China’s new-generation space launchers, Chang Zheng-5 (CZ-5) and Chang Zheng-7 (CZ-7), will both make their debut flights in 2016. During his recent interview with the China News Service, Lei Fanpei, Chairman of the China Aerospace Science & Technology Corporation (CASC), revealed that CZ-7 will make its debut flight in June this year, followed by the CZ-5 in late September or early October. However, he did not disclose what payloads, if any, will fly on these missions.
Ready to Fly
After decades of incremental improvements to its existing launch capabilities, the Chinese space programme is currently undergoing a major technological overhaul. This will eventually see the construction of new spacecraft and rocket fabrication facilities in Tianjin and a new space launch centre on the southern island of Hainan, as well as the introduction of an entire family of more capable launch vehicles burning non-toxic, non-polluting liquid propellants. Once fully operational, these new elements will greatly increase China’s future space capabilities.
A ground testing vehicle of the CZ-7 launcher was delivered to the Hainan Space Launch Centre in late 2014 for an all-system launch simulation drill. Welding of the propellant tanks for the first flying CZ-7 commenced in April 2015, and the assembly of the launch vehicle designated CZ-7-Y1 is currently underway at the rocket fabrication facility in Tianjin. Initially the rocket will be used to launch the Tianzhou cargo vehicle. A certain number of unmanned missions will need to be achieved to fully verify the launcher’s design, before it can be adopted for manned missions.
The all-system launch simulation drill of the CZ-5 using a ground testing vehicle commenced at Hainan in September 2015 and is expected to complete in February 2016. Construction of the four strap-on boosters began at the Shanghai Academy of Spaceflight Technology (SAST) in November 2015, and the assembly of the flying CZ-5 vehicle at the Tianjin rocket fabrication facility is underway.
Question remains as whether the two missions will carry any payload. The Chinese aerospace industry has a tradition to carry fully operational payload on debut flights of its Chang Zheng series launchers, but neither of the two new launchers will have their intended payload ready for flight in 2016. The first Tianzhou vehicle is scheduled for launch sometime in late 2017 to perform an in-orbit resupply mission with the Tiangong 2 space laboratory module, due for launch in 2016. Similarly, the first confirmed payload for the CZ-5 launcher is the Chang’e 5 lunar sample return mission, currently scheduled for 2018. It is therefore possible that a mock-up of the intended payload will fly on these missions.
CZ-7
The CZ-7 is a medium-lift orbital launcher developed by China Academy of Launch Vehicle Technology (CALT). Development of the launcher commenced in 2010. Initially the rocket will be used to launch the Tianzhou cargo vehicle from Launch Complex 201 in the newly-built Hainan Space Launch Centre. A man-rated CZ-7 has been proposed and will be introduced after the unmanned variant has achieved a certain number of flights in order to fully validate its design and demonstrate its reliability and safety.
The basic variant CZ-7 is in a configuration of two-stage core vehicle with four strap-on liquid rocket boosters, powered by the newly developed YF-100 and YF-115 liquid rocket engines, both burning kerosene as fuel and liquid oxygen (LOX) as oxidiser. The entire launch vehicle stack is 53.1 m in length, with a total launch mass of 594 t and a launch thrust of 7,200 kN (734 t). The payload fairing is 4.2 m in diameter. The launcher will be capable of delivering 13,500 kg payload to a 200 x 400 km orbit inclined at 42°, or 5,500 kg payload to a 700 km sun-synchronous orbit (SSO).
CZ-5
The CZ-5 is China’s new generation heavy-lift space launcher, comparable in performance to the European Ariane 5 and the U.S. Delta IV Heavy. The launcher is designed to loft large commercial satellites, space station modules, and deep space probes. The CZ-5 programme gained governmental approval in June 2004, with the aim to introduce a heavy-load orbital launch vehicle capable of delivering 14 tonnes of payload to the geostationary transfer orbit (GTO), or 25 tonnes to the low Earth orbit (LEO). The primary contractor is CALT, with the participation of SAST to produce some components of the rocket.
The CZ-5 uses a 5 m diameter core stage powered by two LOX/LH2 YF-77 engines, each rated at 509.6 kN at sea-level. The four 3.35 m diameter strap-on boosters are each powered by two LOX/Kerosene YF-100 engines, each rated at 1,179 kN. The upper stage on the core vehicle is powered by two LOX/LH2 YF-75D engines. This configuration is used for GTO launch missions, with a maximum payload capacity of 14 t. The payload fairing is 5.2 m in diameter and 12.5 m in length. The CZ-5B variant without the upper stage will be used to launch modules of the space station Tiangong, with a LEO payload capacity of 25 t.
Space Infrastructure
So far, the Chinese space programme has been relying on the CZ-2/3/4 series of rocket launchers introduced in the 1970s—90s for its orbital launch missions. All of these launchers were essentially derived from a single rocket design — the liquid-fuel DF-5 (CSS-4) intercontinental ballistic missile (ICBM) that first flew in 1971. The first-stage of the rocket is powered by a cluster of four parallel YF-20 rocket motors (collectively known as YF-21), each producing 75 t (740 kN) of thrust at take-off. By adding four strap-on boosters and/or upper stages, the rocket can deliver up to 9.5 t payload to LEO or 5,500 kg to GTO.
The payload capability of the current generation of Chang Zheng space launchers has reached a ceiling due to a single factor of logistics: as China’s three existing launch sites are all far inland, launch vehicle components have to be transported from their factory to launch sites by railway. The size of the launcher is limited to 3.35 m in diameter and about 14 m in length. Any design bigger than these dimensions will not fit through the railway tunnels. In addition, a rocket with high length-to-diameter ratio also brings challenges to its flight control system.
To break this limitation, China has completely overhauled its space infrastructure, which involves the construction of a new rocket fabrication and testing facility in the eastern coastal city of Tianjin and a new coastal launch centre on the Hainan Island in southern China. Rocket boosters built in the Tianjin facility will be transported by specially designed cargo ships via a sea route to the launch centre. This approach not only eliminates the limitations in rocket size, but also brings additional benefits in downrange safety and launch dynamics due to the launch centre’s coastal location and its proximity to the Earth Equator (19° N).
