If there is no major problem, Chinese people will have their long-cherished moon dream realized in 2007, said Luan Enjie, chief commander of China's lunar orbiting program on August 15. Luan said, before that, three technological obstacles need to be conquered.

First, orbits designing. Since the program involves the earth, the moon and the satellite, the designing for the orbit of the moon-probe satellite is more complicated than that for the relative movement of earth and satellite. Luan said, deep space exploration is characterized by the limited "launch window" (a term used to describe a time period in which a particular mission must be launched). The moon, the earth and the launching complex are all moving so a proper position for all of them is needed, but the period for timing is rather short.

Second, the tracking system. The most difficult test for lunar probe is on the tracking system, whose transmission should be able to reach far enough. Currently the longest distance China's satellites ever reached on geosynchronous orbit is about 40, 000 kilometers. But the moon is about 400, 000 kilometers from the earth. This brings a challenge to the transmission capability of the tracking system. "During the lunar exploration, we should be able to hear and see what's going on with the probe, and the moon orbiter Chang'e-I should also be able to hear us. This is also a challenge to China's deep space tracking technology," said Luan.

Third, environment. Luan said, the moon probe is made on the earth, but the temperature difference is 300 degree. It must be guaranteed that the materials, equipment and machinery work well under such a condition. This is a test for China's aerospace technology, the designing capability of technicians as well as the comprehensive ability of China in space activities.

Sources say, these difficulties are as well the areas of innovation. Expert says, the scientific and technological questions mentioned above must be solved for the program to succeed. However, since they involve the forefront areas, if China solves them, it will achieve a leap forward, which will be a strong driving-force for the country's scientific and technological development.

Source: Xinhua