The satellites were carried by a Long March 3B rocket that lifted off at 11:26 am from the Xichang Satellite Launch Center in Sichuan province and were deployed into a medium-Earth orbit. They are the 13th group of third-generation BeiDou satellites operating in medium-Earth orbits and the first deployed in such an orbit since the completion of the BeiDou global system, the office said in a news release. The two spacecraft will come online after a period of in-orbit technical verification, it said.

Compared with their predecessors in medium-Earth orbits, the new craft features better capabilities in terms of messaging capacity, timing accuracy and equipment automation, the release said, noting that their service will improve the BeiDou system's reliability and functions.

Pang Zhihao, an expert on space exploration technology who worked at the China Academy of Space Technology for decades, said that the addition of new satellites with upgraded capabilities promises a long life and higher stability for BeiDou.

Read more in Space Daily article.