China opens 2012 with ZiYuan-3 launch via Long March 4B

by Rui C. Barbosa

China launched a new high-resolution remote sensing satellite on Monday at 03:17 UTC using the Long March 4B (Chang Zheng-4B -Y26) launch vehicle from the Taiyuan Satellite Launch Center. According to the official Xinhua News Agency, the ZiYuan-3 its first high-resolution geological mapping satellite, to be used for civil purposes.

Chinese Launch:

The ZiYuan-3 (ZY-3) is the first of a new series of high-resolution civilian remote sensing satellites, grown from a project that was initiated in March 2008.

The new satellite carries three high-resolution panchromatic cameras and an infrared multispectral scanner (IRMSS). The cameras are positioned at the front-facing, ground-facing and rear-facing positions.

Two cameras (front-facing and rear-facing) have a spectral resolution of 3.5m and 52.3km ground swath while the ground-facing camera has a spectral resolution of 2.1m and 51.1km ground swath. The IRMSS has a spectral resolution of 6.0m and 51.0km ground swath.

At launch the satellite had a mass of 2,630 kg. The satellite is equipped with two 3 meters solar arrays for power generation and will orbit a 505.984 km sun-synchronous solar orbit with 97.421 degree inclination. This orbit will have a re-visit cycle of 5 days.

Operational period will be four years with a possible life extension to five years.

The new satellite will conduct surveys on land resources, help with natural disaster-reduction and prevention and lend assistance to farming, water conservation, urban planning and other sectors, surveying the area between 84 degrees north and 84 degrees south latitude.

The ZiYuan program seems to cover different civil and military earth observation as well as remote sensing programs. The ZiYuan-1 program is focused on Earth resources and looks to have two distinct military and civil branches (this one being operated together with Brazil).

The satellites are operated jointly by the Center for Earth Operation and Digital Earth (CEODE) and the Brazilian INPE (Instituto Nacional de Pesquisas Espaciais – National Institute of Space Research).

The ZiYuan-2 program is probably used for aerial surveillance being operated by the People’s Liberation Army (PLA) while the new ZiYuan-3 series will be used for stereo mapping (like the TH-1 TianHui-1 mapping satellite that is operated by the PLA). ZiYuan-3 will be operated by the State Bureau of Surveying and Mapping.

Together with ZY-3, China also launched the VesselSat-2 microsatellite built by LuxSpace Sarl, an affiliate of OHB AG.

Vesselsat-2 weighs 28 kg and will be integrated into ORBCOMM’s Next Generation (OG2) constellation of 18 AIS-enabled satellites after an in-orbit test and checkout phase.

The exclusive rights to use the data of the Automatic Identification System (AIS) payload belong to ORBCOMM Inc., a global supplier of satellite-based communication and data services.

Launch Vehicle:

The first orbital space launch of 2012 was the 156th successful Chinese orbital launch, the 156th successful launch of the Chang Zheng launch vehicle family and the 37th orbital launch from the Taiyuan Satellite Launch Center.
The CZ-4B Chang Zheng-4B launch vehicle.

The feasibility study of the CZ-4 Chang Zheng-4 began in 1982 based on the FB-1 Feng Bao-1 launch vehicle. Engineering development was initiated in the following year. Initially, the Chang Zheng-4 served as a back-up launch vehicle for Chang Zheng-3 to launch China’s communications satellites.

After the successful launch of China’s first DFH-2 communications satellites by Chang Zheng-3, the main mission of the Chang Zheng-4 was shifted to launch sun-synchronous orbit meteorological satellites. In other hand The CZ-4B Chang Zheng-4B launch vehicle was first introduced in May 1999 and also developed by the Shanghai Academy of Space Flight Technology (SAST), based on the CZ-4 Chang Zheng-4.

The rocket is capable of launching a 2,800 kg satellite into low Earth orbit, developing 2,971 kN at launch. With a mass of 249,000 kg, the CZ-4B is 45.80 meters long and has a diameter of 3.35 meters.

SAST began to develop the Chang Zheng-4B in February 1989. Originally it was scheduled to be commissioned in 1997, but the first launch didn’t take place until late 1999. The modifications introduce on the CZ-4B Chang Zheng-4B included a larger satellite fairing and the replacement of the original mechanical-electrical control on the Chang Zheng-4 with an electronic control.

Other modifications were an improved telemetry, tracking, control, and self-destruction systems with smaller size and lighter weight; a revised nuzzle design in the second stage for better high-altitude performance; a propellant management system for the second stage to reduce the spare propellant amount, thus increasing the vehicle’s payload capability and a propellant jettison system on the third-stage.

The Chang Zheng-4B uses UDMH/N2O4 for all three stages. The first stage uses a YF-21B motor consisting of four 75,000kg thrust YF-20B thrust chambers motors with swinging nozzles. The second stage is similar to that of the CZ-3A, with a YF-24F rocket motor consisting of one 75,000kg thrust YF-22B main motor with fixed nozzles, and a YF-23F swivelling venire motor with four chambers motors (4,700kg thrust in total).

The third stage is a specially designed unit powered by a 98kN YF-40 rocket motor.

The Taiyuan Satellite Launch Center:

Situated in the Kelan County on the northwest part of the Shanxi Province, the Taiyuan Satellite Launch Center (TSLC) is also known by the Wuzhai designation. It is used mainly for polar launches (meteorological, Earth resources and scientific satellites).

The center is at a height of 1400-1900m above sea level, and is surrounded by mountains to the east, south and north, with the Yellow River to its west. The annual average temperature is 4-10 C, with maximum of 28 C in summer and minimum of -39 C in winter.

TSLC is suitable for launching a range of satellites, especially for low earth and sun-synchronous orbit missions. The center has state-of-the-art facilities for launch vehicle and spacecraft testing, preparation, launch and in-flight tracking and safety control, as well as for orbit predictions.

The launch center has two launch complexes with a launch pad each (LC7 and LC9), a technical area for rocket and spacecraft preparations, a communications complex, mission command and control complex, and a space tracking complex.

The stages of the launchers are transported by railway, and offloaded at a transit station south of the launch complex. They are then transported by road to the technical area for checkout and testing.

The launchers are assembled at the launch pad using a crane at the top of the umbilical tower to hoist each stage in place. Satellites are airlifted to the Taiyuan Wusu Airport 300 km away, and then transported to the center by road.

(Images via and Xinhua)

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