For the first time, an orbiter China sends into space has a completely new mission: to rendezvous and dock with another one. At 5:58 a.m. Tuesday, a 58.3-meter-long upgraded Long March-2F rocket, carrying unmanned spacecraft Shenzhou-8, blasted off from the Jiuquan Satellite Launch Center in the northwestern Gobi desert and thundered skyward.

About 20 minutes after launch, Shenzhou-8 reached its orbital speed. At this point, it was trailing Tiangong-1 by nearly 10,000 kilometers. The chase toward rendezvous and docking was on.

The chase spacecraft is expected to catch up with Tiangong-1, or "Heavenly Palace," China's first space lab module within two days after the launch for the country's first docking. The technology is crucial to building a space station.

Before Shenzhou-1 approaches Tiangong-1, it will need to have five orbital changes and four "brakes" during a 1.3-million-km journey.

Tiangong-1, the target orbiter, was lowered to the 343-km-high rendezvous and docking orbit and adjusted itself to fly invertedly on Sunday under the control of the Beijing Aerospace Flight Control Center.

Tiangong-1 has already been in low Earth orbit for more than a month. It was launched into space on Sept. 29.

Chinese space technologists have made "considerable modifications" to previous versions of China's unmanned spacecraft to enable Shenzhou-8 to dock with a target orbiter, a spokeswoman for China's manned space program said on Monday.

"More than half of the 600 or so sets of equipment have been modified, while newly designed devices account for about 15 percent of the total," spokeswoman Wu Ping said.

The modifications were mainly aimed at arming the spacecraft with automatic and manual rendezvous and docking capacities, and to enhance the vehicle's performance, safety and reliability, the spokeswoman said.

"After the improvements, the spacecraft will be able to connect with the target orbiter Tiangong-1 for 180 days," Wu said.

Source: Xinhua News Agency