WENCHANG — China launched cargo spacecraft Tianzhou-3 on Sept 20 to deliver supplies for its under-construction space station.

The Long March-7 Y4 rocket, carrying Tianzhou-3, blasted off at 3:10 pm (Beijing time) from the Wenchang Spacecraft Launch Site in the southern island province of Hainan, according to the China Manned Space Agency (CMSA).

After 597 seconds, Tianzhou-3 separated from the rocket and entered its designated orbit. At 3:22 pm, the solar panels of Tianzhou-3 unfolded and began working properly.

The launch was a complete success, the CMSA said.

According to the CMSA, Tianzhou-3 will dock with the combination of the space station core module Tianhe and Tianzhou-2 cargo craft later.

The cargo ship carries nearly 6 metric tons of goods and materials, preparing for the upcoming launch of the Shenzhou-13 crewed mission.

The CMSA said Tianzhou-3 is loaded with living supplies for the astronauts, one extravehicular spacesuit for backup, supplies for extravehicular activities, space station platform materials, payloads and propellants.

On Sept 18, the Tianzhou-2 cargo craft separated from the rear docking port of Tianhe and docked with its front docking port. The CMSA said that the combination of Tianhe and Tianzhou-2 is in good condition, waiting for docking with the Tianzhou-3 cargo craft and the Shenzhou-13 manned spaceship.

The launch on Sept 20 is the 20th mission of China's manned space programs and the 389th mission of the Long March rocket series.

As the ancient Chinese said, to carry out an important task, supplies like rations and forage should go ahead of troops and horses. During the construction of the space station, cargo spaceships will always be launched ahead of crewed missions.

"We will transport support materials, necessary spare parts and equipment first, and then our crew," said CMSA Director Hao Chun.

Following the Tianzhou-3 mission, the Shenzhou-13 manned spaceship will be launched to dock with the core module Tianhe, and three astronauts will then begin their six-month stay in orbit.

China plans to complete the verification of key technologies and the in-orbit construction of the space station through multiple launches within two years.

Five launch missions are planned for this year, namely the launch of the Tianhe core module, Tianzhou-2 cargo ship, Shenzhou-12 crewed mission, Tianzhou-3 cargo ship and the upcoming Shenzhou-13 crewed mission.

Six more missions will come in 2022, including the launch of the Wentian and Mengtian lab modules, two cargo spacecraft and two crewed spaceships, to complete the construction of the space station.