China launched its longest manned space mission , sending two astronauts into orbit to spend a month aboard a space laboratory that is part of a broader plan to have a permanent manned space station in service around 2022.

The Shenzhou 11 blasted off on a Long March rocket at 7:30 am (2330 GMT) from the remote launch site in Jiuquan, in the Gobi desert, in images carried live on state television.

The astronauts will dock with the Tiangong 2 space laboratory, or “Heavenly Palace 2”, which was sent into space last month. It will be the longest stay in space by Chinese astronauts.

Shenzhou 11 is the third space voyage for Jing, who will command the mission and celebrate his 50th birthday in orbit. In a manned space mission in 2013, three Chinese astronauts spent 15 days in orbit and docked with a space laboratory, the Tiangong 1.

Advancing China’s space program is a priority for Beijing, with President Xi Jinping calling for the country to establish itself as a space power. China insists its space program is for peaceful purposes.

Shenzhou 11, whose name translates as “Divine Vessel”, will also carry three experiments designed by Hong Kong middle school students and selected in a science competition, including one that will take silk worms into space.

The U.S. Defense Department has highlighted China’s increasing space capabilities, saying it was pursuing activities aimed at preventing other nations using space-based assets in a crisis.