Jiuquan, Gansu -- China successfully launched its third manned spacecraft on Thursday with three astronauts on board to attempt the country's first-ever space walk.

The spaceship Shenzhou-7 blasted off on a Long March II-F carrier rocket from the Jiuquan Satellite Launch Center in the northwestern Gansu Province at 9:10 p.m. after a breathtaking countdown to another milestone on China's space journey.

Onboard pilots Zhai Zhigang, Liu Boming and Jing Haipeng are expected to orbit the earth for three days, when one of them will float out of the cabin about 343 kilometers above the earth.

When they make it, China will become the third country in the world who is able to conduct extravehicular activity (EVA) in space following the former Soviet Union and the United States.

President Hu Jintao watched the historic moment at the launch center, joined by senior Communist Party of China (CPC) official Zhou Yongkang, Chinese space scientists and other work staff.

Hu congratulated experts and taikonauts on the successful launch of Shenzhou-7, which was declared about 22 minutes after the liftoff by chief commander Gen. Chang Wanquan of the manned space project.

"The successful launch marked the first victory of the Shenzhou-7 mission," Hu said in a brief speech after Chang announced the spacecraft entered the preset orbit.

He hailed the mission as "another feat on the Chinese people's journey to ascend the peak of science and technology", urging the staff to carry on their efforts to achieve a full-scale triumph.

It was China's third consecutive successful launch of a manned spacecraft since the country sent its first man into space in 2003. Two taikonauts flew in 2005.

From a screen at the BACC showing real-time pictures of the astronauts, the pilots, all 42 years old, looked calm during the launch, waving their hands to the camera from time to time. Zhai was seen flipping through the operation manual and making a gesture of victory with two fingers up.

Two of the trio would enter the orbital module, where one would put on domestically-made spacesuit Feitian and leave the module to take back test samples loaded outside, said Zhou Jianping, chief designer of the country's manned space project.

The other would wear a Russian Orlan suit and stay in the depressurized cabin for support, said Zhou.

"We wish we could fly freely in space just like Feitian on the ancient Buddhist murals, so we gave this name to the homemade spacesuit," said Zhou.

Feitian, which literally means flying in the sky, is the name of a legendary Buddhist goddess.

Other tasks of the Shenzhou-7 crew include the release of a small monitoring satellite and a trial of the data relay of the satellite Tianlian-I.

If successful, the mission would be of great significance to the country's future plans to build a space lab and a space station, said Zhang Jianqi, deputy chief commander of the manned space project.

"China pursues the principle of making peaceful use of space in its exploration and development," Zhang told Xinhua, saying the country was willing to carry out various forms of international cooperation in space exploration.

The country has announced that its manned space program is being carried out in three stages, which eventually lead to the establishment of a permanent space station.

The planned space walk during the Shenzhou-7 mission will be one key step of the program's second stage, which also involves the docking between capsule and space module and establishment of a space lab.

China has made a series of technical breakthroughs for the Shenzhou-7 project, including the independent research and development of the world's most expensive EVA suit, which costs 30million yuan (about 4.4 million U.S. dollars) each, scientists said.

Among other highlights were a new airlock module that didn't appear in the previous six flights and a safer, more comfortable rocket with 36 technological improvements.

The spaceship is scheduled to land in the central region of north China's Inner Mongolia Autonomous Region after completing the task.

As millions of Chinese glued their eyes to the live broadcast of the Shenzhou-7's launch, people in Inner Mongolia couldn't wait for its return.

"I am proud that the Shenzhou spacecraft will land near my home. I hope I could do something for it," herdsman Qi Qingtu said.

In 2005, the magnetic recorder, or "black box" of the Shenzhou-6, was first sighted by a herdswoman in Otog Banner in the autonomous region, which fell on the pasture just 1.5 kilometers away from her home.

World attention on China's leap forward in space boosted the nation's pride, as 13 journalists from 10 overseas media agencies such as Reuters and Associated Press covered Shenzhou-7's takeoff at Jiuquan on Thursday night, the first time China allowed overseas media to report at the launch site.

Senior CPC leaders Wu Bangguo, Jia Qinglin, Li Changchun, Xi Jinping and Li Keqiang watched the launch at the BACC, while astronomic buffs took the chance to track and watch the spacecraft with telescopes and cameras.

"The launch shows how advanced our country's space technology is," said 65-year-old Zhang Jizhong in Zhengzhou, capital of central China's Henan province, after watching television for about five hours.

For Chen Lin, a Beijing-based linguistic professor, the fact that foreign media increasingly referred to Chinese astronauts as "taikonauts", a term coined on the basis of the Chinese term "taikongren" (literally means spaceman in Chinese), was a signal of China's growing global influence.

"This shows that China is exerting more global influence in terms of its science and technology powers," said Chen. "The country has more to export to the world than just kungfu and Chinese food."

China's Shenzhou-7 manned spacecraft and three astronauts on board will have to pass six key tests to fulfill their mission, said Zhou Jianping, the program's chief designer, in Jiuquan, Gansu province, Thursday.

TEST 1: BLASTOFF

"For any manned space program, the possibility to come across deadly failures is larger during the launch," said Zhou at the Jiuquan satellite launch center of northwestern Gansu Province.

Although the Long-March II-F carrier rocket, to carry the spaceship, had succeeded in bringing six spacecraft to the outer space, a series of contingency plans were made to protect the safety of astronauts, he said.

The 100-meter-high launch tower is equipped with a slide to facilitate astronauts escape from the spaceship when an accident happens.

The control center is 1,500 away from the launch tower in a bid to reduce threat to the ground staff.

Eight contingency modes were designed for the spaceship during the ascent stage, four inside the atmosphere and the other four out of it.

"Jiuquan Satellite Launch Center is confident of a successful blastoff for it has successfully launched more than 100 satellites and spacecraft in the past five decades. We have the world's latest technologies and management," said Cui Jijun, the launch center director.

TEST 2: TRANSFER THE ORBIT

The Shenzhou-7 spaceship will transfer from an elliptic orbit to a circular one in its fifth circle around the earth. Whether it will succeed in this stage will be critical for the spaceship to fulfill all its tasks and land on the scheduled landing area in the timetable, said Zhou.

The spaceship will first travel on the elliptic orbit, 200 km away from the earth at the nearer point and 350 km at the farthest point, and it will transfer to the circular orbit 343 km away from the earth, to make its return trip easier.

Beijing Aerospace Control Center will take in charge of controlling the spaceship at this stage. "We are confident of fulfilling this task as we have performed well in the country's first moon probe mission," said Zhu Mincai, the center's director.

TEST 3: PUT ON SPACE SUIT

Astronauts will start preparing for the spacewalk in the spaceship's ninth circle around the earth. The most important part is to put on the space suit. The whole preparation will take about14 hours.

Chinese only spent four years in developing its own EVA (extra vehicular activity) suits, named Feitian.

Despite repeated training, it will be the first time for the astronaut to put on it in the outer space. The astronaut must strictly follow the procedure. Any mistake will lead to deadly results, said Zhou.

"It will be much different to put on it in the space from doingit on the earth," said Liu Boming, one of the three astronauts to be on board, "But I can only tell you what is the difference when I am back."

TEST 4: AIRLOCK

The airlock, a pressure chamber linking the main body of the spaceship to the outside, is new on Shenzhou-7 and was not required on the previous six space flights. Whether it will work properly decides whether the astronaut can finish the spacewalk.

Inside the airlock, the air pressure will reduce to zero before the astronaut steps outside and restore to the normal level inside the module after he returns. The whole procedure must finish within a certain period of time.

"The airlock is well designed and safe," said Zhang Bonan, chief designer of the manned spacecraft system.

TEST 5: SPACEWALK

The highlight of the whole program will be the 30-minute spacewalk when the Shenzhou-7 travels around the earth in the 29thcircle.

It will be a test for both the astronauts and the ground staff. The astronaut that walks into the space will take test samples from the surface of the modules and solar battery, cooperating with another astronaut inside. The ground staff must maintain the communication between the control center and spacecraft and provide supports for the astronaut.

Every move must be well done, including opening the door of there-entry module, closing it and sealing it. "It is not easy to do it in the outer space," Zhou said. "If the door is not sealed, there will be a disaster."

"In such an independent task as the spacewalk, it is the psychological factor that affects the astronaut's performance," said Yang Liwei, China's first spaceman and deputy director of the China Astronaut Research and Training Center.

TEST 6: BLACKOUT AREA

When the spaceship begins its journey back, it must start its engine at the right time for a second earlier or later will lead to a landing site 9 km away from the planned one.

The re-entry module will go through a "blackout" area when it re-enter the atmosphere, which means all communication with the ground will be weak and even cut off. It will greatly challenge the physical and psychological conditions of the astronauts.

The blackout will disappear when the module reaches the height 40 km from the ground.

"The landing system will search the module and rescue the astronauts as soon as they land. We will try our best to give a perfect end to the mission," said Sui Qisheng, director of the landing system.