Hello everyone!This week on The Cosmic Companion, we will explore The Water Worlds of the Solar System, talking with Olivier Witasse from the European Space Agency, Project Scientist for the Jupiter Icy Moons Explorer, or Juice, now on its way to the Jovian system.Join me, your trusty celestial tour guide, as we don our intellectual swim trunks and dive into the water worlds of our solar system. Water, essential for all life on Earth, was once thought to be rare in the solar system.Large quantities of water ice are now believed to sit inside deep craters at the poles of the Moon, where sunlight never strikes. Ice deposits at the South Pole of the Moon alone could hold more than 150 times as much water as the Mediterranean Sea.These vast deposits of water mean these regions are where the first human settlements on the Moon will soon rise. But native life seems unlikely inside huge blocks of solid ice billions of years old. [<<< Shows what you know. I live in the coolest neighborhood in the solar system!]Mars was, likely, once home to massive oceans. But now, water on this world is thought to be restricted to thimble-sized deposits buried a couple metres beneath its ruddy surface. Although microbial life might exist in these tiny abodes, you really can’t do much chemistry in a thimble.[>>> What is wrong with this guy, seriously? I’ve raised over 674,000 children in this thimble, and they turned out just fine!]Next up is the King of the Planets. Of the 80–95 known moons of Jupiter, three are now believed to house vast oceans of liquid water.Callisto is the most heavily cratered object in our solar system. Once thought to be a dead body, evidence for subsurface oceans was spotted by the Galileo spacecraft in the 1990s. This same craft also found a thin atmosphere of carbon dioxide, similar to the one in Isaac Asimov’s story “The Callistan Menace.” Unlike that story however, giant caterpillars were nowhere to be seen.[___ Dude! I’m right here! Hello! Giant caterpillar!]] {SCRATCH HEAD}Ganymede is larger than the planet Mercury, and it is the only moon known to have its own magnetic field. This behemoth world could also be home to the largest ocean in our family of planets. Bodies of water on Ganymede may stretch 10 times deeper than Earth, buried under 150 kilometers of ice. That’s five times deeper than the average crust of Earth here on Terra Firma. These massive oceans might also be sandwiched between layers of mineral-rich rock, greatly increasing the amount of chemistry happening at the boundaries between water and rock, where life on Earth first took hold.[[VENDOR: Get your Europa sandwich right heah! We got rocks, we got watah! We got little green stuff squirmin’ around dere. And slime! Extra slime! Also, pickles! CUSTOMER: Ewww… Gross! Disgusting! No thanks! Who eats a sandwich with pickles?]]Europa, with an iron core, rocky mantle, and an ocean of salty water… Sound familiar??? [->] …may be the best place in the solar system to search for extraterrestrial life. Oceans here could hold twice as much water as is found on Earth.The surface of this world is covered in water ice, bent and pulled by tidal forces due to gravity from Jupiter. This action breaks the icy surface, and it cracks apart from stress, like every couple by the end of a Paul Simon song. Heat from this process might also help warm the oceans of Europa, increasing hope of extraterrestrial life forming on this distant world. On 14 April, the Jupiter Icy Moons Explorer spacecraft, lovingly known as Juice, lifted off on its way to explore these intriguing moons of Jupiter. Next up, we talk with Olivier Witasse from the European Space Agency, Project Scientist for Juice. — Next up, we head on out to the Ringed Planet. After staring at Saturn’s rings, mouth agape for 22 minutes like James Kirk first seeing the Enterprise in Star Trek: The Motion Picture, we turn our sights to two intriguing worlds — Titan and Enceladus. Titan is best-known for having massive oceans