Category Energiya-Buran

By 1988, twelve years after the approval of the Energiya-Buran program, the stage was finally set for the Soviet space shuttle to make its orbital debut. While earlier test flights of piloted spacecraft had been prepared in utter secrecy and conveniently disguised under the all-embracing “Kosmos” label, the Russians no longer had the luxury of doing the same with Buran. Times had changed after General Secretary Mikhail Gorbachov’s rise to power in the spring of 1985. The new policy of glasnost was sweeping through all ranks of Soviet society, including the country’s space program.

Disclosing the existence of a Soviet equivalent to the US Space Shuttle in some ways must have been an embarrassing move for the Russians. Not only did the maiden flight of Buran come seven years after the first mission of the Space Shuttle, the Soviet media had always been very critical of the Shuttle program, portraying it as just another tool of the Pentagon to realize its ambition of militarizing space. This tradition began with the very first Shuttle launch on 12 April 1981, which entirely by coincidence overshadowed the 20th anniversary of the mission of Yuriy Gagarin. Reporting on the launch, Radio Moscow World Service said:

“The United States embarked on the Shuttle program some 10 years ago. Its military pin on the program far-reaching hopes for transferring the arms race to space. One of the main missions in the first few flights of the Shuttle will be testing a laser arms guidance system.’’

Even though the Shuttle eventually flew only a handful of dedicated Defense Depart­ment missions, no Shuttle flight went by without the Soviet media reminding the world of the ship’s military potential, the more so after President Ronald Reagan’s announcement of the Strategic Defense Initiative in March 1983. Even when Challenger exploded in January 1986, Radio Moscow warned its listeners that:

“a similar failure in the SDI system the American Administration is so anxious

to create would cause a global disaster” [1].

Many Soviet space officials and cosmonauts had also denounced the Space Shuttle program as a wasteful effort, emphasizing that a fleet of expendable rockets was a much more economical way of delivering payloads to orbit. At the same time, some also stopped short of flatly denying that reusable space transportation systems were being studied, although no technical details or timelines were given. Until 1987 the Energiya-Buran program was a closely guarded state secret, requiring a cover-up operation comparable in scale with that for the Soviet manned lunar program in the 1960s and early 1970s.

However, as had been the case with the N-1 Moon rocket, there was no way the Russians could conceal Buran-related construction work and tests from the all-seeing eyes of US reconnaissance satellites. Long before the Russians opened the informa­tion floodgates, US intelligence had a very good understanding of the system’s configuration and capabilities, although some serious misjudgments were made as well, at least based on what has been declassified so far. Significantly, the information was publicly released on a much wider scale than it had been during the Moon race in the 1960s.

Post-landing operations on the runway included removal of residual LOX from the ODU propulsion system. After that, Buran was wheeled back to the MZK building,

where—among other things—residual kerosene in the ODU system and hydrazine for the Auxiliary Power Units were drained from the vehicle’s tanks. Buran was still in the MZK at the end of the month, when a French delegation headed by President Francois Mitterand visited the cosmodrome to watch the launch of “spationaut” Jean-Loup Chretien aboard Soyuz TM-7 on 26 November.

After Buran was towed back to its MIK OK processing building, engineers got down to a close inspection of the vehicle. Much attention was focused on the ship’s heat shield. Several dozen tiles were damaged, showing cracks or signs of erosion or melting, and seven were lost altogether (compared with sixteen on Columbia during STS-1). These were one black tile each on the vertical stabilizer, rudder/speed brake, and body flap, three black tiles on the underside of the left wing and one white tile near one of the overhead windows. The three black tiles were in an area bordering on one of the reinforced carbon-carbon panels on the leading edge of the wing. This is the only area where the underlying surface suffered major damage, fortunately without catastrophic consequences. There were also two missing blankets of flexible thermal insulation on the upper left wing and several gapfillers were missing on the vehicle’s underside.

With the launch having taken place in cold and wet conditions, much of the damage sustained by the thermal protection system is believed to have been caused by chunks of ice falling from the launch tower, Energiya’s core stage, and the orbiter itself. There was also some significant scorching of tiles on the vertical stabilizer and the aft fuselage of the vehicle. This was attributed not only to the thermal effects of re­entry, but also to exhaust gases impinging on the vehicle from the separation motors of Energiya’s strap-on boosters [57].

Little more has been revealed about post-flight analysis of Buran. Before thorough checks could be completed, the orbiter had to be readied for a series of test flights atop the new Mriya carrier aircraft in May 1989 in preparation for a flight to the Paris Air Show in June 1989 (see Chapter 4). By the time Buran returned to its hangar in Baykonur, there were already growing doubts about the program’s future. Moreover, since the second mission was to be flown by the second orbiter, there was no urgency in preparing Buran for its next flight.

In the mid-1980s NPO Molniya began building three more airframes intended for use in spaceflight-qualified vehicles (3K, 4K, and 5K). Talking about vehicle 3K in early 1990, Gleb Lozino-Lozinskiy said it would be lighter and more reliable than the earlier orbiters thanks to the use of composite materials and an improved thermal protection system. He expected the spacecraft to be ready in 1992 [52].

Actually, vehicle 3K (airframe nr. 2.01) was only about 30 percent ready when the Buran program was canceled in 1993. It consisted of a complete fuselage, but apparently had very few internal systems installed. Pictures of the vehicle show that the crew compartment and the aft compartment were virtually empty. The fuselage was only partly covered with tiles and the payload bay doors were missing. Vehicle 3K remained at the Tushino Machine Building Factory near Moscow until October 2004, when the fuselage, wings, and vertical stabilizer were transported separately to a nearby berth on the Moscow River, the same one where earlier orbiters were loaded onto a barge for transportation to Zhukovskiy. It will either be turned into scrap metal or sold to a museum if anyone displays interest [53].

The airframes for vehicles 4K and 5K (nrs. 2.02 and 2.03) never reached com­pletion. Construction work was presumably halted after the Defense Council’s May 1989 decision to reduce the orbiter fleet from five to three vehicles. One report

suggests there were plans to turn one of the airframes into an underwater training mock-up for the neutral buoyancy facility at Star City, but that never happened [54]. Some elements of these airframes still lie in storage at the Tushino Machine Building Factory, but most parts have been turned to scrap.

With state orders for RD-170 and RD-171 engines running out, NPO Energomash began looking at international marketing opportunities for its engines in the early 1990s, setting its sights on America in particular. Realizing that the RD-170/171 thrust levels were beyond what was needed on American launch vehicles, the com­pany designed a two-chamber version of the engine called RD-180 that was tailored to the US market and was probably similar to a first-stage engine studied for the 11K55. In October 1992 Pratt & Whitney started working with Energomash to draw American customers to the RD-180 and a tripropellant engine known as the RD-701, and also to advise the Russian company on ways to implement a cost-accounting system [71]. The RD-180 was considered for use on a new two-stage Martin Marietta booster as well as an upgraded version of General Dynamics’ Atlas-II rocket [72].

In 1994 General Dynamics Space Systems was sold to Martin Marietta, which in turn merged with Lockheed in 1995 to become Lockheed Martin. The company continued looking at new engines to power its new Atlas-IIAR rocket (later renamed Atlas III) as well as a new generation of Atlas vehicles (Atlas V) being developed under the Air Porce’s Evolved Expendable Launch Vehicle (EELV) competition. In January 1996 Lockheed Martin’s choice fell on the RD-180, which beat the Aerojet – sponsored NK-33, a Russian engine originally developed for the N-1 Moon rocket,

and a derivative of Rocketdyne’s venerable MA-5A called the MA-5D. Just one nozzle of the RD-180 generates as much thrust as all three MA-5A nozzles combined on the older Atlas configuration.

The RD-180 essentially is an RD-170 “cut in half” with a new, less powerful turbopump driven by a single gas generator. About 75 percent of parts are identical to those of the RD-170. It has a sea-level thrust of 390 tons and a specific impulse of 311 s. The engine has several features that made it attractive to Lockheed Martin. It operates at much higher pressures than most other expendable booster engines, allowing the deep throttling capacity critical to effective engine use. The RD-180 can throttle over a 40-100 percent range, yet it remains flat in specific impulse throughout this range (losing just about a second of Isp), which is very important to fly the engine on both light and heavy-lift launch vehicles. The RD-180’s single-shaft turbine, liquid-oxygen pump, and single-stage propellant pump are all on one shaft, which cuts overall parts count, reduces cost, and translates to excellent reliability. Further­more, adoption of Russian seal and flange technologies virtually eliminated cryogenic system leaks that were accepted as normal on US boosters.

In early 1997 Energomash and Pratt & Whitney expanded their cooperation on the RD-180 into a joint venture called RD Amross LCC to build and market the engine. At the time the RD-180 accounted for 75 percent of Energomash’s business. In June 1997 Lockheed Martin announced it would purchase 101 RD-180 engines from Amross under a contract expected to be worth 1 billion dollars. In a move to allay concerns about relying on Russian technology for placing military and intelli­gence satellites into orbit, Lockheed Martin vowed that the US would set up its own production line at a new Pratt & Whitney facility in West Palm Beach, Florida, but those plans have run into numerous delays.

A prototype version of the RD-180 underwent an initial test firing at Energo­mash’s test facilities in Khimki in November 1996. The first test firing of a full-fledged engine followed in April 1997. Also applicable to the RD-180 were test firings of the RD-173, which had several new features that were incorporated into the RD-180. An RD-180 mated to an Atlas III thrust structure and tank simulator was first test-fired at the Marshall Space Flight Center in Huntsville, Alabama in July 1998. The Atlas III debuted in a spectacular launch from Cape Canaveral on 24 May 2000, success­fully placing into orbit a Eutelsat communications satellite. It was a landmark event in US-Russian space cooperation, very illustrative of the new, post Cold War atmo­sphere. A US rocket that had evolved from an ICBM conceived to level Soviet cities was now powered by a Russian rocket engine that itself had its origins in a program once seen as a crucial part of the military space race.

The Atlas III was retired in 2005 after seven successful missions, clearing the way for the new Atlas V generation. In November 1997 the Air Force had decided to modify its procurement plans for the EELV program, splitting the work between a pair of finalists rather than going for a single winner-take-all award. One of the major reasons given for the redirection was to enhance US space launch competitiveness by keeping two rocket builders in business. The work would now be divided between Lockheed Martin with its Atlas V family and McDonnell Douglas (later Boeing) with its Delta-4 family.

The Atlas V family uses a Common Core Booster (CCB) first stage fitted with an RD-180 engine and flanked by up to five solid rocket boosters. The Centaur second stage is powered by either a single or two RLA-10A-4-2 engines and the payload is protected by either a 4 or 5 m diameter payload fairing. There were also plans for an

Atlas V Heavy featuring three CCBs coupled together, but Lockheed Martin is no longer actively pursuing development of this version.

Given the slightly different flight modes for the medium-lift and heavy-lift Atlas V versions, the RD-180 had to undergo separate certification programs for the two versions, although it is exactly the same engine as flown on the Atlas III. The impressive RD-180 test-firing program was completed in early 2002. Since the first test in 1996, the RD-180 averaged a full flight duration firing every 10 days, encom­passing 135 total development and certification tests in Khimki, comprised of 91 Atlas III class tests, 30 Atlas V Medium class tests, and 14 Atlas V Heavy class tests. All totaled, the RD-180 racked up an impressive 25,449 seconds of development and certification test firing in Khimki alone, equivalent to 110 nominal Atlas V missions. The inaugural flight of the Atlas V took place on 21 August 2002. The RD-180 may also fly on the first stage of a Japanese rocket called Galaxy Express, which is expected to use the first stage of the Atlas III [73].

The requirements stipulated for the new piloted spacecraft in the Federal Space Program were so obviously tailored to RKK Energiya’s Kliper that many wondered if the tender was no more than a formality. However, in January 2006 the Russian Space Agency decided to extend the tender, asking the three companies to bring their proposals in closer agreement with the tender specifications. Finally, in a rather embarrassing move, the agency’s head Anatoliy Perminov announced at the Farnborough air show in England in July 2006 that the tender had been canceled without a winner. Instead, Russia would join forces with ESA to build an Advanced Crew Transportation System (ACTS), with RKK Energiya serving as the prime contractor on the Russian side. This is expected to become a much upgraded version of Soyuz incorporating European technology. An earlier invitation to ESA to join the development of Kliper had been turned down at an ESA ministerial meeting in December 2005.

Despite cancellation of the tender, RKK Energiya is continuing work on Kliper using its own resources. It has the full backing of Nikolay Sevastyanov, who suc­ceeded Yuriy Semyonov as head of RKK Energiya in May 2005. Sevastyanov holds out hope Kliper will eventually receive government funding and be ready to fly in 2015. However, there are signs of growing rifts between RKK Energiya and the Russian Space Agency, which considers Energiya’s plans overly ambitious and way beyond affordable limits. Only time will tell if the differences can be resolved and if Kliper will become the country’s first new piloted space transportation system since Buran.

Although there was significant spaceplane research in the Soviet Union in the 1960s, it was still dwarfed by the effort the country put into its mainstream manned space program, the one that was visible to the outside world. In terms of successes, there were two distinct periods in the Soviet piloted space program in the 1960s. The first part of the decade was marked by amazing triumphs that stunned the whole world. There was the pioneering flight of Yuriy Gagarin in 1961, the first flight into space by a woman (Vostok-6 in 1963), the first three-man flight (Voskhod in 1964), and the first spacewalk (Voskhod-2 in 1965). Then things started going downhill in spec­tacular fashion. First, there was the death in January 1966 of chief designer Sergey Korolyov, the mastermind behind the Soviet Union’s early space triumphs. After a two-year gap in piloted space missions, the maiden manned flight of the Soyuz capsule ended in disaster with the death of cosmonaut Vladimir Komarov in April 1967.

Meanwhile, in August 1964 the Soviet Union had secretly decided to send men to the Moon in response to the Apollo program, kicked off three years earlier by President Kennedy’s announcement in May 1961. The Soviet piloted Moon program was to be carried out in two stages, beginning with manned circumlunar flights (using the L-1 capsules and the Proton rocket) and culminating in manned landings on the lunar surface (using the L-3 complex and the massive N-1 rocket). While the Russians came relatively close to beating America in the circumlunar race, they never stood a chance of upstaging the United States in putting a man on the Moon. Already months behind schedule, the L-3 lunar-landing program was thrown into complete disarray by the catastrophic failure of the first two test flights of the N-1 rocket in February and July 1969.

At the same time, the Soyuz program continued as an independent effort, with a couple of missions flown in 1968 and 1969 (albeit with mixed success). While Soyuz shared many features with the manned lunar craft, the Soyuz program, essentially a

remnant of a canceled circumlunar project of the early 1960s, lacked a clear sense of direction.

Realizing that the ailing Soviet manned space program needed a fresh impetus, a small group of engineers within the Korolyov design bureau started working out plans in mid-1969 for an Earth-orbiting space station (Long-term Orbital Station or DOS) that could be built relatively quickly using available technology and would use Soyuz as a ferry vehicle. By early 1970 they saw their plans approved with the release of a key government decree that would determine the course of the Soviet Union’s piloted space activities for the remainder of the century. After a herculean effort lasting just over one year, the space station, officially dubbed Salyut, rocketed into orbit in April 1971. Unfortunately, the three cosmonauts who boarded the station two months later died during the return to Earth.

Eventually, Sadovskiy’s Department 16, then numbering fewer than 80 people, got down to working out a compromise plan that would satisfy all players. After several weeks of work, they came up with a Space Shuttle type configuration with a side – strapped winged orbiter (OK-92), but with the engines mounted on the “external tank’’ rather than on the orbiter itself. This turned the external tank and the strap-on boosters into a universal launch vehicle capable of flying not only the orbiter, but other payloads as well. Moreover, the number of strap-ons could be varied to match the required payload. On the one hand, the plan made it possible to build an orbiter very similar to the American one (and thereby benefit from American R&D) and, on the other hand, it allowed Glushko to retain his beloved family of launch vehicles.

The report prepared by Sadovskiy’s team was called “Reusable Space System With The Orbital Ship OK-92’’ and contained a comparative analysis with the OS – 120 and MTKVP. Before being sent to Ustinov, it needed to be endorsed by Glushko. Even though the new design went a long way to accommodate his wishes, Glushko realized his signature would probably be the death warrant for his lunar program. Finally, Burdakov was able to talk him around, arguing among other things that Glushko would still go down in history as the man having built the most powerful rocket engine in the world. On 9 January 1976 Glushko signed the report, albeit with mixed feelings. He even called it the “Bloody Sunday” of Soviet cosmonautics, referring to an incident where unarmed, peaceful demonstrators marching to present a petition to Tsar Nicholas II were gunned down by Imperial guards in St. Petersburg on 9 January 1905, exactly 71 years earlier [56].

Perhaps another reason Glushko came around was that the new plan enabled him to deal one final deadly blow to the N-1. Even though work on the N-1 had been suspended in 1974, the project had not yet been officially terminated. Boris Doro – feyev, the chief designer of the N-1, had even prepared an address to the 25th Congress of the Soviet Communist Party (to be held in February 1976) calling for the N-1 program to be resurrected. With the most likely payload for the N-1 now being a shuttle-type vehicle, the very same arguments against mounting a winged orbiter on top of the RLA could now be used against the N-1 as well [57]. Later the Russians would justifiably describe the absence of main engines on the orbiter as one of their system’s main advantages, although they rarely or never pointed out that this design had not been a foregone conclusion from the beginning.

Buran’s hydraulic system provided hydraulic pressure for positioning actuators needed to move the aerodynamic surfaces (elevons, body flap, rudder/speed brake), deploy the landing gear, operate the main landing gear brakes, and conduct nose wheel steering. Three independent hydraulic circuits were available to provide the necessary redundancy, with one being enough to safely land Buran. A four-circuit system was considered (as it was for the Space Shuttle Orbiter), but rejected due to weight considerations. Each circuit had a hydraulic pump and reservoir, containing

a hydraulic fluid. The hydraulic system was designed to operate in temperatures ranging from —60°C to +175°C. In order to keep the system warm enough in orbit, the hydraulic fluid was circulated periodically by an electric-motor-driven circulation pump to absorb heat from heat exchangers in each hydraulic circuit. To prevent the system from overheating during re-entry, each circuit was equipped with a water spray boiler.

Whereas airplanes use their engines to power the hydraulic pumps, gliders such as the Shuttle and Buran need Auxiliary Power Units (APUs) to perform the same function. Just like the Shuttle, Buran had three Auxiliary Power Units (Russian acronym VSU) in the aft fuselage. The VSUs were developed and built by NPO Molniya. They were fueled by hydrazine, which was decomposed in a gas turbine to produce a hot gas that powered a turbine that in turn ran a hydraulic pump. Engineers looked at several fuel combinations (tsiklin + an oxide, ammonia + nitrous oxide, hydrogen peroxide + hydrazine), but in the end settled for a hydrazine mono­propellant system, as on the Orbiter. The Russians probably made this decision before NASA realized that hydrazine-fueled APUs were not the best of choices. Aside from being a toxic fluid that requires special handling provisions, hydrazine is also a highly flammable chemical. This became all too apparent on the STS-9 mission in 1983, when a hydrazine leak caused a potentially catastrophic fire in Columbia’s aft fuselage only minutes before landing. The replacement of a hydra­zine-fueled APU by an electric APU was high on NASA’s priority list of Shuttle upgrades before the 2003 Columbia accident.

Having a dry mass of 235 kg, each VSU consisted of a fuel unit, the power unit itself, and a system controller. The fuel unit and power unit were built as one integrated system, two located on the left inner wall of the aft fuselage and one on the right inner wall. The system controllers were installed in an equipment bay at the base of the aft fuselage.

The fuel unit contained a single tank with 180 kg of hydrazine and several gaseous nitrogen tanks. Nitrogen was stored in these tanks at a pressure of 32 megapascals (MPa) and first passed through a pressure regulator where the pressure was reduced to 3.5 MPa before it entered the fuel tank to push the hydrazine to the power unit. Each fuel unit was hermetically sealed to prevent any hydrazine leakage into the aft fuselage of Buran. To minimize the fire hazard, the enclosure was purged with nitrogen during re-entry beginning at an altitude of 30 km.

The main elements of the power unit itself were the gas generator, the turbine, and an oil tank. In the gas generator the hydrazine passed over a catalyst bed, which decomposed it into a hot gas that drove a single-stage turbine. While the gas was vented overboard via an exhaust duct, a double-reduction gear reduced the turbine speed from 55,000 rpm to 4,500 rpm before the mechanical drive was imparted to the hydraulic pump. Oil was circulated through the system to lubricate and cool the gear-box and the turbine bearings.

The main difference between the Shuttle’s APUs and Buran’s VSUs is that the latter used a pressure-fed system rather than a pump to deliver the hydrazine to the gas generator. While the pressure-fed system consumes a slightly larger amount of fuel, it is less prone to fires and other serious malfunctions. Also, in the Shuttle the

fuel tanks are in different locations than the power units, complicating the plumbing and increasing the fire hazard.

The VSUs were designed to operate continuously for a maximum of 75 minutes. Because of the absence of main engines on Buran, the VSUs were not needed for gimbaling the main engine nozzles as was the case for the Shuttle’s APUs. However, the VSUs were still started shortly before launch to enable the vehicle to make an emergency landing in certain abort scenarios. They were shut down about 200 seconds into the launch because at that point Buran had enough energy to reach orbit if one or more core stage engines failed. After an in-orbit check-out the VSUs were not reactivated until after the deorbit burn at an altitude of about 100 km. On Shuttle missions one of the three APUs is activated before the deorbit burn, with the other two following afterwards [12].

For long-duration flights or flights requiring extra propellant reserves, it was possible to mount additional tanks in the payload bay. There was room for an additional fuel tank in the front of the bay and for an additional oxidizer tank (big or small) in the aft. These would have been placed such that the vehicle’s center of gravity was not disturbed. The additional tanks could have increased Buran’s overall propellant load from 7.5 tons to 14 tons, allowing the vehicle to reach an altitude of up to 1,000 km. Plans for a comparable “OMS kit’’ in the Shuttle Orbiter’s payload bay were never implemented.

In order to counter evaporation of the cryogenic oxidizer, Buran’s ODU was filled with supercooled LOX at a temperature of —210°C (with LOX having a boiling point of approximately — 180°C). This, along with the use of several layers of thermal insulation and LOX-mixing techniques, was enough to prevent any significant boil-off for 15 to 20 days. On longer missions the LOX would have been maintained at proper temperatures by circulating cooled helium through the tank’s heat exchanger and also by installing a special cryocooler using the so-called reversed Stirling cycle.

The ODU had an elaborate fault detection and identification system, consisting among other things of about 100 sensors to measure pressures, temperatures, vibra­tions, etc. The engines could be shut down in a fraction of a second if a dangerous situation developed [21].

If one of the core stage engines failed after T + 3m10s, Buran could still reach orbit, but the exact scenario depended on when the failure occurred and how much propellant Buran’s DOM engines needed to achieve that orbit, something that was calculated by the on-board computers. If the failure happened late in the launch, Buran’s DOM engines could have boosted the vehicle to its nominal orbit or to a lower but still usable orbit (in NASA parlance the latter scenario is called “Abort to Orbit’’, performed once by Challenger on STS-51F in July 1985). If it occurred much earlier, the remaining propellant in the core stage would have been burned to depletion, with Buran then firing its DOM engines to reach a very low orbit and somewhat later re-igniting those engines to initiate re-entry. Excess DOM propellant would have been expended prior to entry interface to meet center-of-gravity require­ments. This “Single-Orbit Trajectory” (OT) abort is the same as an Abort Once Around (AOA) on Shuttle launches [31].