According to a dispatch from the official Xinhua News Agency, the Shanghai Academy of Spaceflight Technology (SAST) held a welcoming ceremony last Friday (Sept. 8) for the "triumphant" return of the launch team.

SAST develops and manufactures the three-stage LM-4 launcher. LM-4B is an upgraded version of LM-4A. The China Great Wall Industry Corporation, which markets the launching service of the LM series of rockets, states that a LM-4 is capable of launching payload of 1,650kg to a 600-km sun-synchronous orbit and 4,680kg to a 200-km circular orbit.

On Sept. 1 the LM-4B rocket lifted off from TSLC and delivered the Ziyuan-2 remote sensing satellite into its planned orbit.

Xinhua reported that the launcher accurately placed ZY-2 into the predetermined orbit. "Deviation of the actual orbital parameters from the predicted values for the semi-major axis, eccentricity and inclination are exceedingly small. This demonstrates the accuracy in inserting the satellite into orbit."

This was the third successful launch of LM-4B in three missions, all of them still considered as test flights of the rocket. SAST technicians who worked on preparing the LM-4B flights had been instructed to achieve the objective of a "safe rollout, on-time launch and complete success".

On May 10, 1999, LM-4B made its debut with a successful launch of the Fengyun-1C meteorological satellite and Shijian-5 microgravity fluid physics and space physics satellite.

Five months later on October 14 a second LM-4B successfully launched ZY-1, also called China-Brazil Earth Resources Satellite (CBERS-1), and Brazil's Satellite Cientifico (SACI 1).

The successful orbit insertion of the two satellites on the October flight was marred by the explosion of the LM-4B third stage in space. The upper stage disintegrated on March 11 this year into more than 300 fragments that were large enough to be tracked by the U.S. Space Surveillance Network (SSN) of the U.S. Space Command (USSC). This is the most significant satellite breakup in nearly four years, according to the Orbital Debris Research division at NASA Johnson Space Center.

Two weeks later the space dust instrument SPADUS aboard the unclassified U.S. Air Force satellite ARGOS (Advanced Research and Global Observation Satellite) detected much finer debris in the form of dust clouds. The breakup of the upper stage is suspected to be caused by fragmentation of the residual hypergolic propellants.

The recent launch of ZY-2 is drawing the attention of Taiwan, which has expressed concern in potential military application of the satellite. Taiwan Defense Minister Wu Shih-wen said soon after the launch that the Taiwan Defense Department would monitor the mission closely.

USSC is also watching the latest firing of LM-4B with special interest, in particular whether China has implemented measures to ensure the integrity of the rocket's third stage which is left in space in an orbit only 5 km lower than ZY-2.

Meanwhile China is still keeping a tight lip on details of the ZY-2 mission. The respected website Go Taikonauts! quoted information posted on the official Chinese website SpaceChina that the Chinese Academy of Space Technology (CAST) designed and built the satellite. The entirely domestically built satellite, which is more advanced than ZY-1, incorporates a standardized sun-synchronous satellite bus. The life expectancy of ZY-2 is two years.

Information obtained from the Orbital Information Group (OIG) at NASA Goddard Space Flight Center indicates that ZY-2 is orbiting the globe once every 94.3 minutes in an orbit of 493 x 474 km. This is clearly lower than the orbit of ZY-1. Compared to the orbital altitude of ZY-1 at 775 x 773 km, the orbit of ZY-2 is nearly 40 percent lower.

Since ZY-2 circles the Earth at a lower altitude, its camera may be able to resolve finer details of objects on the ground. Taiwan's concern is therefore not without merit.

One of the sensors on the 1,540-kg ZY-1 is the High Resolution CCD Camera which has a resolution of 20 meters in the visible spectrum. The camera can point up to 32 degrees to either side of vertical, thus it can image the surface stereoscopically.

It is possible that the LM-4B launcher delivered a heavier ZY-2 spacecraft into a lower orbit so that the camera, possibly an improved version, can see more details. This fuels the speculation that ZY-2 imagery may have military reconnaissance value.

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