This photo taken on June 17, 2021 at Beijing Aerospace Command and Control Center shows China's Shenzhou-12 manned spaceship docking with the front docking port of the space station core module Tianhe, forming a three-module complex with the cargo craft Tianzhou 2. (PHOTO / XINHUA)

The Shenzhou XII spacecraft departed China's Tiangong space station on Thursday morning, according to the China Manned Space Agency. The spacecraft, which is carrying three Chinese astronauts, is to land on Earth on Friday.

The agency said in a brief statement that the spacecraft left the station's core module at 8:56 am and started to orbit Earth on its own.

The three-month-long Shenzhou XII mission, the nation's seventh manned space trek, is part of the Tiangong program, which aims to complete a three-component station in low-Earth orbit before the end of 2022

Before their departure, the astronauts — Major General Nie Haisheng, the mission commander, Major General Liu Boming and Senior Colonel Tang Hongbo — configured the space station, transmitted some experimental data back to ground control and arranged materials inside the station, according to the statement.

By Thursday morning, the crew had been in space for 90 days, almost three times longer than the Shenzhou XI mission, in which their peers Jing Haipeng and Chen Dong spent 33 days in orbit.

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Shenzhou XII was launched on a Long March 2F carrier rocket that blasted off on June 17 from the Jiuquan Satellite Launch Center in northwestern China. The astronauts entered Tiangong later that day, becoming the first inhabitants of the station.

Major General Nie Haisheng, the Shenzhou XII mission’s commander, and Major General Liu Boming are seen waving to the camera during the crew’s second extravehicular activity, commonly known as a spacewalk, on Sept 10, 2021. (XU BU / FOR CHINA DAILY)

During the mission, the astronauts carried out two extravehicular activities, or spacewalks, using a large robotic arm and other equipment to install and adjust devices outside the station.

The three-month-long Shenzhou XII mission, the nation's seventh manned space trek, is part of the Tiangong program, which aims to complete a three-component station in low-Earth orbit before the end of 2022.

READ MORE: Shenzhou-12 astronauts enter space station core module

Upon its completion, Tiangong, or "Heavenly Palace", will be manned regularly by groups of three astronauts in periods lasting several months. During handovers to new three-member crews, the station will accommodate up to six astronauts.