Jupiter’s moon Europa is almost five times as far away from the sun as Earth is, with surface temperatures that don’t rise above minus 260 degrees Fahrenheit. It’s slightly smaller than our moon and orbits but 400,000 miles from the solar system’s largest planet, which it takes but 3.5 Earth days to orbit. As a result it is tidally locked, always showing the same face to Jupiter.
When it comes to potentially habitable objects in our solar system, Europa would not seem to be a terribly likely possibility.
But, of course, it is. And in three years NASA’s Europa Clipper mission will launch to explore what would appear to be one of the most unlikely yet possible places in our solar system to find potential signs of life.
The reason why is that scientists are almost certain that under Europa ‘s 10-to 15 mile ice covering is a deep, global ocean of salty water.
The size of the ocean has not been well determined yet, with estimates of between 40 and 100 miles of depth. But a consensus has been reached that the ocean is likely to be global, and contains two to three times as much liquid water as found on Earth.
This then raises a question with great significance for Europa, other moons in the solar system and quite likely planets and moons well beyond us: How can there be so much liquid water inside such frigid places?
There are numerous possible answers to that question, and it’s likely that all or most played some role.… Read more