These are low altitude escape, high altitude escape and rocket-spaceship emergency separation, said Zhang Zhi, leading designer of the Long March II F rocket, on Wednesday.

The low altitude escape covers the period from 30 minutes before take-off to 2 minutes after take-off, including escape from the launch pad. Escape is realized by what is known as "escape tower", an 8-meter-long device like a huge lightening arrester on top of the rocket.

The boosting stage is the time zone with the biggest probability of trouble with spaceship. The most dangerous points are at about 52 seconds, when the pressure of current separation is the biggest and at about 68 seconds, when the air resistance is the biggest, Zhang said.

When trouble occurs at these dangerous points, the escape craft that obtains power from the escape tower will drag the spaceship away from the rocket. The work principles of the other escapes are similar to the low altitude escape.

If trouble occurs about 200 seconds after lifting, high altitude escape would apply. Four escape engines and two high altitude separation engines will supply power to the cowl, which will separate the spaceship from the rocket. If trouble occurs at about 584 second point, spaceship-rocket emergency separation may apply, Zhang said.

After the escape succeeds, the escape device will land within an 800 km area from the Badanjilin Desert in Inner Mongolia to Yulin of Shaanxi Province. Then the rescue team of the Jiuquan Satellite Launch Center will send out helicopters to search the area.

"The escape system for Shenzhou V is exquisitely designed," Zhang said, "But this is a system we least hope to use."

(Xinhua News Agency October 15, 2003)