document: Searching for alien life ? Check out failed stars Potential exists on free-floating planets and sub-brown dwarfs , researcher says The search for alien life usually focuses on planets around other stars . But a lesser-known possibility is that life has sprung up on planets that somehow were ejected from their original solar systems and became free-floating in the universe , as well as on small bodies called sub-brown dwarfs , which are stars so small and dim they are not really stars at all , but function more like planets . Studies show these bodies could potentially host atmospheres and surfaces where some form of extraterrestrial life could take hold . Researcher Viorel Badescu of the Polytechnic University of Bucharest in Romania recently investigated the possibilities for life on free-floating planets -LRB- FFPs -RRB- and sub-brown dwarfs -LRB- SBDs -RRB- that might contain lakes of the chemical ethane . He found that such life is not impossible , though it would be significantly different from life on Earth . His findings were detailed in the August 2010 issue of the journal Planetary and Space Science . Failed stars Sub-brown dwarfs are not large enough to generate the nuclear fusion that powers normal stars . Having failed as stars , they slowly radiate their internal thermal energy as heat and very dim light - hence , they are extremely hard to detect . Both free-floating planets and sub-brown dwarfs do n't always orbit around a parent star , and can be found in interstellar space . Lacking a star , life on FFPs and SBDs would have to rely on the body 's internal heat and the decay of radioactive elements for energy . '' `` One may expect a rather stable heat release for long periods of time , exceeding two or three times the present age of the solar system , '' '' said Badescu . Though meager , this heat could be trapped on the object by an optically thick atmosphere . But life needs more than just heat to thrive . Another important ingredient for habitability is a solvent - a liquid environment where important chemical reactions can occur . Life on Earth uses water as a solvent , but that 's not the only option . '' `` Synthesis of observational data makes it possible to conceive chemical reactions that might support life involving non-carbon compounds , occurring in solvents other than water , '' '' Badescu wrote in his paper . In particular , Badescu found that ethane - a compound of carbon and hydrogen - could function well as a solvent for alien life . Life without water It seems odd to consider the possibility of life on an object more massive than Jupiter or Saturn , especially since most scientists think such gas giant planets - with their high radiation , hostile atmospheres and potential lack of a planetary surface - would not harbor life as we know it . But Badescu said that some sub-brown dwarfs might have lakes or oceans of liquid ethane that could prove quite homey to alien microbes . The main difference between water and ethane for use as a solvent is that water is a polar molecule , meaning one end of the molecule is positively charged , and one end of it is negatively charged . This has proven integral to Earth life , because the polar properties of water enable certain kinds of molecules to dissolve easily in water , while others remain stable . NASA / JPL-Caltech In this illustration , twin brown dwarfs orbit each other . Despite the name '' `` brown dwarf , '' '' these objects cool and change over time , and therefore do not have a definitive color . The molecules that code for life - DNA and RNA - have electrical charge properties that allow them to change their internal structure - the specific order of the base molecules within them - and still have the same overall physical properties . This is all enabled by the way their charge properties interact with the polar quality of water . That would not be the case with ethane , which is a non-polar molecule . With DNA and RNA in this situation , '' `` small changes in molecular structure may create large changes in molecular behavior , '' '' Badescu said . '' `` That is not acceptable in an encoding biopolymer that must support Darwinian evolution , in which case , the molecule 's physical properties must remain relatively constant when the informational content changes . '' '' However , the challenge is not insurmountable - a completely different type of molecule could be used to code life 's blueprint on a FFP or SBD . Searching for life Ultimately , free-floating planets and sub-brown dwarfs could prove a fertile place to look for extraterrestrial creatures . Besides their habitable qualities , these bodies seem to be quite common in the universe . Sub-brown dwarfs weighing between 1 and 13 Jupiter masses may be about as common as stars , Badescu said . '' `` The total number of FFPs and SBDs may exceed the number of stars by two orders of magnitude , although most of them should be low-mass rock/ice planetary embryos ejected from planetary systems in formation , '' '' i.e. not the type with large gaseous atmospheres that would retain the heat required for life , Badescu said . '' `` Thus , it might be conceivable that FFPs and SBDs are the most common sites of life in the universe . '' ''
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