Disease-watching satellites, conceptual image. Satellites collecting data from Earth, which will be used to predict and prevent disease epidemics. The satellites are initially used to build up a climate profile of a region. With the addition of high-resolution imagery and demographic information, changes in a region's conditions that lead to disease can be tracked and potential disease hotspots identified before an outbreak has time to spread. One such disease that is monitored is malaria, a disease spread via infected, blood- sucking mosquitos (centre), which kills at least one million people a year.