In the hunt for exoplanets, one of the things astronomers have been desperately searching for is another planet like Earth that is capable of supporting life. Astronomers have found planets in other solar systems in the habitable zone, in orbit where temperatures would be beneficial for life. But so far, they have not found an Earth sized planet in the habitable zone of another star. In recent years, there has been much discussion in astronomy circles over the search for extraterrestrial life, so much that a new name had been accustomed for this study: astrobiology. These studies also focus on planetary habitability, the measure of a planet's or natural satellite's potential to develop and sustain life. Astrobiologists study bulk composition, orbital properties, atmosphere, and potential chemical interactions.
According to some new astrobiological research, planet Earth will not be habitable for much longer. As the sun gets older, it will get larger and warmer, eventually leading to the Earth becoming uninhabitable, first to humans and other complex life, and then, in around 2.56 billion years, to all cellular life. Due to anthropogenic climate change, and other variable factors, it is unsure exactly when human life will cease to exist on planet Earth. After completing a 200 million dollar study, NASA reported that a colony could be dug several feet below the moon's surface to protect residents from high energy cosmic radiation, which can damage DNA and cause cancer. The study envisions an onsite nuclear power plant, solar panel arrays, and methods for extracting carbon, silicon, aluminum, and other useful materials from the lunar surface. Another solution is a sort of "generation ship," for generations living aboard an enclosed ship, they could either remain in Earth's orbit or travel for hundreds of years towards a habitable exoplanet. They may simply float through space, harvesting materials from asteroids and comets along the way.