China launched the Tianzhou 3 cargo spacecraft on Sep 20 to deliver more supplies to the Tiangong space station and ensure that three astronauts who are scheduled to spend a record-breaking six months on it can live and work comfortably.
A 53-meter Long March 7 rocket, carrying Tianzhou 3, blasted off from the Wenchang Space Launch Center on the coast of the southern island province of Hainan at 3:10 pm.
The spacecraft entered a low Earth orbit, unfolded its solar panels at 3:22 pm and began to execute the rapid autonomous rendezvous and docking procedures with Tianhe, the space station's core module, China Manned Space Agency said in a statement.
Tianzhou 3 is the second cargo spacecraft sent to Tianhe, during the construction phase of the station. A series of Tianzhou robotic cargo spacecrafts will be produced to allow for more frequent deliveries of supplies in the future, said Deng Kaiwen, assistant to the chief commander of Tianzhou 3.
The Tianzhou crafts will also focus on using China's Beidou Navigation Satellite System to make docking procedures with Tianhe more precise, Deng from the Fifth Research Institute of China Aerospace Science and Technology Corporation, said.
In October, a second group of three astronauts is scheduled to be sent to Tianhe in the Shenzhou XIII crewed spacecraft. They will spend twice the amount of time in the space station as their predecessors, who returned to earth safely on Friday after spending 90 days living and working in the core module, the longest stay in space by Chinese astronauts, according to CMSA.
Compared with items delivered by Tianzhou 2 in late May, there is a greater variety of goods onboard Tianzhou 3 to support the operation of the space station. The supplies include essential items for the astronauts as well as spare parts for the space station, Deng said.
"To accommodate the needs of the astronauts who will stay longer, Tianzhou 3 has carried 40 percent more drinking water than Tianzhou 2. Meanwhile, we have removed four propellant storage units to make more room. Tianzhou 2 carried two tons of propellant while Tianzhou 3 will only send 750 kilograms to Tiangong. But it can fully support the missions related to Tiangong during its construction phase," Deng said.
He added that as the second crew will celebrate a number of festivals on the space station, including Spring Festival, there might be special treats onboard.
Tianzhou 3 and its supplies were tested for COVID-19 before the spacecraft was sealed on Aug 2 to ensure the astronauts are not at risk of infection, he added.
The Tianzhou 2 robotic cargo spacecraft changed a docking hatch with the Tiangong space station on Saturday, according to the CMSA. Tianhe and the cargo spacecraft were in good condition, it said, noting the orbiting pair will soon welcome Tianzhou 3.
"Then Tianhe will have two cargo spacecraft attached to it at the same time. The new crew will still have missions to be carried out in Tianzhou 2 before it can be disposed of," Deng said.
A Tianzhou cargo spacecraft has two parts－a cargo cabin and a propulsion section－and can transport up to 6.9 metric tons of supplies.