Buran (spacecraft)

Buran (Буран,, meaning "Snowstorm" or "Blizzard"; GRAU index serial number: 11F35 1K, construction number: 1.01) was the first spaceplane to be produced as part of the Soviet/Russian Buran program. Buran completed one uncrewed spaceflight in 1988, and was destroyed in 2002 due to the collapse of its storage hangar. The Buran-class orbiters used the expendable Energia rocket, a class of super heavy-lift launch vehicle. Besides describing the first operational Soviet/Russian shuttle orbiter, "Buran" was also the designation for the entire Soviet/Russian spaceplane project and its flight articles, which were known as "Buran-class orbiters".

Construction
The construction of the Buran spacecraft began in 1980, and by 1984 the first full-scale orbiter was rolled out. Over 1000 companies all over the Soviet Union were involved in construction and development. The Buran spacecraft was made to be launched on the Soviet Union's super-heavy lift vehicle, Energia. The Buran program ended in 1993.

Technical description
The Buran orbiter was built around the airframe, which was its main structural component, since all other components were attached to it. The components necessary for flight made up about 20% of the weight of the orbiter, while another 11% of weight was added by payload systems and removable parts. The wings of the orbiter contained elevators which could be deflected from +35° to −20°.

Exterior
The lower surface of the Buran orbiter was covered in 38,600 carbon-carbon heat shielding tiles designed to withstand 100 reentries. These tiles were very similar to the ones on the US Space Shuttle. The tiles had an antioxidant molybdenum disilicide coating. The black coating in the tiles helped dissipate heat, and, similarly to the tiles used in the Space Shuttle, the Buran tiles were glued to the orbiter. The sides of the heat tiles facing the orbiter were left uncoated to equalize the material pressure with the surroundings, preventing additional mechanical loads. There were deliberate gaps between tiles to allow for thermal expansion. The gaps were filled with quartz fiber, rope, alkaline elements, inserts and brush seals, and the tiles were also waterproofed.

The Buran and Space Shuttle orbiters were exposed to similar temperatures, and both had similar levels of insulation. Compared to the Space Shuttle, Buran had a different tile layout on its underside, in which all gaps between heat tiles are parallel or perpendicular to the direction of airflow through the orbiter's lower surface. This layout was designed to reduce heat in between tiles, and in the boundary layer between the tiles and the atmosphere, while helping maintain a laminar airflow around the orbiter.

Crew module
The crew module was an all-metal, welded, pressurised compartment housing the crew's workplaces, control, and life support systems. It had three decks. The flight deck, known as the Command Compartment (KO), was the workspace for the crew and served to accommodate the commander, pilot, engineer and mission specialist's seats, as well as the operator of the Onboard Manipulator System. The middeck or Habitation Compartment (BO), served as the living and sleeping quarters for the crew. It contained lockers, a galley, sleeping bags, and a toilet, in addition to three instrument bays with radio equipment and thermal control systems. Up to six crew members could be seated in the middeck during launch and reentry. The lower deck, known as the Aggregate Compartment (AO) housed the life support system, the power supply systems and parts of the thermal control system. The cockpit was similar in layout to that of the space shuttle, with three CRT displays.

Docking system
The docking module (Стыковочный Модуль) was mounted into the forward part of the payload bay. It was a spherical compartment with a diameter of 2.67 m, with a cylindrical tunnel leading to the androgynous peripheral docking unit (APAS-89). Unlike the Space Shuttle, the docking compartment for Buran featured an extendable tunnel to increase clearance between orbiter and station. Another hatch, facing into the payload bay, was designed to support extravehicular activities.

Remote manipulator
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. The orbiter could carry, depending on the mission, one or two manipulator arms.

Laboratory modules
To expand Buran 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, and could be mounted either in the payload bay and connected to the crew cabin via tunnel, or be temporarily docked to Mir's Kristall radial docking port. On Buran 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 the cancellation of the program.

Propulsion
Orbital maneuvering was provided by the Joint Propulsion System (Объединенная Двигательная Установка).

Automatic landing system
The automatic landing system was capable of performing a fully automatic descent, approach and landing from any point located in the "admissible starting conditions area" at 100 km altitude, controlling the orbiter's flight during the descent. The descent profile covered 8000 km through the atmosphere during the approach and eventually slowed down from 28000 km/h to zero.

The first Buran flight was notable for the automatic landing system electing to perform an unlikely (estimated 3% probability) manoeuvre at the 20 km key point, which was needed to extend the glide distance and bleed excessive energy. The standard approach was from the south and consisted of two left turns onto the final approach course. Instead, it performed additional turns in both directions and overflew the field to its northern side, before making a right turn back onto the final course. The landing system elected to perform the manoeuvre as the orbiter's energy didn't decrease enough due to strong-gusty winds in the area, measured at 15 m/s and gusting up to 20 m/s at ground level.

Specifications
The dry mass of Buran-class orbiters was quoted 62 tonnes, with a maximum payload of 30 tonnes, for a maximum launch mass of 105 tonnes.

Mass breakdown
 * Total mass of structure and landing systems: 42000 kg
 * Mass of functional systems and propulsion: 33000 kg
 * Maximum payload: 30000 kg
 * Maximum liftoff weight: 105000 kg

Dimensions
 * Length: 36.37 m
 * Wingspan: 23.92 m
 * Height on gear: 16.35 m
 * Payload bay length: 18.55 m
 * Payload bay diameter: 4.65 m
 * Wing chine sweep: 78 degrees
 * Wing sweep: 45 degrees

Propulsion
 * Total orbital manoeuvring engine thrust: 17600 kgf
 * Orbital manoeuvring engine specific impulse: 362 isp
 * Total manoeuvring impulse: unknown
 * Total RCS thrust: 14866 kgf
 * Average RCS specific impulse: 275 - 295 isp
 * Normal maximum propellant load: 14500 kg

Unlike the US Space Shuttle, which was propelled by a combination of solid boosters and the orbiter's own liquid-propellant engines fuelled from a large tank, the Soviet/Russian Energia launch system used thrust from each booster's RD-170 liquid oxygen/kerosene engine (each with four nozzles), developed by Valentin Glushko, and another four RD-0120 liquid oxygen/liquid hydrogen engines attached to the central block.

Orbital flight
The only orbital launch of a Buran-class orbiter, 1K1 (1К1: first orbiter, first flight ) occurred at 03:00:02 UTC on 15 November 1988 from Baikonur Cosmodrome launch pad 110/37. Buran was lifted into space, on an uncrewed mission, by the specially designed Energia rocket. The automated launch sequence performed as specified, and the Energia rocket lifted the vehicle into a temporary orbit before the orbiter separated as programmed. After boosting itself to a higher orbit and completing two orbits around the Earth, the ODU (Объединенная Двигательная Установка) engines fired automatically to begin the descent into the atmosphere, return to the launch site, and horizontal landing on a runway.

After making an automated approach to Site 251, Buran touched down under its own control at 06:24:42 UTC and came to a stop at 06:25:24, 206 minutes after launch. Under a crosswind of 61.2 km/h, Buran landed 3 m laterally and 10 m longitudinally from the target mark. It was the first spaceplane to perform an uncrewed flight, including landing in fully automatic mode. It was later found that Buran had lost eight of its 38,000 thermal tiles over the course of its flight.

Projected flights
In 1989, it was projected that Buran would have an uncrewed second flight by 1993, with a duration of 15–20 days. However, the dissolution of the Soviet Union led to funding drying up and the Buran programme was officially cancelled in 1993.