BEIJING (AP) — Three Chinese astronauts returned to Earth Monday after a six-month stay aboard the Chinese plane. Tiangong Space Station.

A parachute slowed their capsule’s nighttime descent to a remote landing zone in China’s Inner Mongolia region. The crew emerged after landing at 1:24 a.m. A Chinese national flag stuck in the ground near the capsule flapped in the wind.

The Tiangong space station, completed two years ago, is part of China’s efforts to become a world leader in space exploration. In recent years, the country’s space program has brought back stones of the moon and landed a rover on Mars. Its goal is to send a person to the Moon by 2030, which would make it the second country after the United States to do so.

Space station astronauts returned after welcoming a replacement crew of three last week for the final six-month mission. The new crew will conduct experiments, perform spacewalks and install equipment to protect the station from space debris.

A space agency official said in April that Tiangong repeatedly maneuvered to avoid debris and partially lost power when the solar wing’s electrical cables were hit by debris, according to a report from the official Xinhua news agency.

China is among countries that have created space debris, including the rupture of a rocket stage in August during the launch of the first 18 satellites of a planned communications network similar to Starlink.

Tiangong, meaning Heavenly Palace, orbits the earth.

So far, only Chinese astronauts have traveled to the space station, but a space agency spokesperson said last week that China was in discussions to select and train astronauts from other countries to join missions, Xinhua reported.

Astronauts from several countries have traveled to the International Space Station, but China is blocked from accessing that program, primarily due to U.S. concerns about military involvement in China’s space program.