Satellites face three difficulties

First, search work requires the satellites to operate in the assigned area immediately. But the satellite has a planned orbit and a civilian satellite carries finite fuel with which to maintain its orbital altitude, if the satellite operates a wide-range orbit transfer, it will certainly affect its travel time; so it has low mobility and cannot provide updated images quickly.

Second, the satellite requires high resolution to target objects. But civil satellites might have difficulty finding debris. For example, Chin's highest resolution civil satellite Gaofen-1 is equipped with a 2 meter resolution camera; it means that a 2-meter-long object will appear on Gaofen-1's image as a dot. So this satellite can only distinguish large components of the plane such as body or wings, but it cannot help in finding small targets such as cabin doors, lifejackets, passengers, or other small objects.

Third, the techniques of image interpretation must improve. America's best spy satellite can distinguish an object as small as a 0.1 meter in size, and some of its civil satellites can achieve 0.4 meters. Since floating debris may be of any size , there is no recommended recognition software to spot them. Moreover, ocean waves could make precise detection difficult.

The article is edited and translated from 《多国卫星为何搜不到马航客机 中国卫星还不够好》, source: People's Daily Online and Global Times , author: Zhang Yichi, Liu Yang