The orbiter of China's Mars probe Tianwen-1 relayed high-definition images of the red planet's natural satellite Phobos on Saturday, which marks the two-year anniversary of the launch of the mission.

China launched the Tianwen-1 mission on July 23, 2020, sending an orbiter, a lander and a rover to the red planet. The orbiter entered the orbit of Mars in February 2021, and the lander and rover touched down on Mars and started operations in May 2021.

Mars has two small natural satellites, Phobos and Deimos (which mean fear and terror). 

Phobos is the innermost and larger of the two.

It's a small, irregularly shaped object with a mean radius of 11 km that orbits 6,000 km from the Martian surface in a near circular trajectory. It completes an orbit in just 7 hours and 39 minutes.

Recently, the Tianwen-1 operation team seized the timing when the orbiter was relatively close to Phobos and captured clear images of the satellite in its "full moon" state.

In the picture, Phobos is an irregularly shaped object like a potato. Streaks on its surface in the upper left might have been formed through impact. In the upper right is an impact crater, named Öpik after the Estonian astronomer and astrophysicist, with a diameter of about 2 km.