A pair of satellites failed to reach their designated orbit due to abnormalities after lifting off from Xichang Satellite Launch Center in southwest China's Sichuan Province, according to the launch center on Thursday.

The satellites, known as DRO-A and DRO-B, were launched at 8:51 p.m. Beijing Time on Wednesday by a Yuanzheng-1S (Expedition-1S) upper stage aircraft, which was attached to a Long March-2C carrier rocket.

The first and second stages of the rocket operated as expected, but the upper stage encountered an abnormality during flight, causing the satellites to fail to accurately enter the preset orbit.

Efforts related to the relevant disposal work are currently in progress, said the launch center.

DRO, short for distant retrograde orbit, commonly refers to "a specialized orbital path around the moon that is of great significance for future deep space missions," according to NASA.

(With input from Xinhua)