This June 26, 2017 file photo shows Long March-5 Y2 carrier rocket at Wenchang Space Launch Center in south China's Hainan province.  (ZHANG WENJUN / XINHUA)

BEIJING — The maiden flight of the Long March-5B rocket carrying a trial version of China's new-generation manned spaceship is expected to take place in April, indicating the imminent start of construction of China' space station.

The rocket, the prototype core capsule of the space station and the experimental manned spaceship are undergoing tests at the Wenchang Space Launch Center on the coast of south China's island province of Hainan.

The Long March-5B is a modified version of the Long March-5, currently China's largest carrier rocket

During the flight in mid to late April, the experimental manned spaceship will be sent into space with no crew. The prototype of the core capsule of the space station will not be launched.

The Long March-5B is a modified version of the Long March-5, currently China's largest carrier rocket, and will be mainly used for sending capsules of China's space station and large spacecraft to the low-Earth orbit, according to the China Manned Space Agency (CMSA).

Space engineers developed a new large fairing, which is 20.5 meters long and 5.2 meters in diameter, for the Long March-5B. The whole rocket is about 53.7 meters long, with a 5-meter diameter core stage and four 3.35-meter diameter boosters.

 ALSO READ: Overview: China's major space programs in 2020

The rocket uses environment-friendly fuel, including kerosene, liquid hydrogen and liquid oxygen. It has a takeoff weight of about 849 tonnes and a payload capacity of 22 tonnes to low-Earth orbit, said Wang Jue, chief director of the Long March-5 development team at the China Academy of Launch Vehicle 

Technology under the China Aerospace Science and Technology Corporation.

After the maiden flight of the Long March-5B, the Long March-5 carrier rocket will launch China's first Mars probe and the Chang'e-5 lunar probe later this year.

China aims to complete construction of the space station around 2022. According to the CMSA, more than 10 missions are planned in the next three years to complete the construction and master technologies for in-orbit assembly and construction of large complex spacecraft, long-term manned spaceflight in near-Earth space and large-scale space science experiments.

READ MORE: China prepares to launch Long March-5 rocket

China still faces many challenges, so joint drills at the space launch center and the maiden flight of the Long March-5B are very important, said experts.