz seat usually reserved for researchers or foreign cosmonauts.^[28]

Spaceflight of A. S. LevchenkoEdit

Anatoli Levchenko was planned to be the back-up commander of the first crewed Buran flight, and in March 1987 he began extensive training for his Soyuz spaceflight.^[8] In December 1987, he occupied the third seat aboard Soyuz TM-4 to Mir, and returned to Earth about a week later on Soyuz TM-3. His mission is sometimes called Mir LII-1, after the Gromov Flight Research Institute shorthand.^[29] When Levchenko died the following year, it left the back-up crew of the first Buran mission again without spaceflight experience. A Soyuz spaceflight for another potential back-up commander was sought by the Gromov Flight Research Institute, but never occurred.^[8]

Ground facilitiesEdit

Maintenance, launches and landings of the Buran-class orbiters were to take place at the Baikonur Cosmodrome in the Kazakh SSR. Several facilities at Baikonur were adapted or newly built for these purposes:

• Site 110 – Used for the launch of the Buran-class orbiters. Like the assembly and processing hall at Site 112, the launch complex was originally constructed for the Soviet lunar landing programme and later converted for the Energia-Buran programme.
• Site 112 – Used for orbiter maintenance and to mate the orbiters to their Energia launchers (thus fulfilling a role similar to the VAB at KSC). The main hangar at the site, called MIK RN or MIK 112, was originally built for the assembly of the N1 moon rocket. After cancellation of the N-1 programme in 1974, the facilities at Site 112 were converted for the Energia-Buran programme. It was here that Orbiter K1 was stored after the end of the Buran programme and was destroyed when the hangar roof collapsed in 2002.^[30][31]
• Site 251 – Used as Buran orbiter landing facility, also known as Yubileyniy Airfield (and fulfilling a role similar to the SLF at KSC). It features one runway, called 06/24, which is 4,500 metres (4,900 yd) long and 84 metres (92 yd) wide, paved with "Grade 600" high quality reinforced concrete. At the edge of the runway was a special mating-demating device, designed to lift an orbiter off its Antonov An-225 Mriya carrier aircraft and load it on a transporter, which would carry the orbiter to the processing building at Site 254. A purpose-built orbiter landing control facility, housed in a large multi-storey office building, was located near the runway. Yubileyniy Airfield was also used to receive heavy transport planes carrying elements of the Energia-Buran system. After the end of the Buran programme, Site 251 was abandoned but later reopened as a commercial cargo airport. Besides serving Baikonur, Kazakh authorities also use it for passenger and charter flights from Russia.^[32][33]
• Site 254 – Built to service the Buran-class orbiters between flights (thus fulfilling a role similar to the OPF at KSC). Constructed in the 1980s as a special four-bay building, it also featured a large processing area flanked by several floors of test rooms. After cancellation of the Buran programme it was adapted for pre-launch operations of the Soyuz and Progress spacecraft.^[34]

MissionsEdit

Following a series of atmospheric test flights using the jet-powered OK-GLI prototype, the first operational spacecraft (Orbiter K1) flew one test mission on 15 November 1988 at 03:00:02 UTC.^[35] The spacecraft was launched uncrewed from and landed at Baikonur Cosmodrome in the Kazakh S.S.R. and flew two orbits, travelling 83,707 kilometres (52,013 mi) in 3 hours and 25 minutes (0.14 flight days).^[36] Buran never flew again; the programme was cancelled shortly after the dissolution of the Soviet Union.^[37] In 2002, the collapse of the hangar in which it was stored destroyed the Buran K1 orbiter.^[38][39]

Atmospheric test flightsEdit

An aerodynamic testbed, OK-GLI, was constructed in 1984 to test the in-flight properties of the Buran design. Unlike the American prototype Space Shuttle Enterprise, OK-GLI had four AL-31 turbofan engines fitted, meaning it was able to fly under its own power.

Orbital flight of Buran 1.01 in 1988Edit

The only orbital launch of the Buran 1.01 was at 03:00 UTC on 15 November 1988 from pad 110/37 in Baikonur. The uncrewed craft was lifted into orbit by the specially designed Energia booster rocket. The life support system was not installed and no software was installed on the CRT displays.^[45] The shuttle orbited the Earth twice in 206 minutes of flight. On its return, it performed an automated landing on the shuttle runway at Baikonur Cosmodrome.^[46]

Planned flightsEdit

The planned flights for the shuttles in 1989, before the downsizing of the project and eventual cancellation, were:^[47]

• 1991 — Ptichka 1.02 uncrewed first flight, duration 1–2 days.
• 1992 — Ptichka 1.02 uncrewed second flight, duration 7–8 days. Orbital manoeuvres and space station approach test.
• 1993 — Buran 1.01 uncrewed second flight, duration 15–20 days.
• 1994 — Orbiter 2.01 first crewed space test flight, duration of 24 hours. Craft equipped with life-support system and with two ejection seats. Crew would consist of two cosmonauts with Igor Volk as commander, and Aleksandr Ivanchenko as flight engineer.
• 1994-1995 - Second, third, fourth and fifth crewed orbital test flights.

The planned uncrewed second flight of Ptichka was changed in 1991 to the following:

• December 1991 — Ptichka 1.02 uncrewed second flight, with a duration of 7–8 days. Orbital manoeuvrers and space station approach test:
  • automatic docking with Mir's Kristall module
  • crew transfer from Mir to the shuttle, with testing of some of its systems in the course of twenty-four hours, including the remote manipulator
  • undocking and autonomous flight in orbit
  • docking of the crewed Soyuz TM-101 with Ptichka
  • crew transfer from the Soyuz to the shuttle and onboard work in the course of twenty-four hours
  • automatic undocking and landing

Cancellation of the programme 1993Edit

After the first flight of a Buran shuttle, the project was suspended due to lack of funds and the political situation in the Soviet Union. The two subsequent orbiters, which were due in 1990 (Orbiter 1.02) and 1992 (Orbiter 2.01) were never completed. The project was officially terminated on 30 June 1993, by President Boris Yeltsin. At the time of its cancellation, 20 billion rubles had been spent on the Buran programme.^[48]

The programme was designed to boost national pride, carry out research, and meet technological objectives similar to those of the U.S. Space Shuttle programme, including resupply of the Mir space station, which was launched in 1986 and remained in service until 2001. When Mir was finally visited by a spaceplane, the visitor was a Space Shuttle orbiter, not a Buran-class orbiter.

The Buran SO, a docking module that was to be used for rendezvous with the Mir space station, was refitted for use with the U.S. Space Shuttles during the Shuttle–Mir missions.^[49]

The cost of a Buran launch carrying a 20 ton payload was estimated at 270 million roubles, vs 5.5 million roubles on the Proton rocket.^[50]

Baikonur hangar collapseEdit

On 12 May 2002, a hangar roof at the Baikonur Cosmodrome in Kazakhstan collapsed because of a structural failure due to poor maintenance. The collapse killed eight workers and destroyed one of the Buran-class orbiters (Buran 1.01), which flew the test flight in 1988, as well as a mock-up of an Energia booster rocket. It was not clear to outsiders at the time which Buran-class orbiter was destroyed, and the BBC reported that it was just "a model" of the orbiter.^[39] It occurred at the MIK RN/MIK 112 building at Site 112 of the Baikonur Cosmodrome, 14 years after the only Buran flight. Work on the roof had begun for a maintenance project, whose equipment is thought to have contributed to the collapse. Also, before the day of collapse, there had been several days of heavy rain.^[8]

Five orbiters were planned to be built (designated 1K-5K, K stands for Корабль, 'craft, flying article'), and hull numbering starts with 1 or 2 (e.g. 1.01), two originally ordered in 1970s and three ("second series") additionally ordered in 1983.^{[citation needed]} For research and testing purposes, several test articles produced, designated 1M-8M (M stands for Макет, 'mock-up'), hull numbering starts with 0 (e.g. 0.02). The programme prefix OK stands for Орбитальный Корабль, 'Orbital Vehicle' and carries the GRAU index number 11F35.

By 1991 two operational vehicles were delivered to Baikonur, three others were under construction at Tushino.

Most of the geo-locations below show the orbiter bodies on the ground; in some cases Google Earth's History facility is required to see the orbiter within the dates specified.^[51][52]

Related test vehicles and modelsEdit

Over time, several scientists looked into trying to revive the Buran programme, especially after the Space Shuttle Columbia disaster.^[66]

The 2003 grounding of the U.S. Space Shuttles caused many to wonder whether the Energia launcher or Buran shuttle could be brought back into service.^[67] By then, however, all of the equipment for both (including the vehicles themselves) had fallen into disrepair or been repurposed after falling into disuse with the collapse of the Soviet Union.

In 2010 the director of Moscow's Central Machine Building Institute said the Buran programme would be reviewed in the hope of restarting a similar crewed spacecraft design, with rocket test launches as soon as 2015.^[68] Russia also continues work on the PPTS but has abandoned the Kliper programme, due to differences in vision with its European partners.^[69][70]

Due to the 2011 retirement of the American Space Shuttle and the need for STS-type craft in the meantime to complete the International Space Station, some American and Russian scientists had been mulling over plans to possibly revive the already-existing Buran shuttles in the Buran programme rather than spend money on an entirely new craft and wait for it to be fully developed^[66][67] but the plans did not come to fruition.

On the 25th anniversary of the Buran flight in November 2013, Oleg Ostapenko, the new head of Roscosmos, the Russian Federal Space Agency, proposed that a new heavy-lift launch vehicle be built for the Russian space programme. The rocket would be intended to place a payload of 100 tonnes (220,000 lb) in a baseline low Earth orbit and is projected to be based on the Angara launch vehicle technology.^[71]

Buran orbiterEdit

The Buran orbiter is built around a "glider", which is its main structural component, since all other components such as wings and the crew cabin are attached to it. The components necessary for flight make up approx. 20% of the weight of the orbiter, while another 11% of weight is added by payload systems and removable parts. The wings of the Buran orbiter contain elevators whose position can be changed from +35° to -20°.^[72]

ExteriorEdit

Similarly to US space shuttle orbiters, Buran orbiters have their exterior covered in 38,600 heat shielding tiles designed to withstand 100 reentries,^[73][74] which themselves were very similar to the ones in the space shuttle,^[75] however, the carbon-carbon Buran heat tiles have an antioxidant molybdenum disilicide coating. The black coating in the carbon-carbon heat tiles helps dissipate heat, and, similarly to the heat tiles used in the space shuttle, Buran heat tiles are glued to the orbiter, and the bottom of the heat tiles are left uncoated to equalize the pressure in the tile with that of its surroundings, preventing additional mechanical loads. The gaps between tiles are deliberate to allow for thermal expansion. The gaps were filled with quartz fiber, rope, alkaline elements, inserts and brush seals, and the carbon-carbon heat tiles were also waterproofed.^[73][76]

The Buran and space shuttle orbiters are exposed to similar temperatures, and both have similar levels of insulation. Buran has a different carbon-carbon heat tile layout in its underside, in which all gaps between heat tiles are parallel or perpendicular to the direction of airflow through the orbiter's underside, reducing heat in between heat tiles and in the boundary layer between the heat tiles and surrounding air, while helping maintain a laminar airflow through the orbiter.^[74][73]

Crew cabinEdit

The cabin is an all-metal, welded, pressurised compartment housing the crew’s workplaces, control and life support systems. It has three decks. The Command Module on the upper deck is the workspace for the crew and serves to accommodate the commander, pilot, engineer and mission specialist's seats, as well as the RMS operator's workplace. The middeck houses life support and auxiliary equipment, and up to six crewmembers could be seated there during launch and reentry. The lower deck houses the power systems.^[77] The cockpit is similar in layout to that of the space shuttle, with three cathode-ray tube displays.^[78]

Docking systemEdit

The docking module (Стыковочный модуль) is mounted into the forward part of the payload bay. It is a spherical compartment with a diameter of 2.67 m (8.8 ft), with a cylindrical tunnel leading to the androgynous peripheral docking unit (APAS-89). Unlike the U.S. Space Shuttle, the docking compartment for Buran features an extendable tunnel to increase clearance between orbiter and station. Another hatch, facing into the payload bay, was to support extravehicular activity from the orbiter.^[79]

Remote manipulatorEdit

The Onboard Manipulator System (Система Бортовых Манипуляторов), similar to the Space Shuttle's RMS, was developed at the Central Research and Development Institute for Robotics and Technical Cybernetics to support operations with payload. It could be operated both in manual and automatic modes. Buran-class orbiter could carry, depending on the mission, one or two manipulator arms.^[79][80][81]

Laboratory modulesEdit

To expand Buran's capabilities, pressurised modules similar to ESA's Spacelab were designed based on the 37K design. These modules had to be both compartments to conduct experiments and logistics volume, could be mounted either in the payload bay and connected to the crew cabin via tunnel or be temporarily docked to Mir's Kristall side docking port. On Buran's maiden flight, the Accessory Unit (Блок Дополнительных Приборов) 37KB No.37070 was installed into the orbiter's payload bay. It carried recording equipment and accumulators providing power to onboard systems as the regular fuel cells based power system were not ready at the time. The second unit, 37KB No.37071 was built in 1987. It was planned to build a third unit, 37KB No.37072, but this never happened because of programme cancellation.^[82]

PropulsionEdit

Orbital maneuvering is provided by the Joint Propulsion System (Объединенная двигательная установка).^[83]

SpecificationsEdit

The mass of the Buran vehicle is quoted as 62 tonnes,^[84] with a maximum payload of 30 tonnes, for a total lift-off weight of 105 tonnes.^[85][86]

Mass breakdown

• Mass of Total Structure / Landing Systems: 42,000 kg (93,000 lb)
• Mass of Functional Systems and Propulsion: 33,000 kg (73,000 lb)
• Maximum Payload: 30,000 kg (66,000 lb)
• Maximum lift-off weight: 105,000 kg (231,000 lb)

Dimensions

• Length: 36.37 m (119.3 ft)
• Wingspan: 23.92 m (78.5 ft)
• Height on Gear: 16.35 m (53.6 ft)
• Payload bay length: 18.55 m (60.9 ft)
• Payload bay diameter: 4.65 m (15.3 ft)
• Wing glove sweep: 78 degrees
• Wing sweep: 45 degrees

Propulsion

• Total orbital maneuvering engine thrust: 17,600 kgf (173,000 N; 39,000 lbf)
• Orbital Maneuvering Engine Specific Impulse: 362 seconds (3.55 km/s)
• Total Maneuvering Impulse: 5 kgf-sec (11 lbf-sec)
• Total Reaction Control System Thrust: 14,866 kgf (145,790 N; 32,770 lbf)
• Average RCS Specific Impulse: 275–295 seconds (2.70–2.89 km/s)
• Normal Maximum Propellant Load: 14,500 kg (32,000 lb)

Unlike the US Space Shuttle, which was propelled by a combination of solid boosters and the shuttle orbiter's own liquid-fuel engines fueled from a large fuel tank, the Soviet/Russian shuttle system used thrust from the rocket's four RD-170 liquid oxygen/kerosene engines developed by Valentin Glushko and another four RD-0120 liquid oxygen/liquid hydrogen engines.^[87]

Buran and the US Space ShuttleEdit

Comparison to NASA's Space ShuttleEdit

Because Buran's debut followed that of Space Shuttle Columbia's, and because there were striking visual similarities between the two shuttle systems—a state of affairs which recalled the similarity between the Tupolev Tu-144 and Concorde supersonic airliners—many speculated that Cold War espionage played a role in the development of the Soviet shuttle. Despite remarkable external similarities, many key differences existed, which suggests that, had espionage been a factor in Buran's development, it would likely have been in the form of external photography or early airframe designs. One CIA commenter states that Buran was based on a rejected NASA design.^[88] See the § Programme development section above.

Key differences between Buran and NASA's Space ShuttleEdit

• Buran had no main engines; take off and ascent trajectory were accomplished with the Energia rocket whose four main engines were expendable. The three Space Shuttle main engines were part of the orbiter, and were reused for multiple flights.
• The core Energia rocket was equipped with its own guidance, navigation, and control system – unlike Space Shuttle whose entire control system was in the orbiter.
• Unlike Space Shuttle's boosters, each of Energia's four boosters had their own guidance, navigation, and control system, which allowed them to be used as launch vehicles on their own to deliver smaller payloads than those requiring the complete Energia-Buran system.
• Energia could be configured with four, two or no boosters for payloads other than Buran, and in full configuration was able to put up to 100 metric tons into orbit. The Space Shuttle orbiter was integral to its launch system and was the system's only payload.
• Energia's four boosters used liquid propellant (kerosene/oxygen). The Space Shuttle's two boosters used solid propellant.^[89]
• The liquid fueled booster rockets were not constructed in segments vulnerable to leakage through O-rings, which caused the destruction of Challenger.
• The Energia rocket was not covered in foam, the shedding of which from the large fuel tank led to the destruction of Columbia. However, this enabled the risk of shedding ice chunks from the rocket instead.
• Energia's four boosters were designed to be recovered after each flight, though they were not recovered during Energia's two operational flights. The Space Shuttle's boosters were recovered and reused.
• Buran's equivalent of the Space Shuttle Orbital Maneuvering System used GOX/LOX/Kerosene propellant, with lower toxicity and higher performance (a specific impulse of 362 seconds (3.55 km/s) using a turbopump system)^[90] than the Shuttle's pressure-fed monomethylhydrazine/dinitrogen tetroxide OMS engines.
• Buran was designed to be capable of both piloted and fully autonomous flight, including landing. The Space Shuttle was later retrofitted with automated landing capability, first flown 18 years after the Buran on STS-121, but the system was intended to be used only in contingencies.^[91]
• The nose landing gear was located much farther back on the fuselage rather than just under the mid-deck as with the NASA Space Shuttle.
• Buran could lift 30 metric tons into orbit in its standard configuration, comparable to the early Space Shuttle's original 27.8 metric tons^[92][93]
• Buran could return 20 tons from orbit,^[74][94] vs the Space Shuttle's 15 tons.
• Buran included a drag chute, the Space Shuttle originally did not, but was later retrofitted to include one.
• The lift-to-drag ratio of Buran is cited as 6.5,^[95] compared to a subsonic L/D of 4.5 for the Space Shuttle.^[96]
• Buran and Energia were moved to the launch pad horizontally on a rail transporter, and then erected and fueled at the launch site.^[97][98][99] The Space Shuttle was transported vertically on the crawler-transporter with loaded solid boosters but the main tank was fueled at launch site.^[100]
• Buran was intended to carry a crew of up to ten, the Shuttle carried up to eight in regular operation and would have carried more only in a contingency.^[93][101]
• Buran has a different carbon-carbon heat tile layout in its underside,^[74] in which all gaps between heat tiles are parallel or perpendicular to the direction of airflow through the orbiter.^[73]

• MAKS (spacecraft) - Soviet air-launched spaceplane concept
• Mikoyan-Gurevich MiG-105 – Soviet spaceplane test programme
• Space Shuttle programme - American spaceplane programme
• Tupolev OOS - Soviet air-launched spaceplane concept

• Hendrickx, Bart & Vis, Bert (4 October 2007). Energiya-Buran: The Soviet Space Shuttle. Springer-Praxis. doi:10.1007/978-0-387-73984-7. ISBN 978-0-387-69848-9.

• Buran.ru, official website by NPO Molniya
• Buran at Encyclopedia Astronautica
• Buran and Energia at Buran-Energia.com
• Buran at RussianSpaceWeb.com
• Buran: The Soviet Space Shuttle Success Story at TASS (in English)