Category Energiya-Buran

A SLOW RESPONSE

Early work on the Space Shuttle in the late 1960s did not spark an immediate response from the Soviet side for a number of reasons. The only two design bureaus capable of building manned spacecraft had more pressing concerns. TsKBEM, the former Korolyov design bureau (now headed by Vasiliy Mishin), was preoccupied with Soyuz, the civilian DOS space station, and the N-1/L-3 manned lunar program. TsKBM, the Chelomey design bureau, was busy working on the military Almaz space station and its TKS transport ship, not to mention a variety of unmanned military satellites and anti-ship missile projects.

Not only would the development of a large reusable spacecraft place an extra burden on the already overtaxed design bureaus, there simply was no clear need for such a system in the near future. The Soyuz and TKS spacecraft could perfectly handle transportation tasks for the DOS and Almaz stations and the Soviet Union had a varied fleet of expendable rockets to satisfy satellite launch requirements for many years to come.

Looking at the more distant future, TsKBEM was studying a so-called Multi­purpose Orbital Complex (MOK), an entire orbital infrastructure aimed at lowering space transportation costs. Even here there was no immediate need for a large reusable shuttle system. The centerpiece of the MOK was to be a giant N-1 launched space station called MKBS (Multipurpose Space Base Station) that would serve as an orbiting garage. The idea was that satellites in the constellation would be serviced either at the MKBS or regularly be visited by MKBS-based crews flying light versions of the Soyuz outfitted with a manipulator arm. The satellites themselves would be orbited by expendable rockets or partially reusable rockets based on the N-1. In April 1972 Mishin and Chelomey got approval for a joint proposal to turn Almaz into a combined civilian/military space station serviced by Soyuz spacecraft, allowing TsKBEM to focus on the more distant goal of creating the MOK. The two chief designers agreed that Chelomey’s TKS would be the MOK’s key transportation

system during the program’s experimental phase. Reusable transportation systems were part of the MOK plans, but only at a later stage [2].

There were also other obstacles to the initiation of a Space Shuttle type project. Requiring a blend of aviation, rocket, and space technology, it would be an organ­izational nightmare. The leading missile and space design bureaus, including TsKBEM and TsKBM, came under the “space and missile industry’’ known as the Ministry of General Machine Building (MOM) (headed by Sergey Afanasyev), while the leading aviation design bureaus were under the Ministry of the Aviation Industry (MAP) (headed by Pyotr Dementyev). Although both were willing to participate in such an effort, neither was eager to take on prime responsibility for it, considering it to be “the other ministry’s field of business’’.

Finally, the atmosphere around the turn of the decade may not have been conducive to the start of a totally new program. It was a period marked by many spectacular failures in the Soviet space program, both launch vehicle mishaps (notably the Proton and the N-l) and spacecraft malfunctions (notably lunar and deep-space probes). The string of failures even led to the creation of an investigative commission, which concluded that one of the root causes for the numerous setbacks was the lack of proper ground-testing facilities such as engine test stands, vacuum chambers, and the like. Embarking on a completely new, costly, and technologically advanced project under such conditions would not have been a logical course of action.

However, while any final decision on a Soviet shuttle was still years away, some in the Soviet space community did think it was time to begin preliminary research on such a system. The initiative seems to have come from the Military Industrial Commission (VPK), a body under the Council of Ministers (the Soviet government) that oversaw all defense-related ministries (including MOM and MAP). Among its tasks was to formulate new proposals for military and space projects (with the necessary input from the design bureaus and the military community), which could then be officially approved in the form of joint decrees of the Central Committee of the Communist Party and the Council of Ministers. These decrees would set rough timelines for projects, outline their major goals, and also assign the main organiza­tions that would be involved. It was then again up to the VPK to implement those decrees by dividing the work among the design bureaus, setting concrete timetables, and convening meetings of the people in charge.

In a draft proposal for the Soviet Union’s next five-year space program dated 27 November 1970, the VPK suggested that both MOM and MAP as well as other organizations should work out a so-called “draft plan’’ for a “unified reusable transport ship’’ in 1972. This is the first known written evidence of the Soviet Union’s intention to respond to the Space Shuttle. Essentially, it was an order to produce nothing more than paperwork. The “draft plan’’ is just one of the preliminary stages that Soviet space projects went through before metal was actually cut.

Indications are that the phrase about the reusable transportation system was not included in the final government and party decree describing the country’s goals in space for the next five years. Clearly, the time was not quite ripe enough even for preliminary research on a shuttle system. There may have been opposition from

MOM and MAP but, perhaps more importantly, there was no urgent need to begin this work because the US Space Shuttle had not even been officially approved.

Even President Nixon’s go-ahead for the Space Shuttle project in January 1972 did not set in motion a concerted effort to develop a reusable spacecraft. The first high-level meeting in response to Nixon’s January 1972 announcement was organized by the VPK on 31 March 1972. It was attended by both industry and military officials, more particularly representatives of TsNIIMash (MOM’s leading space test and research facility), the TsNII-30 and TsNII-50 military research institutes, the Chief Directorate of Space Assets or GUKOS (the “space branch’’ of the Strategic Rocket Forces) and the Air Force, but no consensus was reached on the need for a response. At this stage the VPK once again formulated a draft proposal asking MOM, MAP, and other organizations to develop a draft plan for a shuttle system, but it met with stiff opposition from MOM minister Afanasyev and was not accepted.

In late April 1972 another meeting took place at TsNIIMash, attended by some of the chief designers (Mishin, Chelomey, Glushko), officials of MOM and TsNII-50. Their conclusion was that a reusable space transportation system was a less efficient and less cost-effective way of delivering payloads to orbit than expendable boosters. Also, they did not see an immediate need for using such a system to return satellites or other hardware back to Earth, certainly not after Mishin and Chelomey had received approval for the MOK/TKS plan that same month. Moreover, at this point the US Space Shuttle was not considered a military threat to the Soviet Union [3].

Tiles

Buran was covered with approximately 38,800 heat-resistant tiles (compared with nearly 31,000 tiles on Columbia for STS-1). Each tile consisted of a substrate and a coating. The substrate came in two types with different densities. One was called TZMK-10 (with a density of 0.15g/cm3) and the other TZMK-25 (density 0.25 g/cm3). These were more or less comparable in characteristics and performance with the two basic types of Shuttle tile substrate (Li-900 and Li-2200). They were used in regions where Buran was exposed to temperatures of anywhere between 700°C and 1,250°C. The tiles were made of high-purity 98-99 percent amorphous silica fibres derived from common sand (SiO2—silica) with minimum amounts of natrium, potassium, and calcium oxides to lower the melting point of the fibers. The thickness of the tiles depended on where they were attached to the aluminum skin and the temperatures and aerodynamic stresses that any particular part of Buran was exposed to.

Both the TZMK-10 and 25 had special 0.3 mm thick glass coatings to reject heat and protect the tiles against wind loads and moisture penetration. This was very

Thermal protection 111

Post-flight picture of black and white tiles near Buran’s entry hatch. Note “smearing” of some tiles (B. Vis).

similar to the Reaction-Cured Glass (RCG) coating on the Shuttle’s tiles. Chemicals were added to the coating to give the tiles different colors and heat rejection cap­abilities. Black coating (both for TZMK-10 and 25) was mainly needed to protect the underside of Buran against the high temperatures of re-entry, with the higher-density TZMK-25 only being used in regions exposed to the highest stresses. The black – coated tiles on the belly could not be permanently exposed to sunlight for more than 6 hours. White coating (only applied to TZMK-10) mainly served the purpose of protecting the upper surfaces of the vehicle against solar radiation in orbit.

Although the coating provided some protection against moisture penetration, any cracks in the coating would easily let moisture through. Therefore, additional measures had to be taken to make the tiles waterproof. During manufacture the tiles were treated with a special silicon polymer solution, but that burned out during the first flight in all areas where temperatures exceeded +450° C. Therefore, the tiles would have needed to be rewaterproofed for any subsequent missions (had they been flown). For that purpose the Russians developed a varnish-like coating as well as a technique to permeate the tile with a substance known as hexamethyl disilazane. NASA uses a similar substance (dimethylethoxysilane) for rewaterproofing Shuttle tiles, but injects the material into the tiles, whereas the Russians planned to use a gas diffusion technique.

Since the fragile tiles could not withstand structural deflections and expansions of the aluminum skin, they were not attached directly to the skin, but to 4 mm thick felt

Buran sitting atop Mriya at the Paris Air Show in 1989. Square-shaped ATM-19PKP panels are visible on the mid fuselage (surrounding the name “Buran”) and on the upper portions of the payload bay doors (source: Luc van den Abeelen).

pads, which then in turn were bonded to the actual skin. Similar to the Shuttle’s Strain Isolation Pads, they were attached to the tiles as well as to the skin of Buran with an adhesive based on silicon rubber, ensuring a reliable bond in a temperature range of -130°C to +300°C.

Since the tiles thermally expanded or contracted very little, small gaps were left between them to permit relative motion and allow for the deformation of the alum­inum structure under them due to thermal effects. The gaps were filled with a special felt-type material based on organic fibers and capable of withstanding temperatures of up to 430° C.

Tests showed that, if a tile was lost but the underlying felt pad remained in place, the temperature of the aluminum skin would not reach its 500°C melting point, even in areas where temperatures reached 1,250° C. If the felt pad was also lost, there could be damage to the skin, but only in regions close to where carbon-carbon panels were used.

About 28,000 of the tiles were trapezoidal in shape with sizes ranging from about 150 x 150 mm to 200 x 200 mm. Approximately 6,000 tiles were irregular and formed complex patterns on the hatches, around the nozzles of the engines, and on certain edges. Approximately 4,800 tiles had even more complex shapes. Although the distribution of black and white tiles over Buran’s surface was very similar to that on the Orbiter, there were different layout patterns. A fan-type pattern was used on the nose section, elevons, and the vertical stabilizer to avoid the use of triangular and sharply angular tiles of low strength.

Early Return

“Early Return” was a scenario giving the crew 3 to 24 hours to prepare for deorbit, with a much better chance of reaching one of the three runways. This would have required the same type of action on the part of the crew as “Immediate Return”, but only at a more relaxed pace. The most probable event leading to such a situation would have been a dangerous loss of redundancy in critical on-board systems such as the computers, the GSP gyro platforms, the fuel cells, etc. Even depressurization of the crew cabin was ranked as an anomaly that would give the crew several hours or more to prepare for deorbit, assuming that the loss of pressure was slow enough for the crew to have a chance to don their Strizh pressure suits and hook them up to the Personal Life Support System (the minimum time required for this was five minutes). Cabin systems were designed to operate in a vacuum and the suit’s life support systems could sustain the crew for 12 hours.

CREWING FOR BURAN’S FIRST MANNED MISSIONS

Soviet planners envisaged an extensive orbital test flight program for Buran, which at one point included as many as 10 missions, both unmanned and manned. By comparison, the US Space Shuttle flew just four (manned) test flights in 1981— 1982 before being declared operational.

For safety reasons, crews for the initial Buran test flights would have been restricted to just two cosmonauts. First, it was not practical to install ejection seats for more than two crew members and, second, if a life-threatening emergency arose in orbit, a Soyuz would have to be able to come to the rescue. Since that Soyuz needed a “rescue commander”, only two seats would be left in the vehicle for the stranded Buran crew.

Throughout the 1980s, there was disagreement on the composition of the initial Buran crews. LII in Zhukovskiy, backed by the Air Force, argued that both seats should be occupied by its experienced test pilots. However, NPO Energiya, intent on not being sidelined, pushed to fly one of its engineers in the co-pilot seat rather than an LII test pilot. Therefore, two types of crews were considered for most of the duration of the program: crews consisting of two LII pilots, on the one hand, and crews composed of one LII pilot and one NPO Energiya flight engineer, on the other hand.

It should be stressed that as Buran never came anywhere close to flying a manned mission, none of the crews mentioned below was ever officially assigned. The flight plan for the first manned mission remained vague until the end of the program and none of these crews performed any dedicated mission training.

LII crews

From the very beginning LII had the following crews in mind for the first flight:

Prime crew Back-up crew

Igor Volk Anatoliy Levchenko

Rimantas Stankyavichus Aleksandr Shchukin

The preference for Volk-Stankyavichus and Levchenko-Shchukin was reflected in the fact that the two crews flew the bulk of the atmospheric Horizontal Flight Tests with the BTS-002 Buran analog. A total of 24 such flights were performed between November 1985 and April 1988. Volk and Stankyavichus were paired for 11 of the missions and Levchenko and Shchukin jointly flew 4 missions (see Chapter 6).

The original crewing plan was completely disrupted in August 1988, when in a bizarre twist of fate Buran lost its entire back-up crew with the deaths of both Levchenko and Shchukin. As a result, Volk and Stankyavichus were split up and both got new co-pilots from the LII ranks [41]. Volk has claimed that GKNII pilots Ivan Bachurin and Aleksey Boroday, veterans of six BTS-002 flights, were also considered as the back-up crew [42]. The new crews were:

Prime crew Back-up crew

Igor Volk Rimantas Stankyavichus

Magomed Tolboyev Viktor Zabolotskiy

Internal LII documents show that another option considered was to retain the Volk- Stankyavichus team, with Zabolotskiy and Tolboyev acting as back-ups. This plan assumed that Zabolotskiy would first fly a Soyuz mission to give him the necessary spaceflight experience to command Buran if the need arose [43].

When Stankyavichus was killed in a plane crash in September 1990, LII was forced once again to change the composition of the back-up crew [44]. The new crews were:

Prime crew Back-up crew

Igor Volk Viktor Zabolotskiy

Magomed Tolboyev Ural Sultanov

These are the last crews known to have been considered by LII for the first piloted Buran mission.

Snooping on Buran

Although the Energiya-Buran program remained shrouded in secrecy for much of the 1980s, US intelligence specialists had a fairly good idea of the system’s character­istics and capabilities, mainly thanks to detailed American reconnaissance satellite images of both Baykonur and the Flight Research Institute (LII) in Zhukovskiy. The latter was identified in the intelligence literature as Ramenskoye, which is the name of LII’s airfield in Zhukovskiy and (confusingly) also of a neighboring town and railway station.

The first clear evidence for the existence of a large shuttle came in the late 1970s, when construction of the runway and launch pads at Baykonur got underway. The Energiya-Buran pads were identified as “Complex J’’ (the same code name given to the N-1 pads) and the UKSS pad as “Complex W’’. By 1982 spy satellites had even spotted the construction of the back-up runway in the Soviet Far East. [14].

The first public assessment of the system’s capabilities was given in Soviet Military Power 1983, published in early 1983. Since the first test models of Energiya were yet to be rolled out to the pad, analysts still had a poor understanding of the system’s configuration and capabilities. Drawings showed the Soviet shuttle mounted on an external tank with two rocket boosters, with the main engines apparently on the orbiter itself. The lift-off weight of the system was estimated to be just 1,500 tons compared with the NASA Shuttle lift-off weight of 2,220 tons. Combined with an estimated lift-off thrust of between 1,800 and 2,700 tons (compared with roughly 3,000 tons for the Shuttle), this translated into a staggering payload capacity of 60 tons, twice that of the Space Shuttle Orbiter. The Soviet shuttle was believed to have a substantially different wing design with an 80-degree sweep. The heavy-lift launch vehicle (HLLV) was depicted as a 95 m high core vehicle with three 35 m high liquid propellant boosters and a top-mounted payload with a maximum mass of between 130 and 150 tons [15].

Assessment of Soviet heavy-lift launch vehicle capabilities in Soviet Military Power 1983 {source: US Department of Defense).

By the middle of 1983 several events led to a much better understanding of the Soviet shuttle system. Spy satellites had acquired detailed images of a test orbiter sitting atop a VM-T carrier aircraft during tests earlier in the year and had also spotted an incident in which the pair accidentally skidded off the runway in March 1983. Moreover, the first test versions of Energiya had been rolled out of the assembly building in the first half of the year. A CIA National Intelligence Estimate in July 1983 now correctly concluded that the orbiter had a configuration very similar to that of the US Space Shuttle Orbiter and that the main engines were on the core rather than on the orbiter. The report was wrong in stating that the rocket had only two strap-on boosters and that the core was outfitted with “at least two and probably three engines”. This may have been related to the fact that the Energiya rolled out in May 1983 had only three nozzles installed on the core stage {see Chapter 6). The report referred to the spherical sections above the core stage nozzles as “pod-like

US Defense Department representation of Soviet shuttle on the pad. Illustration from Soviet Military Power 1986 (source: US Department of Defense).

objects” that were erroneously interpreted as part of a recovery system for the LOX/LH2 engines [16]. In Soviet Military Power 1984 lift-off weight and thrust were now estimated at 2,000 tons and 3,000 tons, respectively, resulting in an orbiter payload capacity of 30 tons. The HLLV was still expected to be a nearly 100 m high rocket with six or more strap-on boosters and a payload capacity of 150 tons, a configuration that was actually more reminiscent of the Vulkan rocket.

It was not until the 1986 edition that Soviet Military Power published a drawing of a 100-ton capacity HLLV where the orbiter was replaced by a side-mounted cargo pod. This was also the first edition that got the dimensions of the rocket/orbiter stack more or less right, although the first Energiya-Buran combination did not make its appearance on the Baykonur launch pads until summer/autumn of 1986, after the report had been published. The following year potential payloads for the cargo version of the rocket were said to be modules for large space stations, components for a manned or unmanned interplanetary mission, and even directed-energy ASAT and ballistic missile defense weapons.

Reconnaissance satellite images of Baykonur also gave some idea of how the testing proceeded. In 1984 and early 1985 the SL-X-16 (“Zenit”) medium-lift booster had been observed being alternately removed from and erected on the pad, suggesting Soviet dissatisfaction with the ground test results. This in turn had implications for

US Defense Department representation of Soviet shuttle atop the VM-T aircraft. Illustration from Soviet Military Power 1985 (source: US Department of Defense).

the HLLV/shuttle program, which used common engines. Apparently, the belief at this time was that the SL-X-16 was powered by liquid hydrogen/liquid oxygen engines and that these same engines were used both in the strap-ons and the core stage of the HLLV. The fact that no Energiya had yet been seen with an orbiter strapped to the side was also seen as an indication that the program was suffering delays [17]. When a test orbiter did finally undergo the first pad tests in August – October 1986, the news was reported only weeks later [18]. US reconnaissance assets apparently also picked up signs of the Energiya core stage test firings in the first half of 1986, but these were not openly reported until a year later [19].

Buran-related test activities were not always correctly interpreted, especially when the Soviet approach to testing was different than NASA’s. Just weeks before the first ground run of the BTS-002 atmospheric test bed at LII in late December 1984, Aviation Week correctly reported that approach and landing tests of the shuttle were imminent, but wrongly concluded that the vehicle would be dropped from the VM-T carrier aircraft in similar fashion to the test flights of Enterprise in 1977 [20]. In April 1986, by which time BTS-002 had performed numerous ground runs and two

landing tests, Aviation Week referred to reconnaissance photography showing jet engines mounted on either side of the tail, but still believed the vehicle was being dropped from the VM-T. The jet engines were thought to be on board only to test their ability to correct an orbiter’s flight path when returning from space and might or might not be lit prior to separation from the aircraft depending on test objectives [21].

Of course, the information that leaked out via Aviation Week did not necessarily reflect what the US intelligence community really knew. Other observers, taking into account the known capabilities of the VM-T, correctly concluded that it could hardly carry a full-size, full-weight orbiter to sufficient altitude for a safe free flight [22]. Aviation Week did not report the correct flight profile of the BTS-002 until late 1987 after having been informed by Soviet space officials at an international space congress in Moscow. The only mistake remaining was that the tests were said to take place at Baykonur [23].

Western observers had more to go on than just the intelligence community’s interpretation of reconnaissance satellite imagery. Pictures taken of Baykonur by civilian remote-sensing satellites such as the US Landsat and the French SPOT had sufficient resolution to show the construction work going on in support of the Energiya-Buran program. Unlike the spy satellite pictures, these were openly available to the public.

It is not clear how much information on the program leaked to the West through breaches in the Soviet censorship and security apparatus or via human intelligence. One piece of information that did slip through was that the name of the Soviet shuttle was Buran. The name first appeared in a 1983 CIA National Intelligence Estimate and also surfaced in several open Western publications the following years, well before the Russians officially announced it [24]. This information could not possibly have been gleaned from spy satellite photography, because the name was not on any of the test models and was not painted on the first flight vehicle until 1988. Actually, before 1988 Buran was not the name of a specific orbiter, but a generic name used by the Russians to refer to the combination of rocket and orbiter (see Chapter 2).

Cargo Transport Container

For cargo missions the orbiter would have been replaced by a so-called Cargo Transport Container (GTK or 14S70) that could house a variety of payloads. This configuration was known as Buran-T (T standing for “transport”) before the name Energiya was adopted in 1987. The interfaces between the rocket and the payload would have been virtually identical to those on Energiya-Buran. Two diameters were considered for the GTK—namely, 5.5 m and 6.7 m—with the final choice falling on the latter, which turned out to be the most favorable in terms of aerodynamic and other characteristics. The container was 42 m long and had an internal volume of about 1,000 m3. The two main sections of the container were to be jettisoned after the rocket passed through the thickest layers of the atmosphere. The GTK was not used on the maiden flight of Energiya with the Skif-DM/Polyus payload, which flew the launch profile unprotected, except for a shroud on the upper FSB section. Strictly speaking, this was not a standard Buran-T configuration [56].

The Soviet response to NASP

Research on aerospace planes in the Soviet Union got a fresh impetus in the mid-1980s, presumably in response to similar work started in the US in 1982 at the Defense Advanced Research Projects Agency (DARPA) under the name Copper Canyon and then transferred to NASA and the Air Force as the National Aerospace Plane (NASP) in 1986. President Ronald Reagan mentioned the project in his State of the Union speech on 4 February 1986, calling it:

“a new Orient Express that could, by the end of the next decade, take off from Dulles Airport, accelerate up to 15 times the speed of sound, attaining low Earth orbit or flying to Tokyo within two hours.’’

Although touted by the Reagan Administration for its civilian commercial applica­tions and as a possible follow-on to the Space Shuttle for NASA, the 80-20 split of funding between the Air Force and NASA clearly indicates NASP was first and foremost a military program. The objective of the program was to develop a proto­type SSTO vehicle taking off with turbojets, then switching to hydrogen-fueled scramjets at subsonic and hypersonic speeds, with a LOX/LH2 rocket engine performing orbit insertion.

The go-ahead for the Soviet response came in two government decrees on 27 January and 19 July 1986, followed by the release of technical specifications by

The Tu-2000.

the Ministry of Defense on 1 September 1986. Three organizations were tasked to come up with proposals: NPO Energiya, the Yakovlev bureau, and the Tupolev bureau. While nothing is known about the Yakovlev concept, NPO Energiya’s aero­space plane was a 71 m long vehicle with a wingspan of 42 m and a maximum height of 10 m. With a take-off mass of approximately 700 tons (dry mass 140 tons), the vehicle would use a combination of turbojets, scramjets, and rocket engines to reach orbit. It was designed for the deployment of payloads into low orbits (at least 25 tons into a 200 km, 51° orbit), servicing of orbital complexes, intercontinental passenger transport and also for military operations “in and from orbit’’. The project was headed by veteran designer Pavel Tsybin [20].

The project eventually selected for further development was the Tupolev bureau’s Tu-2000. Actually, the bureau was no newcomer to SSTO vehicles, having already performed low-priority studies of horizontal take-off and landing space – planes with a take-off mass of up to 300 tons in 1968-1971. Overall Tu-2000 was very similar in design to NASP, relying on the same combination of engines to go into orbit. It had a vertical stabilizer and small delta wings, with much of the lift provided by the flat-shaped underside of the fuselage. A huge hydrogen tank occupied most of the mid and aft fuselage and would feed both the scramjet and rocket engines. The oxygen tank for the rocket engine was located in the tail section.

The Tupolev bureau proposed to carry out the project in two stages. First, it would develop a 55-60 m long two-man suborbital demonstrator (Tu-2000A) to reach a maximum velocity of Mach 5/6 and an altitude of up to 30 km. With a take-off mass between 70 and 90 tons, the vehicle would be equipped with four turbojet engines, two scramjets, and two liquid-fuel rocket engines. Then the project would move on to an experimental 71 m long two-man orbital version with a take-off mass between 210 and 280 tons and six rather than four turbojet engines. Payload capacity was 6-10 tons to low orbits between 200 and 400 km. Unconfirmed reports suggest the Tupolev bureau also planned a long-range bomber (Tu-2000B) and a hypersonic passenger plane based on the Tu-2000 design.

By the early 1990s the Tupolev bureau had reportedly built a wing torque box made of a nickel alloy, elements of the fuselage, cryogenic fuel tanks, and composite fuel lines. Estimates made in 1995 showed that Tu-2000 related R&D would cost at least $5.29 billion, a high price-tag even if Russia had a healthy economy. Budget realities had also forced NASA and the Air Force to cancel NASP in 1993. Although low-level research on the Tu-2000 may have continued for several more years, this project obviously stands no chance of being realized any time soon [21].

CONFLICTING CONFIGURATIONS

By the middle of 1975 two competing designs had emerged within NPO Energiya for a Soviet response to the Space Shuttle. In Glushko’s vision the orbiter would be just one of the payloads for his RLA rockets, mounted on top of the rocket as a conventional payload. If a winged orbiter was going to be mounted atop an RLA booster, it would place very high loads on the core stage, especially during the phase of maximum aerodynamic pressure. Therefore, the core stage would have to be strengthened, making it even heavier than it already was and decreasing the rocket’s payload capacity [52]. Therefore, the top-mounted orbiter would have to be a wing­less, vertical-landing lifting body. This configuration was backed by NPO Energiya luminaries such as Boris Chertok, Yuriy Semyonov, and Konstantin Bushuyev, who were convinced the USSR was not capable of building a reusable space transporta­tion system akin to the Space Shuttle [53]. It would also eliminate some thorny organizational problems, requiring minimal involvement from the Ministry of the Aviation Industry.

Another option under consideration was to mimic the Space Shuttle as closely as possible, namely to build a winged orbiter with main engines which would be strapped to an external fuel tank with strap-on boosters. Known as OS-120, it would enable the Russians to benefit from research and development done in the US and thereby minimize risk. While backed by Igor Sadovskiy, it was Glushko’s nightmare, since this design left no room for the family of launch vehicles he had been dreaming of for many years. The philosophy behind the OS-120 was that the Soviet Union would solely be able to match the US Shuttle’s capability to place 30 tons into orbit and return 20 tons back to Earth and nothing more. After all, the 100 to 200-ton payload capacity of the heavy RLA rockets, mainly needed for establishing lunar bases and staging manned interplanetary missions, was of little interest to the Soviet military.

Orbital maneuvering engines

The two orbital maneuvering engines (Russian acronym DOM, also referred to as 17D12) were a further development of NPO Energiya’s 11D58 engine used in the Blok-D, an upper stage for the Proton rocket and later also employed by Sea Launch’s Zenit-3SL. Each having a vacuum thrust of 8.8 tons and a specific impulse of 362 s, they performed final orbit insertion, orbit circularization, orbit corrections, and the deorbit burn, and were also supposed to be activated in certain launch abort scenarios to burn excess propellant. A long-term objective was to use the DOM engines to provide additional thrust during a nominal launch, a technique that NASA introduced with the Shuttle’s OMS engines on STS-90 in 1998.

Usually, only one of the two was required for any given standard burn, with the other acting as a back-up. Simultaneous ignition of both engines was only required in launch emergencies. The DOM ignition process began with a 20-25 second burn of two primary thrusters to force the LOX and sintin out of their tanks. The engine used a closed-cycle scheme, re-routing the gases used to drive the turbopump to the combustion chamber. During each burn the propellant tanks were pressurized with gaseous helium. In order to save helium, gaseous oxygen was used to pressurize the LOX tank for the deorbit burn. The engine nozzles could be gimbaled up to 6 degrees in two axes (pitch and yaw) for thrust vector control. Each DOM was designed to be ignited up to 15 times during a single mission.

NPO Energiya Volga Branch/Progress

The bulk of the design work on the core stage was performed by a branch of NPO Energiya situated in the city of Kuybyshev (renamed Samara in 1991). Situated on the banks of the Volga river almost 1,000 km east of Moscow, this city is home to some of the most important Russian space-related enterprises. The most famous of these is a design bureau that originated as Branch nr. 3 of Sergey Korolyov’s OKB-1 in 1959. It oversaw the further development of R-7 based rockets and later also designed the lower stages of the N-1 rocket as well as the nation’s photoreconnaissance, biological, and materials-processing satellites. The bureau’s chief Dmitriy Kozlov was asked to design the core stage of NPO Energiya’s new heavy-lift rockets, but turned down the offer, electing instead to focus on ongoing projects.

As a result, Branch nr. 3 became independent as the Central Specialized Design Bureau (TsSKB) on 30 July 1974, with NPO Energiya setting up a new “Volga Branch’’ in Kuybyshev to work on the core stage. Actually, the branch was set up at a time when the Energiya rocket as such did not yet exist and NPO Energiya was still working on its early RLA concepts. Receiving basic parameters from NPO Energiya’s central design bureau in Moscow, a 1,000-man strong team under the leadership of Boris G. Penzin put out all the necessary blueprints for the construction of the core stage. According to one veteran this was so much that “not even two Energiya rockets could lift it off the ground’’. The Volga Branch was also responsible

for designing the Blok-Ya launch table adapter. Penzin retired in 1987 and was replaced by Stanislav A. Petrenko.

Assembly of core stage elements took place at the Progress factory, also situated in Kuybyshev, although that was primarily aligned with Kozlov’s design bureau. The construction of the giant core stage required the construction of several new halls as well as several other facilities, such as chambers for cryogenic tests of the propellant tanks using liquid nitrogen. The Energiya core stage was flown to Baykonur in two separate sections. A branch of the Progress factory was responsible for final core stage assembly and Energiya integration at the Energiya assembly building at Baykonur. The director of Progress for most of the Buran years was Anatoliy A. Chizhov (1980-1997) [6].