Nasa announced some ''surprising evidence of activity'' from Jupiter's largest moon yesterday, releasing new images captured from the Hubble Space Telescope. The images provide more evidence that there may be oceans on Europa.However, despite fevered speculation on social media - Europa is considered to be one of the best places to find alien life in the solar system and astrobiologists have theorised that organisms could survive in its oceans - Nasa quelled expectations before the press conference."Astronomers will present results from a unique Europa-observing campaign that resulted in surprising evidence of activity that may be related to the presence of a subsurface ocean on Europa," the agency said.Participants in the teleconference included Paul Hertz, director of Nasa's Astrophysics Division; William Sparks of the Space Telescope Science Institute in Baltimore; Britney Schmidt of the Georgia Institute of Technology; and Jennifer Wiseman, senior Hubble project scientist at Nasa's Goddard Space Flight Centre.Europa one of the largest of Jupiter's 67 known moons. In late 2013 the Hubble telescope observed water vapour erupting from Europa, in what was hailed as a "tremendously exciting" discovery.Previous scientific findings had already pointed to the existence of an ocean located under Europa's icy crust, but it was thought teams in the future would have to drill through the thick later of ice before any signs of life would be detectable. ..