Welcome back to our journey for life in the Solar System! Last time we explored the worlds of Mars and Europa for the possibility of life. Now, as promised, we will touch down on four special moons: Ganymede, Callisto, Enceladus, and Titan.  

Ganymede and Callisto 

We begin with Ganymede and Callisto, which, like Europa, are two other moons of Jupiter which may have giant saltwater oceans beneath their surfaces. Could there be life lurking in these oceans? In 2022, the European Space Agency, or ESA, plans to send a spacecraft to orbit Jupiter and collect more data from these two moons. While the spacecraft won’t go on to the surface of these planets, it will collect valuable data that would allow for future missions to do so. 

Enceladus 

Now that we’re past the wild moons of Jupiter, we’ve reached an even crazier world: Enceladus, the sixth largest moon of Saturn.  Like Europa, Ganymede, and Callisto, there is also evidence that Enceladus has a saltwater ocean under its surface. In 2005 the NASA spacecraft Cassini detected massive plumes of water shooting out of Enceladus’ surface over one thousand miles an hour! While there are no official missions announced for Enceladus, there most likely will be some in the future. 

Titan 

Last, but certainly not least, is Titan, the largest moon of Saturn and second largest moon in the solar system. Titan is an extremely fascinating world - it has clouds, rain, rivers, lakes, and oceans like Earth, along with its own atmosphere. But it doesn’t rain water on Titan... The rivers, lakes, and oceans here are made of liquid ethane and methane, two chemicals that don't support any life on Earth. However, if there was life on the surface of Titan, it could be adapted to live in these ethane and methane oceans. Another awesome fact about Titan is it may also have an ocean of liquid water beneath its surface. It would be more likely that life exists here. What’s exciting is that NASA has officially announced a mission to Titan. In 2026, they will send the Dragonfly, a drone like spacecraft that will scan Titan’s surface for signs of life. Because Titan is so far away, the Dragonfly will take eight years to arrive! But it will definitely be worth the wait. 

That concludes our voyage of the Solar System. Even though no extraterrestrial life has been discovered anywhere in the universe, that doesn’t mean we won’t find any in the future. Fifty years ago, many of the things we have today - smartphones that allow us to talk to people across the globe, robots that do surgery, and countless other scientific advancements - would have been unimaginable. In the same way, fifty years into the future, we will certainly discover and invent things that we could have never thought of. The future holds so many exciting moments and things we cannot predict. Perhaps, in your lifetime, scientists one day will announce the existence of other life - and that day, the world will be forever changed...