Photo taken on Nov. 14, 2019 shows the trial ground of an experiment for landing on Mars in Huailai County, north China's Hebei Province. China on Thursday unveiled an experiment simulating the process of a probe hovering, avoiding obstacles and descending to land on Mars. China plans to launch the Mars probe in 2020, aiming to complete orbiting, landing and roving in one mission, an unprecedented achievement, according to the China National Space Administration. How to safely land on Mars is one of the biggest challenges facing the mission. The experiment simulated the gravity of Mars, about one-third of the gravity on Earth, to test the design of the lander. (Xinhua/Jin Liwang)