In south China's Shenzhen, 4 volunteers -- three men and one woman -- have emerged from a sealed space capsule where they were living for 180 days.

The experiment is a survival mission to test how people fare physically, psychologically, and emotionally, in a sealed ecological life-support system. It simulates how people might travel for prolonged periods in space.

The volunteers tended to 25 varieties of plants, including wheat, potatoes, sweet potatoes, soy beans, peanuts, lettuce, and cabbage. The four -- all scientists -- are testing whether humans can rely on recycling food, water, and oxygen. They were living in a 370 square meters space.

They also lived on Mars time throughout the experiment, with days lasting 24 hours and 40 minutes. The four volunteers shared their feelings in a news conference right after they emerged from the capsule.

"My deepest impression was a book I read in the capsule, which is Mars 500. There is a sentence in it that says "any joy a space scientist gets from success lasts only as long as a cup of tea, because there are more works waiting for them. It's the same situation with us. There are more experiments ahead for us. Our time to celebrate is too short," said Luo Jie, volunteer.

"As an astronaut instructor, this experiment offers me an opportunity to experience what life in space is like in advance. And I was able to learn before I teach it to my students. It's very helpful for my future work," said Tong Feizhou, volunteer.