The Shenzhou XVIII astronauts on board China's orbiting Tiangong space station completed a host of assignments in recent days, including an emergency response exercise, according to China Central Television.

The State broadcaster reported on Sunday that after the crew's second spacewalk on July 3, mission commander Senior Colonel Ye Guangfu and crew members Lieutenant Colonel Li Guangsu and Lieutenant Colonel Li Cong undertook tasks such as replacing an old experimental device with a new one and finishing a series of mental health assessments.

The report said the crew also conducted an "all-system emergency response exercise" in cooperation with ground controllers.

During the exercise, Ye's team was tasked with reacting to a scenario in which the space station had been hit by space debris and was beginning to lose pressure.

After the pressure alarm rang, the astronauts checked the alarm status and determined what actions should be taken. They donned oxygen masks before trying to find possible leaks.

With ground controllers' assistance, the crew soon sealed all "leaks", CCTV said.

The Shenzhou XVIII astronauts — the seventh group of inhabitants of the Chinese space station — were launched on April 25 by a Long March 2F carrier rocket from the Jiuquan Satellite Launch Center in northwestern China. They arrived at the Tiangong space station the next morning to take over from their Shenzhou XVII peers.

They have performed two spacewalks: to install space debris shields and check the condition of extravehicular equipment.

With nearly half of their space journey complete, the astronauts will spend the rest of their stay carrying out many scientific experiments and technological tests, according to the China Manned Space Agency.

Completed in late 2022, Tiangong is one of the largest and most complex structures ever established in space by humanity.

Orbiting Earth at a distance of about 400 kilometers, the Chinese station has three permanent parts — a core module and two science capsules — and is regularly connected to several visiting crew and cargo spaceships.