BEIJING - China is studying how to retrieve and reuse manned spacecraft in its future missions, the chief engineer of the nation's manned space program said on Sunday.

"It's our next goal to reuse manned spacecraft. We want to make our space exploration cost-effective," Zhou Jianping said, as China marks Space Day, newly designated by the government to commemorate China's first satellite launch on April 24, 1970.

Reusable manned spacecraft are a Holy Grail of space exploration. The United States developed partially reusable manned spacecraft capable of reaching low Earth orbit. But they were all retired in 2011 due to high costs and risks, including an accident in 2003 that killed seven astronauts.

Zhou did not go into any more details on the project, but stressed his team's focus on saving costs, giving an example from the Tiangong space lab series.

Tiangong-1 was due to be followed by Tiangong-2 and Tiangong-3, but Chinese scientists managed to incorporate all tasks planned for the third generation of the lab into Tiangong-2, he said. There has been no need to develop Tiangong-3.

And China's space station, to be completed around 2022, will be a "green model, with highly advanced and budget-saving facilities in flight control, power supply and waste recycling", according to Zhou.

Earlier this month, US rocket developer SpaceX achieved a world first by landing one Falcon rocket on a carrier at sea.

China was paying close attention to such innovation and was testing its own reusable rockets, promising a breakthrough before the end of 2020, according to earlier reports.