Recent space exploration using sophisticated telescopes and space probes has given us a great deal of information about the physical characteristics and prevailing conditions on the planets and moons of the solar system. This information indicates that the appearance, survival and evolution of life in any of those worlds will be very difficult and impossible for advance lifeforms. The discovery of worlds circling other stars different from the Sun has become a major issue in the understanding of possible scenarios where extraterrestrial life can eventually be found. Although we have not found a twin sister of Earth, the incredible number of worlds with unimaginable characteristics and surface conditions has opened the possibilities to new ways of searching for life elsewhere.
Defining the information and blueprints we should look for as indicators of biological activity on those worlds has become a new challenge for scientists.