Europa is the sixth moon of Jupiter and has been discovered by Galileo in 1610. It is extremely possible that at that time, life has been swimming around in the subsurface ocean Europa almost certainly contains. For all those 400 years, it’s entirely possible that extraterrestrial life has been around, but we just haven’t known it. This is as intriguing a reason as any to go there right now.
The surface of Europa is the smoothest in the entire Solar System, which supports the concept that there is a water ocean beneath it. There are not many craters but one of note is the Pwyll crater, whose bright white appearance again implies the presence of water below the surface. When it comes closer to Jupiter the gravitational pull is raised, which slightly moves the world out, and once it goes further away in its own orbit, Europa returns to its spherical form. This stretching causes the planet to heat up by friction and is its internal source of heat. This enables liquid water to exist on its surface in such a cold part of the Solar System. It is also an excellent example of gravitational energy turning to kinetic energy, which in turn becomes heat energy.
There have been many probes which have visited Mars in the hope of locating present or past life. Yet Mars is a dry, dusty desert of a world. It’s quite unlikely to harbor any sorts of life now, although its odds of having played host to germs in the past is still quite good. However, there is nothing as convincing as a liquid water ocean to hold extraterrestrial life in the present moment. As you read this guide, weird and amazing creatures could be swimming across the deathly cold oceans of Europa, or parked around some hydrothermal vent (as we see in the ocean depths on our own planet Earth). It’s for this reason that we must go to Europa, not over twenty, not over ten, but as soon as possible. A robotic probe could be transmitted within five decades.
A robotic probe would have to carry substantial power on board, maybe by nuclear fission. It would have to melt through the solid ice crust that’s at least ten kilometres thick, and then release a probe which could swim through the cold oceans and transmit data back to earth.
Unfortunately, a plan known as the Jupiter Icy Moons Orbiter was shelved five years ago, and funding cuts have noticed a string of false starts in the search for life on Europa. If we are to find extraterrestrial life anytime soon, this needs to change.