Landsat images are the first and foremost inventions of the last 25 years because they help us understand the process and problems of desertification

Remote-sensing systems, land-monitoring networks, and global data bases of field observations are what evidently caused the problem of desertification.

Such global monitoring systems are necessary to better understand desertification because no other system, network or database could be less accurate than Landsat images.

Landsat images may help understand the processes and problems of desertication, but more remote-sensing systems, networks and databases are needed before the matter could be properly and completely understood.