Mittwoch, 16. Dezember 2015 - 08:43 Uhr
As China continues to progress towards the construction of a manned space station in the LEO around 2020, the Chinese space industry is now working on the concept of a next-generation multipurpose crewed spacecraft vehicle, which can transport crew or cargo to the Moon, Lagrange Points, Near Earth Asteroids and Mars.
According to a research paper titled “Concept Definition of New-Generation Multi-Purpose Manned Spacecraft”, the future Chinese multi-purpose crew vehicle will be a capsule-type spacecraft, capable of carrying 2 to 6 crew members to Earth orbit and beyond. The spacecraft will be built in two versions: a 14-tonne version for LEO, Near Earth Asteroid and Mars missions, and a 20-tonne version for lunar landing missions. The two versions will be based on the same crew module design, but feature different propulsion systems to meet different mission requirements.
The paper was published published in the January 2014 issue (Vol.35) of Chinese Journal of Aeronautics by the Institution of Manned Spacecraft System Engineering (IMSSE), a R&D centre of China Academy of Space Technology (CAST) and the designer of the Shenzhou vehicle. The paper’s authors include a number of senior IMSSE staff such as Yang Lei (IMSSE chief engineer), Zhang Bainan (IMSSE director) and Huang Zhen (IMSSE vice director).
The paper envisages that China’s future human space flight programme will comprise five typical types of missions: ferry flights to and from the space station in the LEO, as well as exploration missions to Lagrange Points of the Earth-Lunar System, Lunar surface, Near Earth Asteroids, and Mars. The future Chinese crew vehicle will therefore need to be able to support all of these missions with a single baseline design, using a modular architecture to achieve high degrees of flexibility, expandability, and reusability.
For lunar landing and deep space missions, the spacecraft will need to carry up to 4 crew members. For ferry flights to the LEO space station, the spacecraft is required to carry up to 6 (the maximum number of crew members supported by the future Tiangong Space Station).
Based on the concepts of future lunar landing and deep space missions, the future multi-purpose crew vehicle is required to be capable of serving independently in orbit for at least 21 days, or 2 years if docked with the space station.
The future LEO and deep space flight missions will require a delta-v of 800 m/s, whereas the future lunar landing mission will require 1,700 m/s. This will be satisfied by the introduction of two different service modules for the spacecraft vehicle.
For deep space and lunar missions, the crew module will need to sustain a re-entry velocity of 11.2 km/s (second cosmic velocity).
The future Chinese multi-purpose crew vehicle will be launched aboard either the CZ-7 or CZ-5 rocket launcher, both expected to fly in 2016. The CZ-7 has a payload capacity of 14 t to the LEO, while the CZ-5 has a payload capacity of 25 t to the LEO. Both launchers are currently in development, and will require further modifications to become man-rated.
It can be seen that the design of the future Chinese crew vehicle bears some influences by the U.S. next-generation crewed spacecraft vehicles currently in development, such as the Boeing CST-100 and Orion CEV.
The two versions of the future Chinese multi-purpose crew vehicle
Aerodynamic design: The crew module will be in a blunt cone shape, similar to that of the Boeing CST-100 or Orion CEV.
Arrangement: Instead of the three-module arrangement of the current Shenzhou vehicle, the future Chinese crew vehicle will adopt a two-module arrangement, with a large inhabitable crew module at the front, and an uninhabitable cylindrical-shaped service module at back. The size of the re-entry vehicle will be twice of Shenzhou’s, capable of accommodating up to six crew members. A docking port and its associated docking sensors are fitted to the front-end of the crew module. The spacecraft can be fitted with two different service modules, with different propulsion systems and propellant capacities.
Emergency escape system: The future Chinese crew vehicle will feature an integrated launch escape system, with solid rocket launch abort motors fitted on the service module to separate the entire spacecraft vehicle from the rocket launcher in case of emergency.
Thermal shielding: The thermal shield of the future crew vehicle will be made from light weight ablator material, such as Phenolic Impregnated Carbon Ablator (PICA).
Recovery: The paper suggested that the future crew vehicle should be recovered using sea-landing at a location near the Earth equator off Chinese coast, while retaining the land recovery capability as backup. The re-entry capsule will be equipped with multiple parachutes and airbags for a soft landing at sea or in land.
Reusability: The paper suggested that the future crew vehicle should explore the possibility of a reusable crew module (or some of its systems) in order to lower the vehicle’s operational cost.
TT&C: The future Chinese crew vehicle will be capable of continuous communications throughout the atmospheric re-entry.
The paper outlined the key technologies required for the development of the future crew vehicle, including:
A system design approach allowing optimisation, modularisation, and reusability;
Aerodynamic design for high-velocity atmospheric re-entry, as well as its demonstration and validation;
Light weight ablator thermal shield;
Guidance, navigation and communications (GNC) during high-velocity atmospheric re-entry;
Spacecraft sea recovery using multiple parachutes;
Advanced launch abort system, including the miniaturised solid rocket motor;
Highly integrated avionics;
Spacecraft self-diagnosis system;
It is understood that the concept evaluation stage of the future multi-purpose crew vehicle began around 2013, and the development was initiated later in the same year. CAST is responsible for the development of the spacecraft’s crew module, while the service module may be developed by a different institution of the China Aerospace Science & Technology (CAST) consortium.
The first flight of the spacecraft vehicle can take place as early as 2020, but this will depend on the future mission requirements, the development progress of the CZ-5 and CZ-7 launchers, and the construction of new launch facilities at either Jiuquan or Hainan launch centre.
In November 2015, 508 Institute of CAST completed an airdrop test using a set of three parachutes, each with 1,200 square metres of surface area. The test was believed to be associated with the development of the future multi-purpose crew vehicle.
Once in service, the multi-purpose crew vehicle is expected to replace the Shenzhou spacecraft current in use for all future human space flight missions.