NASA’s Cassini probe found signatures consistent with microbial life on Titan (one of Saturn’s moon).
The main candidates for life in the solar system have been Mars, Titan and Europa. Triton and Enceladus have a reasonable case for a lot of liquid water. 600 million tons or more of ice water have been found on our own moon, which was previously believed to have no water. The discovery of a lot of water on the moon and its new solar water cycle (solar wind interacts with lunar soil to make thin layer of water.) could mean many more places could have some water which could the molecules of which could make their way to cold traps.
Methane on Mars is part of an increasingly strong case of life on Mars.
Liquid Water Around the Solar System and Probably Life In It
Europa (sixth moon of Jupiter) has perhaps the largest liquid ocean in the solar system.
The liquid ocean has not been absolutely confirmed but the evidence is leaning that way.
Enceladus, sixth moon of Saturn also probably has a liquid ocean.
Enceladus is one of only three outer solar system bodies (along with Jupiter’s moon Io and Neptune’s moon Triton) where active eruptions have been observed. Analysis of the outgassing suggests that it originates from a body of sub-surface liquid water, which along with the unique chemistry found in the plume, has fueled speculations that Enceladus may be important in the study of astrobiology.[ The discovery of the plume has added further weight to the argument that material released from Enceladus is the source of the E ring
* Triton’s density implies it is probably about 30–45% water ice, with the remainder being rocky material.
* Because Triton’s surface indicates a long history of melting, models of its interior posit that Triton is differentiated, like Earth, into a solid core, a mantle and a crust. Water, the most abundant volatile in the Solar System, comprises the moon’s mantle, which lies over a core of rock and metal. There is enough rock in Triton’s interior for solid-state convection to be occurring within its mantle, powered by radioactive decay. The heat may even be sufficient to maintain a “subterranean ocean” similar to that which is hypothesized to exist underneath the surface of Europa. The possible presence of a layer of liquid water suggests the possibility, if unlikely, of life
If Microbial Life and Water Were Widespread, then Panspermia nad Exogenesis …
Panspermia is the hypothesis that “seeds” of life exist already all over the Universe, that life on Earth may have originated through these “seeds”, and that they may deliver or have delivered life to other habitable bodies.
The related but distinct idea of exogenesis (outside origin) is a more limited hypothesis that proposes life on Earth was transferred from elsewhere in the Universe but makes no prediction about how widespread it is.
Other Solar Systems pass within one light year of our solar system about once every million years. We know there is a large comet cloud around our solar system. There could be more frequent exchanges of comets and rocks blasted off of planets and moons that harbor life. Materials with life seem more likely to spread around the galaxy.
We would expect that the lower mass stars move [faster] than the higher mass stars.
More non-standard motion would probably mean more mixing and more closer passes for solar systems.