Astronauts on Chinese space station home after being stranded by debris impact.

Three veteran Chinese astronauts are home after being stuck for more than a week longer than planned aboard the Tiangong space station. Their return capsule was hit and damaged by space debris fragments. 

China's space agency has not revealed how badly damaged the capsule was, and it’s not known if the craft was hit by debris while in flight or while docked at the station. No one was injured. The Shenzhou-20 spacecraft remains attached to Tiangong, a permanently crewed space station operated by China Manned Space Agency. 

Officials had ordered the astronauts to remain on Tiangong while engineers troubleshoot the capsule. Without a way to repair it remotely, another capsule docked at the station, Shenzhou-21, became the return vessel for the Shenzhou-20 crew, which arrived in China on Nov. 14.

A backup Shenzhou craft will be sent for the Shenzhou-21 crew. 

The Shenzhou spacecraft ‒ made up of an orbital module, a reentry module and a service section ‒ carries three astronauts and equipment to Tiangong after launching via a Long March 2F rocket. The Shenzhou-20 mission launched on April 24 from Jiuquan Satellite Launch Center in northwest China.

Who are the Shenzhou-20 Chinese astronauts?

The three Shenzhou-20 astronauts are Chen Dong, Chen Zhongrui and Wang Jie. Combined, the three men have amassed more than 800 days in space. They were scheduled to return to Earth on Nov. 5 after a six-month mission aboard the station. 

This is the third Shenzhou mission for Commander Chen Dong. 

After the Shenzhou-20 vessel could not be repaired aboard Tiangong, safety protocols established the Shenzhou-21 as the return vessel for the Shenzhou-21 crew. A backup Shenzhou craft for the Shenzhou-21 crew, now more than a week into their six-month rotation, will be sent from the Jiuquan Satellite Launch Centre.

The Shenzhou program takes Chinese astronauts to and from Tiangong for rotating six-month stays, where they perform a variety of tasks.

How big is the Tiangong space station?

Both Tiangong and the International Space Station orbit the Earth at the same general altitude. Tiangong’s orbit is 210 to 280 miles high, while the space station can range from 230 to 285 miles with reboosts. 

Tiangong, which means "Heavenly Palace," supports three astronauts, with room for three more during crew rotations. 

How was the Chinese spacecraft damaged?

Space debris, usually old satellites and rocket fragments, moves at very high speeds. It can pose a risk to space stations, which are capable of performing avoidance maneuvers and other steps to protect equipment. 

The Tiangong delay is the first time a return mission has been postponed by space debris, Reuters reported. 

It comes more than a year after an ordeal involving the crew of the Boeing Starliner, who were stranded aboard the space station for 10 months. NASA astronauts Butch Wilmore and Suni Williams returned safely to Earth on March 18. 

(This story has been updated with new information.)

Contributing: Eric Lagatta, George Petras and Ramon Padilla

SOURCES Reuters, Agence-France Presse