BEIJING — Chinese astronauts plan to execute their country’s first manual space docking maneuver on June 24, six days after the automatic docking of their Shenzhou 9 spacecraft allowed them to move into the Tiangong orbital laboratory.

The June 18 transfer was the first time that astronauts had floated from one Chinese spacecraft to another.

While state media are trumpeting the success of the automatic docking maneuver, which was not China’s first, the chief engineer of the manned spaceflight program stresses that the planned manual docking, not previously attempted by Chinese astronauts, is the key challenge.

“The real test will be the manual docking attempt six days later,” chief engineer Zhou Jianping tells Xinhua news agency. “A manual docking, if successful, will demonstrate the country’s grasp of essential space rendezvous and docking know-how. It will mean China is fully capable of transferring humans and cargo to an orbiter in space.”

A Long March 2F rocket launched Shenzhou 9 on June 16. The Beijing Aerospace Control Center says it needed only four orbital corrections, instead of the planned five, to align the capsule with the 8.5-metric-ton Tiangong 1, which was launched last year.

Shenzhou 8 executed China’s first space docking maneuver without astronauts aboard last year.

With the two spacecraft flying at 7.8 km per second relative to the Earth, ground controllers maneuvered Shenzhou 9 into four positions, each successively closer to Tiangong 1, after which automatic systems took over and brought them together. Microwave and laser radars supplied positioning data for the maneuver, but the astronauts, including China’s first female spacefarer, were ready to take manual control.