Previous chapter: PTK NP development during 2011

Continuing their work on the next-generation manned spacecraft, PTK NP (a.k.a. PPTS), Russian engineers steered the project toward emerging new destinations in space and adapted the future ship to the changing fleet of future rockets. As partners in the International Space Station program eyed a return to the Moon and missions to the Lagrange points, developers of the PTK NP vehicle focused on these deep-space destinations.

Development status

RKK Energia, Russia's leading contractor in the PTK NP project, entered 2012 under a cloud of skepticism toward manned space flight expressed at the very top of the Russian space agency, Roskosmos. The new head of Roskosmos Vladimir Popovkin, soon after his appointment to the position less than a year earlier, publicly questioned whether the share of manned programs in the agency's portfolio had been disproportionately large. At the very same time, industry sources said that Roskosmos' main certification and research center, TsNIIMash, remained unconvinced of the need to replace the existing Soyuz transport ship with a new-generation vehicle.

Concurrently with domestic uncertainties, Roskosmos faced lengthy discussions on the international stage about possible directions of manned space flight after the completion of the ISS program, then expected sometimes after 2020. Some optimistic scenarios under discussion among the partners apparently included missions to the Moon and to the so-called Lagrange points, however a joint commitment to any ambitious enterprise in space remained to be penned.

Consolidating and refining the design

Anticipating the latest direction of the Russian space policy and possible budget restrictions, RKK Energia quietly dropped its plans to develop several variants of PTK NP ships that would be available to perform a variety of missions, such as servicing the space station, autonomous flights in the Earth orbit or reaching into deep-space. On April 12, Roskosmos issued a formal request to RKK Energia to focus the project on the development of the lunar vehicle.

As a result , a single spacecraft with the primary goal of carrying a four-member crew to lunar orbit has emerged as the focus of the PTK NP project during 2012. RKK Energia analyzed various orbits around the Moon and concluded that it would consider the polar orbit as the primary destination for the future vehicle. Despite a highest propulsion expense for reaching the polar orbit, it also provided almost unlimited access to any point on the lunar surface. (632) The same ship would also be capable of reaching Lagrange points, Russian officials said in July.

Typically for any complex machine in the process of development, the PTK NP spacecraft was slowly "gaining weight," as engineers were refining its various components and functions. Even the most basic mass characteristics of the PTK vehicle were yet to be finalized, according to industry sources. The crucial mass parameter of the descent module was reportedly fluctuating between 8.5, 9.5 and 10.5 tons as late as the beginning of the year. Despite an apparent effort to "diet" the ship to 9.1 tons, designers had to eventually compromise at 9.5 tons in 2012. As a result, a fully fueled Moon-bound spacecraft would have a mass of 23,641 kilograms - a huge increase from 16.4 tons projected for such a vehicle in 2008. For missions limited to the low Earth orbit, the spacecraft would be launched only partially fueled, thus reducing its mass to 17 tons.

Another round of recalculations completed by November brought a two-section vehicle to 20.3 tons, including a nine-ton crew module. A mass of the crew module was reduced from a maximum of 10,435 kilograms and a mass of the propulsion module from 13,206 kilograms.

At the end of the same month, the flight and testing department at RKK Energia finalized key documents on PTK NP, including blueprints of its exterior and interior, as well as on the tasks and key specifications of the spacecraft. (618)

Multi-launch lunar missions

This mass increase meant that a super-heavy rocket with a payload capacity of 120-130 tons would be needed to insert the lunar transport into an initial Earth orbit along with a special rocket booster, known as the Earth departure stage, as original plans had envisioned. However even the most optimistic funding prognosis for the Russian space program during this decade would not afford a heavy launcher with a payload exceeding 60-70 tons, Russian space officials said. As a result, engineers had to resort to a multi-launch scenario, which would include launching the 23-ton PTK NP into the Earth orbit, followed by the separate delivery of a rocket stage for escaping the Earth orbit. Independent observers estimated the mass of the Earth departure stage at 60-65 tons, which meant it would need a heavy booster to launch it. The two vehicles would have to dock before the Earth departure stage would send the spacecraft toward the Moon.

After a cruising flight between the Earth and the Moon lasting between three and five days, the Earth departure stage would also be used to slow down the vehicle and insert it into the lunar orbit roughly coinciding with the orbit of the Lunar Orbital Station, LOS. The Earth departure stage would then be discarded and the PTK spacecraft would use its own engines to rendezvous and link up with the orbiting facility. The PTK ship would also use its own propulsion to depart the lunar orbit on its way back to Earth.

As of 2012, PTK NP's propulsion section was to be equipped with a pair of engines reaching a thrust of 2 tons each. The ship's propulsion module would be carrying enough propellant to deliver a total velocity increase, or Delta V, of around 1,300 meters per second. This amount would afford up two dockings in the 100-kilometer orbit around the Moon and a trajectory correction maneuver during a back trip between the Moon and the Earth, which would not last more than five days.

Two or even three additional rockets would be required to deliver a lunar lander into the orbit around the Moon. In all, four or five launches would be spent to mount a single lunar expedition - clearly an impractical flight scenario for any long-term exploration of the Moon. The problem could be hardly resolved by sending long-duration crew to the lunar orbiting station, which would conduct multiple sorties to the lunar surface onboard either an expendable or a reusable lander. Without a super-heavy launcher in the immediate future, Russia would probably have to rely on a US-built rocket, if an international agreement could be reached for a joint lunar exploration.

Re-designing for new rockets

The 2011 decision of the Russian space agency, Roskosmos, to discontinue the development of the Rus-M rocket left the PTK NP project without a launcher.

RKK Energia's forward-looking plans relied heavily on Rus-M and its more powerful derivatives to launch the PTK NP spacecraft and other manned vehicles, such as lunar landers. Following the premature death of the Rus-M project, the company considered various alternatives, such as launching on the existing Zenit rocket, upgrading either Zenit or Soyuz rockets or switching to the yet-to-be-completed Angara family. By the beginning of 2012, a total of five candidate launchers were considered:

Three different adapters had been drafted for the integration of the spacecraft with each of these rocket families. RKK Energia was closely involved into the production of the Zenit rocket under the Sea Launch venture and had recently made a number of steps to ensure the survival of the financially vulnerable project. However w ith the ever increasing mass of the spacecraft, the smaller Zenit and Angara-3 rockets had to be ruled out. During the first half of 2012, Angara-5 was emerging as a favorite from the engineering standpoint, but this option was hampered by the need to build a new launch pad in Vostochny or in Baikonur.

During 2011, some studies also looked at launching unmanned test versions of PTK from a soon-to-be-completed Angara pad at Russia's northern cosmodrome in Plesetsk. By October of that year, engineers also completed the calculation of four different trajectories that could be followed by the Angara-5.2 rocket carrying PTK NP from Vostochny. (575)

In the meantime, during the summer, Roskosmos announced a formal tender for the development of the new "lunar" version of the launch vehicle for the manned space program, which would be based at Russia's future launch site in Vostochny, in the nation's Far East. Specifications for the future vehicle closely matched those of the Angara-5 rocket, even though it had never been mentioned in the tender documentation. Not surprisingly, GKNPTs Khrunichev, the Angara developer, turned out to be the only bidder in the "tender" and the company was ultimately awarded the contract.

Sodruzhevstvo-based designs

In another potentially significant development on the launch vehicle front, RKK Energia apparently attempted to revive the idea of the Sodruzhestvo heavy-lifting rocket that could be developed jointly by Russia and Ukraine and based in Baikonur. With a payload capability of 64 tons, the rocket could deliver the PTK NP spacecraft attached to an additional space tug, which apparently derived from Block D upper stage and had a designation SMT-2, where SMT stood for a Russian abbreviation of Means of Inter-orbital Transportation. In the meantime, a larger SMT-1 stage equipped with four engines apparently derived from the RD-124 propulsion system and developing around 30 tons of thrust. Estimates showed that both SMT-1 and SMT-2 stages burning kerosene fuel would have to be used to send the PTK NP spacecraft from the low Earth orbit to the Moon. SMT-2 would fire again to insert the spacecraft into the lunar orbit. Naturally, engineers continued looking into the possibility of developing a more efficient upper stage burning liquid hydrogen fuel.

Flight test program

During 2012, RKK Energia reached the final stage of work on the second phase of the PTK NP development known as the Technical Project, with most of the work conducted largely in secret. Public updates on the development status were mostly limited to statements by the chief of RKK Energia Vitaly Lopota and by top officials at Roskosmos. In May, Lopota promised the ship to be ready for flight testing in 2015. A month later he told the Interfax news agency that the development of a heatshield and some other hardware for the vehicle had already been completed, while the overall Technical Project had been ongoing. The heatshield developed for the spacecraft would be qualified for returning to Earth with a higher reentry speed associated with deep-space missions. As one of the most critical new systems in the PTK NP project, the heatshield came to the forefront of the emerging flight test program.

The initial goal of unmanned flights would be testing the more capable thermal protection system that would enable the vehicle to survive reentry after the return from the Moon with a speed of around 11 kilometers per second, comparing to around seven kilometers per second experienced during the Earth-orbiting missions. From vague statements by the Roskosmos chief, it sounded that at least initial versions of the spacecraft would be expendable, rather than reusable as the original project had previously implied. (576)

Typically for manned spacecraft development, its test flight program would start with drop tests of the crew module from an aircraft, followed by an orbital launch of the crew reentry vehicle on the Zenit, Soyuz or Angara. Due to the very high cost of the full-scale test model, engineers reportedly considered equipping the unmanned vehicle with an emergency escape system. In case of launch failure, the costly test article would be saved, however had the launch succeed, a nominal procedure for discarding the escape system during future manned missions would be tested. (577)

In the course of the PTK project, RKK Energia reportedly made its own investments into future test infrastructure. The installation of a new autoclave was completed at the company's campus in Korolev and the construction of a new facility for acoustic tests was in final stages.

Back to Baikonur

A chorus of Roskosmos officials beginning with the agency head left no doubt that unmanned missions in the PTK NP program would be "temporarily" originating from the Baikonur cosmodrome and be carried aloft by the Zenit or even the Proton rocket. Another Russian official ruled out the purported reliance on the Soyuz rocket for the project. (578)

Baikonur could also be the home for the heavy-lifting Sodruzhestvo rocket, if Russia, Ukraine and Kazakhstan would agree to develop the project.

As late as May, Russian space officials continued talking about the possibility of starting test flights in 2015. The first manned mission was promised as early as 2018. In reality, both of these dates (probably designed to match NASA's timeline for the development of its Orion spacecraft) had long became utterly unrealistic. In July, the head of the Russian space agency, Vladimir Popovkin, discussed the 2017-2018 timeframe only in context of starting unmanned test launches. (576)

As of the end of 2012, three unmanned launches of the PTK NP spacecraft from Baikonur had been planned. After that, manned launches would follow from Vostochny. With the introduction of the heavy-lifting launch vehicle capable of sending PTK NP toward the Moon, two more unmanned launches would be required.

Emergency escape profile

During the first 56 seconds of the flight, the emergency return of the vehicle would be conducted back to the launch site. Further emergency escape scenarios would cover 729 seconds out of a 748-second launch sequence. This escape scenario was validated by firing tests of solid rocket motors at the Moscow Teplotekhnics Institute, MIT, the developer of Russia's solid-propellant ballistic missiles, including the latest Topol-M and Bulava ICBMs.

Despite initial reliance for the launch site in Baikonur, during the Technical Project, engineers had no choice but to consider much more complicated orbital trajectory originating from Vostochny. To cut the length of the trajectory over the vast Pacific Ocean, which would have to be reachable by rescue services in case of emergency, the spacecraft would use its own engine to complete the orbital insertion. Still, three vessels and four aircraft spread below flight path of the launch vehicle would be required in order to reach the crew within four hours after the emergency splashdown. The aircraft involved in the emergency recovery operations over the Pacific would carry a special cater, which would be dropped under a parachute at the emergency landing site. Cosmonauts could then remain onboard the vessel up to two days before the rendezvous with a rescue ship. (632)

Landing sites

The lunar polar orbit missions presented additional challenges for landing of the spacecraft. Orbital mechanics limited the return to the regular landing area to just two days every two weeks, greatly increasing the risk to the mission in case of the need for an emergency flight home. In addition, the analysis of satellite imagery ruled out some of the landing sites on the Russian territory, which were selected by the cartographic review during the preliminary design. The landing accuracy of the crew module was given at five kilometers. (632)

As a result, engineers selected backup sites, apparently including those on the Kazakh territory. Although Earth-orbiting missions of the PTK NP spacecraft could touch down as close as 87 kilometers south of the yet-to-be built Vostochny Cosmodrome, the primary landing areas for lunar flights had to be either in a 100 by 140-kilometer ellipse in Kazakhstan or in a 50 by 50-kilometer area in the Russian republic of Kalmykia, northwest of the Caspian Sea.

A total of five landing sites were selected, which could be reached following the track of the descent module across the Antarctic, the initial entry into the atmosphere, a "skip" maneuver taking the capsule above the atmosphere and, only then, the final reentry and the touchdown.

Completion of design

At the end of December, the leadership of RKK Energia reported that the company had completed the design of the PTK spacecraft and had planned to start manufacturing prototypes and flight hardware for the next-generation spacecraft in the following year. (617) RKK Energia apparently finished the work despite an addendum to the formal technical assignment issued by Roskosmos on April 12 and giving the company until June 2013 to address all the requirements.

By the end of the design process, the project documentation included 1,073 volumes, including 407 volumes generated at RKK Energia and 666 volumes issued by various sub-contractors. A total of 17 scale models of the crew module and the payload section had been manufactured and tested at wind tunnels in 250 different tests. A total of 40 technical reports covered the results of various experiments. Plasma generators were used to test thermal properties of the crew module and its protective materials during the reentry into the Earth atmosphere from lunar trajectories. (632)

Workable prototypes manufactured during the Technical Project included main flight computer modules, flight control displays, fiber-optic gyroscope, telemetry avionics components, parachute system, power supply and management system, cosmonaut chairs and other hardware. (634)

Next chapter: PTK NP development in 2013

APPENDIX

The lunar version of the PTK NP spacecraft as of mid-2012:

Mass of the crew module, VA 9,500 kilograms Dry (unfueled) mass of the propulsion module, DO 4,500 kilograms PTK NP launch mass on the ground (VA and DO) approximately 17,000 kilograms PTK NP full mass in the low Earth orbit before the escape maneuver toward the Moon approximately 23,000 kilograms A total Delta V capacity of the dual propulsion system in the DO propulsion module approximately 1,300 meters per second

Mass characteristics of the PTK NP spacecraft as of end of 2012:

Liftoff mass of PTK-NP (lunar version) 21,367 kilograms Mass of PTK after separation from SMT stage (in a lunar orbit) 20,000 kilograms Mass of PTK after docking with the lunar vehicle, VM 19,700 kilograms Mass of PTK after undocking from the lunar vehicle, VM 19,400 kilograms Mass of PTK prior to separation of the command and service modules (before atmospheric reentry) 12,900 kilograms Mass of the descent module, VA 9,000 kilograms Launch mass of PTK on a mission to the Earth-orbiting space station 14,400 kilograms Mass of PTK after the separation from the Earth-orbiting space station 13,600 kilograms Mass of PTK prior to separation of the descent module, VA, and the propulsion module, DO 12,800 kilograms

Writing, animation, interactive graphics and illustrations by Anatoly Zak

Research and technical estimates by Igor Rozenberg and Vladimir Shtanin; Last update: August 18, 2013

Page editor: Alain Chabot; Last edit: September 22, 2012