Long March 5 carrier rocket arrives at its launch pad to lift China's Tianwen-1 Mars probe at the Wenchang Space Launch Center in the southern island province of Hainan, July 17, 2020. Tianwen 1, a Chinese Mars probe, is set to be launched atop a Long March 5 carrier rocket in the coming days (Photo/China News Service)

Long March 5 carrier rocket arrives at its launch pad to lift China's Tianwen-1 Mars probe at the Wenchang Space Launch Center in the southern island province of Hainan, July 17, 2020.

Long March 5 carrier rocket arrives at its launch pad to lift China's Tianwen-1 Mars probe at the Wenchang Space Launch Center in the southern island province of Hainan, July 17, 2020.

Long March 5 carrier rocket arrives at its launch pad to lift China's Tianwen-1 Mars probe at the Wenchang Space Launch Center in the southern island province of Hainan, July 17, 2020.

Long March 5 carrier rocket arrives at its launch pad to lift China's Tianwen-1 Mars probe at the Wenchang Space Launch Center in the southern island province of Hainan, July 17, 2020.

Long March 5 carrier rocket arrives at its launch pad to lift China's Tianwen-1 Mars probe at the Wenchang Space Launch Center in the southern island province of Hainan, July 17, 2020.