 With the onset of the Space Age, planetary probes cast increasing doubt on the likelihood of extraterrestrial life in the Solar System, at least life of any magnitude greater than organisms such as bacteria.By the mid-1960s, it was firmly established that life could have no foothold on the hostile surfaces of Mercury or Venus, and that Mars could hardly support any macroscopic life forms on its surface, much less an advanced civilization.In the 1980s it was shown that the surfaces of Jupiter's moons were just as hostile to life.