The Search for Life in the Outer Solar System

The Search for Life in the Outer Solar System. From the writer of The Terraformers’ Toolkit. www.amazon.co.uk/dp/B09X6739P...
I have spit this subject into two videos, one about the inner solar system and the second about the outer solar system. This video is about the outer solar system.
Why?
NASA and other space agencies have been searching for life elsewhere in our solar system for over 50 years. The reason is that they would like to know if life on Earth is the only sort of life in our solar system. On Earth all living things use the same DNA and cellular chemistry because they are all descended from the same common ancestor.
If they discovered alien life they would like to know if it’s the same. If it is, then that means life in our solar system has some way of jumping from planet to planet.
If it’s completely different, it means there is a second origin, that it appears frequently and its likely to be common in our galaxy. So we’ll find it everywhere and it’ll be completely different each time.
One added bonus is that if it is very different, then we may be able to use its enzymes, hormones, proteins and other chemicals to help us make food, pharmaceuticals and many other products in the cold of deep space.
In the outer solar system temperatures are considerably lower than on Earth, so if we find life here, it is likely to completely different from life on Earth. The principle indication of a good environment for life is liquid water.
Jupiter’s Moons
Jupiter has four large moons, which are defined as Galilean because they were spotted by Galileo in 1609.
Of these Europa is the most interesting because it has a thick ice crust underlain by a deep liquid water ocean. This is kept liquid by radioactive elements within its core and tidal heating. It’s in contact with this moon’s rocky surface which would provide the chemicals essential for life.
Ganymede, the third of Jupiter’s moons is the largest moon in our solar system, has a weak, magnetic field, and an outer layer of water and ice. It is possible that the lowest layers of this slushy crust may be in contact with the rocky mantle, which would give it the critical chemicals for life.
Calisto is the last of Jupiter’s four Galilean moons where a weak magnetic field has been detected. This may be caused by the presence of an internal ocean with high levels of salinity, but it’s not known if this is in contact with rock or not. If it is, then life may be possible.
Saturn’s Moons
Of Saturn’s moons, Titan is the largest and by far the most interesting. It possesses a thick nitrogen atmosphere, and methane and ethane lakes, seas and rain. It also has a complex mixture of organic molecules produced by dissociation of nitrogen and methane by ultraviolet light.
However, it is extremely cold at -179 C (-290 F), which means that water ice behaves like rock. If life were found on the surface it would be completely different from life on Earth, and would be very uncomfortable at temperatures we find pleasant, so there are unlikely to be any planetary protection issues.
Deep beneath its surface Titan may have a liquid water ocean kept warm by radioactive elements in its core and by some tidal heating.
However, this ocean is probably not in contact with the this moon’s rocky core, though the overlying ice shell is rich in hydrocarbons which might provide some of the chemicals needed for life.
Enceladus
Another of Saturn’s moons, Enceladus, is also ice covered, but it ejects water plumes thousands of kilometres into space from a series of deep crevasses or ‘tiger stripes’. Volatiles and organics in these plumes are believed to be produced by sea floor hydrothermal vents powered by radioactive elements and tidal heating. This means that this moon’s ocean is sandwiched between a rocky floor and a thick ice crust.
Additionally there may be more oceans on other of Saturn's moons, for example Dione and Mimas.
Neptune’s Moons
Next we come to Triton which is Neptune’s largest moon. It has a thin nitrogen atmosphere replenished by cryovolcanoes and may have a sub-ice ocean kept warm by radioactive elements and tidal heating. It is not known if this ocean is in contact with the core or not, so we don’t know if it has the right elements needed by life.
Kuiper Belt
Pluto is the largest object in the Kuiper Belt and is a spherical dwarf planet. It benefits from radioactive elements, tidal heating and remnant impact energy from its formation.
It has a thin nitrogen and methane atmosphere, replenished by cryovolcanoes which imply the presence of syrupy ammonia and liquid water ocean. Whether it is in contact with the rocky core isn’t know.
Summary
Finding other forms of life in our solar system would be change our understanding of our place in the cosmos, and might provide us with a host of new chemistries to help us survive in space.

[@salemsmith2878]

Could life from earth already somehow spread to other parts of our solar system? Like via an asteroid chunk or satellite or something else somehow? I wonder if it might become harder to tell if life has a truly different origin the longer we are around.

[@charlesjoynson7758]

That’s correct Salem. However it would be much harder for an asteroid to get to the outer solar system than the inner. So we far more likely to find earth life on Mars than on the outer solar system moons. Another point is that once it’s actually arrived, either on earth or on Mars, it would start to mutate and would evolve differences, although it would still share DNA with us.