HELSINKI — China is preparing to launch its second space station cargo supply mission in mid to late September following delivery of a Long March 7 rocket to Wenchang spaceport.

The fourth new-generation Long March 7 arrived at Wenchang Satellite Launch Center, Hainan island, Monday, Aug. 16 after being transported by ship from Tianjin in north China, China’s human spaceflight agency announced.

The rocket will launch the roughly 13,000-kilogram Tianzhou-3 cargo spacecraft into low Earth orbit to dock with Tianhe, the core module for China’s space station. 

The mission is likely to launch around mid September, though China has not officially released a planned date of launch.

The Tianzhou-3 mission will provide supplies for the upcoming Shenzhou-13 crewed mission which is currently planned to launch in October. 

Preparations for that mission at Jiuquan, northeast China. The Long March 2F rocket for the mission has been readied in advance for use in the case of emergencies.

China launched Tianhe from Wenchang in late April. The Tianzhou-2 spacecraft docked with Tianhe May 29 before the arrival June 17 of the first crew aboard the ongoing Shenzhou-12 mission.

Tianzhou-3 will be the fourth of 11 missions set out for the construction phase of the Chinese Space Station. 

The 16.6-meter-long, 4.2-meter-diameter Tianhe (“harmony of the heavens”) will be joined in orbit by two further modules, named Mengtian and Wentian, in 2022. The pair are designed to host an array of experiments in areas including astronomy, space medicine, space life science, biotechnology, microgravity fluid physics, microgravity combustion and space technologies. 

The modules will host domestic and international science payloads. CubeSats can also be deployed from the orbital facility. The chief executive of Nanoracks said earlier this month the company had already lost business to China and its space station.

Tianhe provides regenerative life support and the main living quarters for astronauts as well as propulsion to maintain orbital altitude. 

The Shenzhou-12 crew of Nie Haisheng, Liu Boming and Tang Hongbo have been aboard Tianhe for 60 days, far surpassing the previous national record for human spaceflight mission duration of  33 days set by Shenzhou-11 in 2016.

The crew completed a first spacewalk July 4, installing foot restraints and an extravehicular working platform on Tianhe’s robotic arm and raising a panoramic camera. A further extravehicular activity is planned before the crew return to Earth in September.

The Shenzhou-12 mission is also carrying out a series of 14 space medical experiments, including use of a human system research cabinet aboard Tianhe. The crew conducted a magnetic levitation experiment earlier this month.

The Long March 7 is one of a number of new-generation kerolox and hydrolox rockets developed by China over the past decade. These include the Long March 5, 6, 7 and 8 series of rockets. 

The launcher is powered by 120-ton-thrust YF-100 and 18-ton-thrust YF-115 engines burning kerosene and LOX on the first, second and booster stages. 

Tianzhou cargo spacecraft have a mass of up to 13.5 tons and differing pressurized and unpressurized variants. Tianzhou-1 was launched in April 2017 to test technologies crucial to establishing and maintaining a space station. 

As well as cargo, experiments, supplies and spacesuits, Tianzhou-2 carried 1.95 tons of propellant into orbit for transfer to the 22.5-ton Tianhe module for maintaining orbit. 

A Beijing startup announced this month it is developing spacecraft which it hopes can provide flexible and cost-effective cargo services to and from the Chinese space station. The development follows a January call for proposals from China’s human spaceflight agency.

The Chinese space station is expected to operate in orbit for at least ten years. It will be joined in orbit by the Xuntian optical module, a co-orbiting Hubble-class space telescope. The space telescope will have a 2-meter-aperture comparable to Hubble but feature a field of view 300 times greater, allowing 40 percent of the sky to be surveyed across a decade.

Andrew Jones covers China's space industry for SpaceNews. Andrew has previously lived in China and reported from major space conferences there. Based in Helsinki, Finland, he has written for National Geographic, New Scientist, Smithsonian Magazine, Sky...