<P> Europa Orbiter--Its objective would be to characterize the extent of the ocean and its relation to the deeper interior . Instrument payload could include a radio subsystem, laser altimeter, magnetometer, Langmuir probe, and a mapping camera . The Europa Orbiter received a go - ahead in 1999 but was canceled in 2002 . This orbiter featured a special ice - penetrating radar that would allow it to scan below the surface . </P> <P> More ambitious ideas have been put forward including an impactor in combination with a thermal drill to search for biosignatures that might be frozen in the shallow subsurface . </P> <P> Another proposal put forward in 2001 calls for a large nuclear - powered "melt probe" (cryobot) that would melt through the ice until it reached an ocean below . Once it reached the water, it would deploy an autonomous underwater vehicle (hydrobot) that would gather information and send it back to Earth . Both the cryobot and the hydrobot would have to undergo some form of extreme sterilization to prevent detection of Earth organisms instead of native life and to prevent contamination of the subsurface ocean . This suggested approach has not yet reached a formal conceptual planning stage . </P> <P> So far, there is no evidence that life exists on Europa, but Europa has emerged as one of the most likely locations in the Solar System for potential habitability . Life could exist in its under - ice ocean, perhaps in an environment similar to Earth's deep - ocean hydrothermal vents . Even if Europa lacks volcanic hydrothermal activity, a 2016 NASA study found that Earth - like levels of hydrogen and oxygen could be produced through processes related to serpentinization and ice - derived oxidants, which do not directly involve volcanism . In 2015, scientists announced that salt from a subsurface ocean may likely be coating some geological features on Europa, suggesting that the ocean is interacting with the seafloor . This may be important in determining if Europa could be habitable . The likely presence of liquid water in contact with Europa's rocky mantle has spurred calls to send a probe there . </P>

At the source of life the full moon