China's spacecraft tracking ship Yuanwang-3 sails in the waters near the equator on June 19, 2019. Yuanwang-3 has crossed the equator at 23:09 Tuesday Beijing Time (1509 GMT Tuesday) and continued its sail for the southern Pacific Ocean for upcoming satellite maritime monitoring missions. (Xinhua/Liu Shiping)

China's spacecraft tracking ship Yuanwang-3 sails in the waters near the equator on June 18, 2019. Yuanwang-3 has crossed the equator at 23:09 Tuesday Beijing Time (1509 GMT Tuesday) and continued its sail for the southern Pacific Ocean for upcoming satellite maritime monitoring missions. (Xinhua/Li Yuze)

China's spacecraft tracking ship Yuanwang-3 sails in the waters near the equator on June 18, 2019. Yuanwang-3 has crossed the equator at 23:09 Tuesday Beijing Time (1509 GMT Tuesday) and continued its sail for the southern Pacific Ocean for upcoming satellite maritime monitoring missions. (Xinhua/Li Yuze)

China's spacecraft tracking ship Yuanwang-3 sails in the waters near the equator on June 18, 2019. Yuanwang-3 has crossed the equator at 23:09 Tuesday Beijing Time (1509 GMT Tuesday) and continued its sail for the southern Pacific Ocean for upcoming satellite maritime monitoring missions. (Xinhua/Li Yuze)