China launched two satellites into space yesterday, the latest additions to its burgeoning Beidou global navigation and positioning network.
It was the first time the nation successfully launched two navigation satellites on one rocket into a medium-high earth orbit of about 20,000 kilometres - a difficult feat.
Professor Jiao Weixin, from Peking University's School of Earth and Space Sciences, said the mission required greater transport ability and technical precision. 'China has previously launched three satellites on one carrier rocket' into geostationary orbit of about 36,000 kilometres, he said.
But those were lighter balloon satellites inflated with gas after being sent into orbit, and they did not have to be so carefully aligned.
'That was not as technically challenging as this mission,' said Jiao.
Xinhua reported that the Long March-3B rocket, carrying the network's 12th and 13th satellites, blasted off from the Xichang Satellite Launch Centre in Sichuan just before 5am.
Jiao noted that the launch of two navigation satellites at once shows how China is picking up the pace of developing Beidou, in a push to compete in satellite navigation - a field largely dominated by the United States' Global Positioning System (GPS), Russia's Glonass and Europe's Galileo.
The two satellites will help improve the accuracy of the Beidou - or 'Compass' - system, Xinhua quoted the launch centre as saying.
The centre said China would launch three more satellites for the network this year, and that a global satellite positioning and navigation system would be completed in 2020 with more than 30 satellites.
Yesterday's mission marked the 160th flight of the Long March series of carrier rockets.
Though Beidou is still incomplete, the central government said last year that the system had already proven its worth in enhancing the country's military, and in making the nation technologically and economically stronger.
Beijing views an independent satellite navigation system as important to national security.
Retired general Xu Guangyu, now a senior researcher at the China Arms Control and Disarmament Association, previously told the South China Morning Post that Beidou would significantly increase China's military strength and political influence around the world.
Without its own GPS, Chinese troops and naval vessels have had to depend heavily, if not entirely, on America's network, Xu said. The US military could - and had - manipulated the signals and threatened China's national security, he said.