BEIJING » China’s space program on Friday called the recovery of an unmanned spacecraft that docked twice with an orbiting module a major step toward a future space station, and said it remained open to cooperation with other nations despite U.S. objections.

The Shenzhou 8 craft parachuted to the ground in China’s western desert late Thursday after more than two weeks in space. It docked twice with the Tiangong 1 module, which remains in orbit, during a mission proving China capable of successfully docking by remote control. Early U.S. astronauts did so manually.

"It represents a major breakthrough for our country’s space rendezvous and docking technology program," said Wang Zhaoyao, deputy director of the China Manned Space Engineering Office.

Although China is developing its space station on its own, Wang said China welcomed outside involvement on the basis of "mutual respect, mutual benefit, transparency and openness."

"We welcome colleagues and experts in the space field to join us in developing and operating this space station so that we can together make greater contributions to manned space flight and the peaceful use of space," Wang told reporters at a news conference discussing the Shenzhou 8 mission.

China will conduct two more space docking missions next year, one of them possibly manned, and plans to complete a manned space station around 2020. At about 60 tons, the Chinese station will be considerably smaller than the 16-nation International Space Station.

China has made steady progress toward a space station since a 2003 launch that made it only the third nation to put a man in space. Two more manned missions have followed, and China separately seeks to launch a lunar rover next year.

The country launched an independent space station program after being rebuffed in its attempts to join the ISS, largely on objections from the United States. The U.S. is wary of the Chinese program’s military links and the sharing of technology with its chief economic and political rival.

Despite that setback, China has refused to rule out future participation in the ISS, a willingness Wang reiterated Friday, and says its craft could dock with the ISS and spacecraft of other nations with only minor adjustments.

Wang said none of the eight Shenzhou missions have had direct military application, but conceded that the space program included many technologies such as communications satellites that could also be utilized by the military. Such so-called dual-use technologies are a common feature of the American and other space programs.

As a major player in science, China needs to independently master space technologies, Wang said, but he added that "independent development does not mean isolated development."

"China stands ready to carry out exchanges and cooperation with other countries in this field," he said.

Already, China has had limited but fruitful engagement in space cooperation with Russia, Germany, France and other nations, Wang said. He said the Shenzhou 8 landing allowed the recovery of 17 biological experiments carried out with Germany in the docking vehicle.