China's new generations of the Long March rocket family, Long March-5, -6 and -7 are expected to make their maiden flights in the next five years, a rocket scientist has said.

Yu Menglun, also academician of the Chinese Academy of Sciences, said in a recent interview that China has sought to develop non-toxic, low-cost, highly reliable, adaptable and safe carrier rockets in its research of the new generation products.

Long March-5 rocket will be using non-toxic and pollution-free propellant. It has a maximum low Earth-orbit payload capacity of 25 tonnes and geosynchronous orbit payload capacity of 14 tonnes.

The Long March-6, which is designed to be a high-speed response launch vehicle, has a minimum of 1 tonne of sun-synchronous orbit payload, according to the scientist.

The Long March-7 has a maximum low Earth-orbit payload capacity of 13.5 tonnes and 5.5 tonnes of sun-synchronous orbit payload, he said.

The Long March rockets currently fall into four categories, namely the Long March-1, Long March-2, Long March-3 and Long March-4.

China started development of modern carrier rockets in 1956, and Long March rockets have become the main carriers for China's satellite launching.

The Long March rocket family has already made more than 150 flights. The Shenzhou manned spaceships and China's lunar orbiters were all launched on the Long March rockets.

So far, China has three launch centers, located in Jiuquan, Taiyuan and Xichang.

Currently, a fourth launch center is being built in Wenchang in the island province of Hainan. The Wenchang launch center is expected to be put into use within two or three years, according to Yu.