A 42-year-old fighter pilot whose mother sold sunflower seeds on the street to pay for his education is to become China’s first man to walk in space.

Zhai Zhigang, who holds the rank of colonel in the People’s Liberation Army, will join two other astronauts on board the Shenzhou VII for China’s third manned space mission when it blasts off on September 25 for a 68-hour flight.

Already security has been tightened for miles around the Jiuquan Satellite Launch Centre in the deserts of northwestern Gansu province in preparation for the historic mission. Paramilitary police and soldiers are manning extra roadblocks, all cars and their passengers are being checked and only those with special passes are allowed to enter the security zone.

Launch is scheduled for between 8pm and 9pm on September 25 with the spacewalk by Colonel Zhai expected to take place in the afternoon or evening of September 26 or 27, the State Council, or cabinet, said.

He will undertake a 40-minute manoeuvre outside the spacecraft and will release a small satellite that will broadcast video images of his walk outside the craft. One of his two colleagues, both aged 42 and both fighter pilots, will accompany him into the vacuum chamber to help him to change into his enormously heavy pressurised spacesuit, which cost some 100 million yuan (£8 million) and is based on Russian designs. He will be linked to the spacecraft by two lifelines that will supply oxygen and communications.

Colonel Zhai, who is married with one son, has been preparing for this day for more than a decade and just missed being selected to become the first Chinese to go into space in 2003. China became the third country to put a man in space five years ago when Yang Liwei orbited the Earth in a solo mission. Colonel Zhai was on a shortlist of three.

He was born in October 1966, just months after the start of the chaotic ultra-leftist Cultural Revolution, in a small community near the town of Qiqihar in northern Heilongjiang province near the border with Russia. When he was a boy his illiterate mother would spend all day selling sunflower seeds - a popular Chinese snack - on the streets to make enough money to pay for an education for her children.

One media report said she was even more delighted than her son when she heard he had won a place in the air force at 19.

Colonel Zhai became a fighter pilot and has clocked up some 1,000 hours of flight time in his career. He was chosen in 1996 to begin training for China’s fledgling space programme.

He said of his astronaut training: “”I’ve flown about 1,000 hours and so I’m pretty comfortable doing that. After coming here I had to study every day at my desk like a student preparing for high school exams and what I studied was pretty dry and quite tough. To be honest, at first I didn’t adapt and I had to work until midnight for the first two years.”

China has ambitious plans for space and its programme is an immense source of national pride. The spacewalk, timed just after the close of the Paralympics on September 17 and the Olympics last month, will take place on the crest of a wave of patriotic fervour. China sent an unmanned space ship to orbit the moon last year, the first step in a three-stage lunar exploration project. A manned lunar voyage is planned for some time after 2017.

Times Recommends

• Sarah Brown says 'no thanks' to veal at G8 - twice
• Stockton-on-Tees is obesity capital of Britain
• Stores blame poor sales on Murray factor