Simple life forms in the Solar System
The investigation for life in the Solar System has not always been at the forefront of space programs, but it has been present in the objectives of space agencies around the world. The Viking program in the 1970s, for example, was the first to have the search for life on Mars as one of its primary scientific objectives. Although it didn't find any clear evidence of life, discoveries since then have suggested that life might have developed in the past.
With the recent discovery of briny water seasonally flowing on the Red Planet, and the confirmation of dynamic oceans under the surface of Europa and Enceladus, the attention is shifting to more life-focused exploration. ExoMars, the joint European-Russian Mars program due to launch in 2018, will have the specific intention of detecting biosignatures in the atmosphere and ground of Mars. For other missions, such as those to the oceans of Europa, we will have to wait, although NASA is planning to study Jupiter's moon in more detail soon with a new spacecraft. The technology necessary for an autonomous drilling probe capable of penetrating the icy crust of Europa or Enceladus, though, is still beyond our current capabilities.
A realistic color Galileo mosaic of Europa. NASA/JPL/SETI Institute.