XI CHANG

For its communications satellite program (Chapter 4), China sought a launch site as close to the equator as possible. Eighty sites were surveyed in 1972, shortlisted to 16 before Xi Chang in Sichuan was selected, apparently by Zhou Enlai personally. Defense concerns were uppermost, the benefits of being far inland outweighing considerations of difficult terrain, poor communications, and a dense rural population. Xi Chang was constructed in the course of 1978-82. The first launch rehearsal was conducted in 1983, with the center opening in January 1984. When it began to fly foreign communications satellites, Xi Chang was opened to visitors and, in the commercial spirit of modern China, tickets to see Moon missions were sold on the open market. It is the home of the Long March 3.

Xi Chang is located 1,826 m up in mist-shrouded mountains. It must be one of the most scenic launch sites in the world. Nearby are rice paddies and grazing buffalo. To the north lie mountains and giant panda reserves and to the south lie lakes. The skies fill from time to time with migrating birds. The launch site is near Xi Chang city and 270 km from Chengdu by rail and road. Xi Chang is on the old south-western Silk Road which started at Chengdu and headed through Xi Chang into Burma (250 km distant) and India. The average temperature is a pleasant 17°C, with 320 days of sunshine a year. The only problem time is mid-summer, when there is often heavy rain and, at worst, the danger of flooding.

To reach Xi Chang launch site by land, one follows the Kunming-Chengdu railway northward along the valley floor of the Anning River until a single branch line turns west into the launch site valley. Visitors arriving there drive along roads cluttered by bicycles, water buffalo, and farm workers carrying chicken and vegetables to market. One then passes a communication center, technical center, and command and control center. To the right of the railway is the first launch pad, used for the Long March 3, served by a large 900-tonne 77-m-tall gantry which has 11 work levels and a crane. A cement flame trench was constructed to take away the flames of the rocket on take-off. An air-conditioned clean room on the top floor protects satellites from dust and humidity. The pad may not appear to have been used since the CZ-3’s last flight in 2000. To the left of the railway, 1,000 m away, is a second launch pad, constructed subsequently for the Long March 2E, ЗА, and 3B. It was built in the course of 14 months and first used for the CZ-2E Badr/Kuafu launch in 1990. This second pad has a huge 4,580-tonne service tower, 97 m tall, with 17 work levels. Just 80 min before launch, the tower moves back to a distance of 130 m. A third pad was completed in 2006 and first used on the Beidou launch of 13th April 2007. Observation platforms with seats for 2,500 places were constructed on the nearby hillsides, with tourists invited to pay ¥800 to watch launches.

Also to the left of the railway line lie buildings for storing launchers, the various stages, and payloads, though they are finally assembled vertically on the pad by crane. The launch towers are protected by 100-m-high lightning rods. Around the gantries are fuelling lines – one set to keep the liquid-hydrogen third stage topped up; a second to provide helium which pressurizes the fuel tanks; another for storable fuels. Liquid hydrogen is topped up in the third stage until just 3 min before lift-off.

Launches out of Xi Chang take a curving trajectory to the south-east, flying over southern Taiwan, the PhiUppines, and towards the equator. The ascent is tracked from either side by ground stations from Yibin and Guiyang, Nanning. Satellites are still just over China when they reach the edge of space.

The countdown is carried out in a blockhouse close to the pad, but the overall operation and the subsequent flight are monitored from the launch control center 6,000 m from the launch pad in a deep gully. The launch control center comprises a large gymnasium-sized room with walls of consoles and a large 4 x 5.3-m visual display at the front. There is an observation room, able to take 500 people at a time. Laser theodolites, set in domes, track rockets as they ascend to orbit.

In more detail, the launch pad and control center. Courtesy: Mark Wade.

A launch campaign in Xi Chang takes 40 days. The rocket is first delivered by rail into a transit hall measuring 30.5 x 14 m, before being brought into a much larger assembly room of 91.5 x 27.5 m. Payloads are checked out in a clean room measuring 42 x 18 m called the non-hazardous operations building where temperatures and humidity are kept within tight limits. The stages and payloads are then transferred to the hazardous operations and fuelling building where fuelled sohd-rocket stages and satellites are installed. Final checks take place in a last checkout and preparation building. The site also has an x-ray facility to check any equipment against cracks. The rocket stages are trolleyed to the pad, one by one, before being assembled vertically.