Honored guests attend the opening ceremony of an aerospace exhibition marking the 20th anniversary of Macao's return to the motherland at Macao University of Science and Technolocy in Macao, south China, Dec. 15, 2019. (Xinhua/Cheong Kam Ka)

Honored guests view exhibits at an aerospace exhibition marking the 20th anniversary of Macao's return to the motherland at Macao University of Science and Technolocy in Macao, south China, Dec. 15, 2019. The aerospace exhibition kicked off here on Sunday. Macao's first space exploration satellite was named Macao Science 1, the special administrative region (SAR)'s Secretary for Social Affairs and Culture Tam Chon Weng announced Sunday at the opening ceremony of the exhibition. (Xinhua/Cheong Kam Ka)

Visitors view exhibits at an aerospace exhibition marking the 20th anniversary of Macao's return to the motherland at Macao University of Science and Technolocy in Macao, south China, Dec. 15, 2019. The aerospace exhibition kicked off here on Sunday. Macao's first space exploration satellite was named Macao Science 1, the special administrative region (SAR)'s Secretary for Social Affairs and Culture Tam Chon Weng announced Sunday at the opening ceremony of the exhibition. (Xinhua/Cheong Kam Ka)

Visitors view exhibits at an aerospace exhibition marking the 20th anniversary of Macao's return to the motherland at Macao University of Science and Technolocy in Macao, south China, Dec. 15, 2019. The aerospace exhibition kicked off here on Sunday. Macao's first space exploration satellite was named Macao Science 1, the special administrative region (SAR)'s Secretary for Social Affairs and Culture Tam Chon Weng announced Sunday at the opening ceremony of the exhibition. (Xinhua/Cheong Kam Ka)