A pair of Chinese satellites failed to reach a planned orbit on their way to the moon after experiencing abnormalities, a rare setback for Beijing’s high-profile space programme.

The satellites, known as DRO-A and DRO-B, were launched on Wednesday evening from the Xichang Satellite Launch Centre in the Sichuan Province, the launch centre said in a press release on Thursday.

They were carried by A Yuanzheng-1S (Expedition-1S) upper-stage aircraft, attached to a Long March-2C carrier rocket, it said.

The first and second stages of the rocket operated normally, while the upper stage encountered an abnormality during flight, causing the satellites to fail to enter the preset orbit accurately, it said.

The relevant disposal work is currently underway, state-run Xinhua news agency reported, citing the launch centre.

The plan was for the two satellites to head towards the moon and enter a distant retrograde orbit (DRO).   

From there, they would fly in formation and work with DRO-L – a third satellite that was successfully placed into low-Earth orbit by a Jielong 3 rocket last month – to test laser-based navigation technologies between the Earth and the moon, known as cislunar space, the Hong Kong-based South China Morning Post reported.

The DRO orbit is at a high altitude, tens of thousands of kilometres above the lunar surface. It is highly stable, allowing spacecraft to remain on track for a long time without using fuel, and is an advantageous waypoint for research and exploration, according to Chinese scientists.

Long March rockets have been integral to China’s space ambitions, including moon missions.  China’s manned space station is currently in orbit.