Buran (spacecraft)

Soviet winged orbital vehicle
the cruise missile

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".

The Buran orbiter is built around the airframe, which is its main structural component, since all other components 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°.

Buran orbiters have their exterior covered in 38,600 heat shielding tiles designed to withstand 100 reentries, 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. 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 around the orbiter. The cockpit is similar in layout to that of the space shuttle, with three cathode ray tube displays.

The docking module (label=none) is mounted into the forward part of the payload bay. It is a spherical compartment with a diameter of , 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.

The Onboard Manipulator System (label=none), 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.

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, 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 (label=none) 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.

Orbital maneuvering is provided by the Joint Propulsion System (label=none).

The automatic landing system is capable of performing a fully automatic descent, approach and landing from any point located in the "admissible starting conditions area" at altitude, controlling the orbiter's flight during the descent. Covering during the approach and eventually slowing down from to zero. The first Buran flight was notable for the automatic landing system electing to perform an unlikely (estimated 3% probability) manoeuvre at the 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 and gusting up to at ground level.

The only orbital launch of a Buran class orbiter, 1K1 (1К1: first orbiter, first flight 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, 206 minutes after launch. Under a crosswind of , Buran landed laterally and 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. Although the Buran programme was never officially cancelled, the dissolution of the Soviet Union led to funding drying up and this flight never took place.