PTK NP will consist of the re-entry vehicle and engine compartment. The manned re-entry vehicle is cone-shaped and comprised of the crew capsule and soft landing powerplant. The crew capsule houses four Cheget seats for the cosmonauts. Unlike the in-service Kazbek seats in the Soyuz spacecraft, the Cheget seats have no individual seat liners, are more comfortable and allow quick adjustment to accommodate a particular occupant. The rescue craft version of PTK NP fitted with two extra Kazbek seats will be able to bring six cosmonauts back down to the Earth. The crew capsule is reusable, can be used up to 10 times on near-earth orbit missions and three times beyond near-earth orbit.

The capsule houses the life support system and onboard control system with the cockpit management system (flight data are shown on three touch-screen multifunction liquid-crystal displays). The craft can be controlled from two workstations. During the development, close attention has been paid to ergonomics and technical aesthetics, workstation and manned compartment layouts, emergency procedures, flight equipment and requirements to the mission equipment.

The control stick features an original design, for it is the only one and has a special design. The specifications requirement provides for the one-pilot control feasibility but for the availability of two equal workstations. For this purpose, the designers developed a special multichannel integrated control stick, which closest analogue is the side-stick on some aircraft. The control stick allows control of both attitude and movement of the craft by means of relevant buttons. It sits between the seats and can be used by either of the two cosmonauts at the workstations.

Among other things, the development of PTK NP was aimed at a sharp reduction in the dispersion pattern during landing. For this purpose, the descent control system was to be improved (an increased lift-drag ratio of the re-entry vehicle at the hypersonic leg of the descent, a higher accuracy and a quicker action of the reaction control system) and parachute descent was to be abandoned or its duration was to be minimised as much as possible. To this end, the first preliminary design provided for a purely reaction landing system. The improved engineering design reduced the part to be played by the system by far, with the descent speed to be slowed down mostly by the parachutes that are to be deployed at as low an altitude as possible to increase the accuracy of the landing.

The reusability of the crew capsule is owing to reducing the g-load when hitting the ground during the landing by means of the landing system and soft-landing powerplant. The latter is controllable. It turns on just before the touchdown and slows the vertical and lateral velocity down, thus not only reducing the g-load but also preventing the capsule from overturning after touchdown. The landing system, comprised of solid-propellant soft-landing engines and four extendable shock-absorbing struts, is in the disposable compartment in the lower part of the lander.

The obvious advantage offered by the combined parachute/rocket-assisted system is a reduction in the craft's weight and internal volume. For instance, the overall weight of the 'purely rocket-assisted' landing system is 2,725 kg, while that of the parachute/rocket-assisted system equals a mere 1,800 kg. To cap to all, the rocket engines can reduce the vertical and lateral speed down to zero with one of the three main canopies failed and wind speed in the landing area being up to 15 m/s.

If the soft-landing engines fail, the crew's safety is ensured by the shock-absorbing seats capable of cushioning the shock overloading at an impact speed of up to 7 m/s. The emergency landing technique is roughly the same, but the struts do not extend and the impact energy is offset by the deformation of the lower part of the capsule, which becomes disposable in such a case.

The engine compartment is disposable and of cylindrical shape. It houses a liquid-propellant sustainer engine and a number of units and systems unnecessary during the landing. The compartment's hull mounts folding solar panels, cooling system's heat exchangers, radio communication and flight control antennas, an array of sensors and the attitude control system's microengines.

Until recently, the public has known little about the purpose and employment of PTK NP. While it was more or less clear about flights to low-Earth orbit, the Moon expedition raised questions that had simply lacked official answers before the MAKS 2015 air show.

At the show, a video clip was shown at Energia's stand about the developer's concept of the Russian lunar expedition. The endeavour, which can be broken down into four stages, will be implemented through launches of Angara-A5V enhanced-capacity heavyweight launch vehicles.

At Stage I, two LVs will blast off from Vostochny space centre to insert into low-Earth orbit the LVPK lunar lander/launch module without the crew but with the MOB2 interorbital oxygen/kerosene tug being derived from the upgraded DM upper stage used on the Proton and Zenit-3SLB LVs. This will be orbited by one of the two LVs. The other will loft into orbit the powerful MOB1 interorbital oxygen/hydrogen tug being derived from the heavyweight oxygen/hydrogen upper stage of the Angara launch vehicle. The spacecraft will dock and head for the Moon, powered by the MOB1. Once the Moon orbit has been reached and the MOB1 jettisoned, the LVPK lander/launch vehicle is brought to low-lunar orbit by the MOB2 orbital tug.

At Stage II, two more LVs carry into low-Earth orbit the PTK NP manned cargo spacecraft (the heavy lunar version with the crew on board) fitted with the MOB2 and another MOB1 interorbital oxygen/hydrogen tug. They converge, dock, accelerate towards the Moon and reach near-lunar orbit.

At Stage III, PTK NP and LVPK dock in lunar orbit, with part of the crew transferring to the LVPK. The lunar module leaves the orbit and conducts soft landing on the Moon. The cosmonauts disembark near one of the lunar poles where water ice was detected and conduct research.

The getting back from the Moon is much easier than getting there. LVPK takes off and docks with PTK NP in orbit, and the moonwalkers come to PTK NP that sets of for the Earth under its own power. Once in near-Earth orbit, the spacecraft's compartment separate, with the lander (crew capsule) entering the atmosphere and landing.

PTK NP has been designed since 2009. Initially, it was planned that the first unmanned spacecraft launch into low-Earth will take place in 2015 and the manned one in 2018. Interestingly, Energia wanted to use the Energia-K medium booster for orbital flights and the superheavyweight launch vehicle for the expedition to the Moon. It could be deduced from several presentations that the manufacturer planned the development of the LV independently or in cooperation with Progress Space Rocket Centre and Makeyev design bureau.

In mid-July 2014, the managers of Energia specified the status of the programme more accurately: in late 2013 the corporation and the Federal Space Agency signed a contract for the release of the detailed design documentation for all components of the spacecraft, including individual instruments and assemblies, the manufacture of relevant mock-ups, prototypes, etc. Under the contract until late 2015, Energia committed to conduct ground component tests of the hardware and test the basic PTK NP manufacturing processes.

The development of the detailed design documentation for the spacecraft continued in summer and autumn 2014, with technical specifications issued to associate contractors. Agreements were made with some of the subcontractors.

In March 2015, Yuri Koptev, chairman of the scientific and technical council of the Federal Space Agency, announced the development of the Angara-A5V launch vehicle for the multiple-launch Moon expedition with the use of PTK NP. According to the developer, Khrunichev, the advanced launch vehicle will be insert into low-Earth orbit half more weight than the 'standard' heavyweight Angara-A5, which flight tests kicked off at the Plesetsk space centre in December 2014.

The decision against developing a superheavyweight launch vehicle resulted to reduce the dry weight of PTK NP stringently through replacement of structural materials. Initially, the lander was to be welded from milled aluminium-alloy waffle panels, but now it has a three-layer structure with carbon-fibre composite skins and the aluminium honeycomb filler.

Energia and German company Nanotec GmbH co-developed a PTK NP hull manufacturing technology using carbon-fibre composites. Nanotec GmbH supplied Energia with a sealed hull prototype unveiled at MAKS 2015. Energia, the United Rocket and Space Corporation and the Roscosmos federal corporation are gong to set up production facility in Russia to introduce the technology to various domestically developed spacecraft.

The PTK NP programme's schedule has been modified heavily recently. The flight tests of the unmanned version of the spacecraft will start in 2019-21 at the earliest, the first manned flight in near-Earth orbit has been put off to 2024 and the first lunar expedition is slated for 2028.

Energia President Vladimir Solntsev said on 29 August 2015 that the company was going to speed up the construction of the flying example of the craft: "Although we announced the first launch to be conducted in 2021, we decided to make the first example as soon as 2019, and I think we will manage to do so."

The first draft 2016-25 Federal Space Exploration Programme included five PTK NP flights. The first phase of its flying trials implied launching an automatic low-orbit PTK NP version to the ISS on the Angara-A5 carrier vehicle. In all, three flights were planned for 2021, 2022 and 2023 - one a year. The crew was scheduled to go to the orbiter in 2024. Phase II, which will commence in 2025, will see the lunar variant of the spacecraft flight-tested.

Probably, the Angara-A5P two-stage launch vehicle will be used for low-Earth orbit insertions. It differs from the baseline Angara-A5 in lacking the third stage, which enables it to loft into orbit only 14.5-20 tons of cargo (depending on the operation of the second stage), rather than 24 tons. This is quite enough for both smooth launch of the 'light' - orbital - variant of PTK NP and low-Earth-orbit trials of the lunar ship.

:It has been several years since the development of the future manned spacecraft kicked off, but it still lacks a name. Therefore, Energia has recently announced a competition for the best name for PTK NP. The competition started on 30 August 2015 and will end on 2 November 2015. Its outcome will be announced in mid-January 2016, and public vote and the jury will determine a winner. The top prize will be a trip to Baikonur cosmodrome to attend the launch of a Soyuz manned cargo spacecraft.

Published in Take-off magazine, November 2015.

(Photo: Andrey Fomin)