Despite becoming a bit thin and losing some of his hair, Wang Yue looks cheerful.

After spending 520 days in a mock-up spacecraft, plus one month for extended experiments, the only Chinese volunteer in the Mars-500 program returned to Beijing on Tuesday.

"If I have a chance to do it all over again, I'm willing to do it," said the 29-year-old native from Nanjing, East China's Jiangsu province.

"But I will probably improve my communication skills in Russian, make a better plan for physical exercise and get my lost hair back."

Between June 3, 2010, and Nov 4, 2011, he and three Russians, one French and one Italian spent 18 months in an isolated experimental facility in Moscow to test how human beings respond to the pressures of a there-and-back voyage to Mars.

Dressed in a black leather jacket, blue jeans and wearing a gray wool scarf, the young man received an ovation upon his arrival at Beijing Capital International Airport.

Hundreds of hours of recordings in the experimental facility and large numbers of samples taken from him will help scientists of China's manned space program understand the physical and psychological strains during extended space travel.

"As Chinese astronauts will stay six to 12 months in the space station (slated for 2020), the findings will be of use," Bai Yanqiang, deputy director of the Astronaut Center of China, said in an interview on Tuesday.

He said that while Wang survived the psychological challenges, all six volunteers in the program experienced emotional fluctuations and strains in human relationships.

For Wang, the clearest reflection of the strains may be all the hair he lost, which he hoped to get back.

He also lost 10 kilograms of weight.

"The 520 days are really not easy to get through. My physical and psychological conditions went up and down, like waves," the articulate young man said in a soft voice.

"It's impossible to stay happy all the time. After all, I'm human, not a robot. So I tried hard to adjust my mood. You've got to make yourself happy and feel good."

He practiced calligraphy to calm himself down, taught others Mandarin and celebrated Chinese festivals and events to give the dull life in the facility a little flavor.

And even with good-natured ribbing, he and others found the last half of the journey intolerable.

"On the way back, there were just more repeated tests, which are really a test of one's willpower," he said, adding they did the designated 105 tests many times in the first 250 days.

In addition, there were culture shocks, he said.

"But the good thing is, if we had different ideas, we would all speak out. The team leader got the last say. The next day, all unhappiness due to different opinions, if any, would be all over. This is the important factor that supported us through the 520 days," he said.

For the rest of this month he will go through medical checkups and recovery training, among other tasks, like eating the Chinese food he missed so much during the experiment.

"I will get my weight back soon," he said.