Femto-satellites are satellites with a mass lower than 100 grams. These new categories of satellites are, by concept, low cost devices if they are based on Commercial-of-the-Shelf (COTS) components. Some examples of applications are related to low-cost missions with short time of development. In addition, if they use Low Earth Orbits like 250 kilometers, they use the orbit for few weeks and then the orbit is free to be reused. This new point of view will allow us to design and to use new kind of strategies more dedicated to a particular mission and at the same time adaptive to unpredictable needs like to provide dynamic support for earthquakes. In this paper we present a study of the current sensors like QUICKBIRD, WORLDVIEW and 20 more, very often used in these kind of emergencies, in the direction to, in one hand, to identify which kind of sensors are required for such missions. In the other hand we study the COTS market of sensors that can be installed on-board of a femto-satellite in terms of higher performances, low cost and low consumption. Each sensor selected was validated for space conditions assuming small areas of scanning, short periods of exposure to the outer space environment, high acceleration and high vibrations.