We still don't have a clear proof of life outside of Earth, but there are several intriguing possibilities for primitive life to find a haven outside our solar system. Some of Jupiter's and Saturn's moons are fascinating, and there's even the possibility of some surprises on Mars.
For those looking for extraterrestrial life, Mars is a recurrent favorite. The dark stripes that develop in Horowitz crater during the Martian summer are very intriguing. These are most likely salty meltwater, which is only a few inches beneath Mars' dusty skin. This muddy environment could be sampled with a simple probe.
Titan is Saturn's biggest moon and the only place in the solar system known to have liquid lakes (apart from Earth). These are ethane and methane lakes - liquid natural gas - that are constantly replenished by hydrocarbon rain.
Despite the abnormal elements and Titan's frigid temperatures, it is a world in which chemistry thrives.
Strange twin ridges on Jupiter's ice moon Europa's surface could indicate shallow water reservoirs.
An examination of a comparable phenomenon on the Greenland ice sheet reveals that these ridges can be generated on Earth by pockets of liquid water trapped within the ice.
In its faraway home orbiting the Solar System's largest planet, Europa is filled with mysteries. Evidence implies the icy body isn't frozen, and that behind its thick ice shell is a liquid, briny ocean warmed by internal geological processes.
Not only will it be difficult to get a probe behind this icy shield, but Europa's waters are as dark as a cave, making photosynthesis impossible. Something down there, on the other hand, could be surviving on geothermal heat or complicated chemicals from the surface.
Europa's surface is a massive expanse of aqueous ice. Many scientists believe that beneath the frozen top lies a layer of liquid water - a global ocean - that is kept from freezing by flexing heat and might be over 60 miles (100 kilometers) deep.
Geysers erupting through fissures in the surface ice, a weak magnetosphere, and a disordered landscape on the surface, that could have been damaged by ocean currents flowing beneath, are all signs of this ocean. The deep ocean is protected by this frozen shield
This may have ramifications for the search for life on Europa, but we won't know for sure until alarm spacecraft can take measurements from Europa's orbit and compare them to Greenland radar data. Fortunately, ESA's JUICE and NASA's Europa Clipper, both carrying ice-penetrating radar, are set to launch soon to explore the moon.
