China's Shenzhou-8 has docked with the target orbiter Tiangcong-1 for the second time on Monday, marking the second successful docking between two unmanned spacecraft in orbit.

China's state-run news agency Xinhua reported that with the successful docking, de-linking and re-docking, as part of its current Shenzhou-8 space mission, China has laid a solid stepping stone for deep space exploration.

"Although China has been denied access to the ISS for two decades, Chinese technologists designed an androgynous docking system that allows any two similarly equipped spacecraft to dock with each other. Tiny adjustments could make the Chinese docking mechanism compatible with the ports of the ISS and U.S. space shuttles," the Xinhua report said.

On Nov. 3 Shenzhou-8, launched on Nov. 1, rendezvoused and docked with Tiangcong-1 for China's first ever space docking and the two have been orbiting together since then.

Early Monday, the two spacecraft were disengaged and then performed another successful docking about a half-hour later, Chinese space officials said.

The Beijing Aerospace Control Center (BACC), which commanded the Shenzhou-8 mission, called the re-docking a success. Following the re-docking, the coupled spacecraft will fly together for two more days before the scheduled return of Shenzhou-8 to earth.

Xinhua said the docking is a step towards China's goal of a manned space station by 2020. Two more docking missions are planned for 2012, with one to be conducted with Chinese astronauts, called Taikonauts, on board.

According to Xinhua, China's future space station will weigh about 60 tonnes and is set to be assembled in space around 2020, in time for the likely retirement of the ISS.