Astronauts Fei Junlong and Nie Haisheng hurtled around the Earth yesterday aboard the nation's second manned spacecraft Shenzhou VI.

How do they keep themselves clean during the planned 119-hour space flight?

According to Dr Li Yongzhi, who is in charge of medical monitoring for astronauts, the two men cannot brush their teeth as they did on the Earth. Scientists prepared an oral cleanser similar to chewing gum, used after meals.

They also have a kind of tooth cover made of germfree gauze and a sort of edible toothpaste, which can also kill odor in the oral cavity, Li said.

"These approaches can make our astronauts more comfortable than their Russian peers, who use gauze soaked in saline to clean their teeth," Li said.

Since no shower is feasible in space, the two astronauts are provided with a special tissue to clean their bodies and a special cream to moisturize their skin. During the five-day flight, they will change their underwear once.

For astronauts, using the toilet has an entirely different space meaning. In a microgravity environment, flatulence, which contains flammable gases, like hydrogen and firedamp, can more easily ignite.

An astronaut can be blown away by his or her own intestinal gas, which can also pollute the air inside space capsules, according to Li Tanqiu, an aerospace expert.

Scientists have installed a "space toilet," and astronauts use a soft plastic hose and air-pumping device that conveniently sucks waste into a sealed container, said Li.

Traditional Chinese medicine has made a contribution to China's space mission, said Li. It can help with radiation effects and head congestion.