I’m first and foremost a marine scientist, but I’m going to admit something to you all–I’ve kind of got a thing going on the side with astronomy. I’ve been furtively watching the revamped Cosmos (Haven’t seen the show yet? Screw reading this post–head over here and watch it!) and reading about new Big Bang breakthroughs when I should be culturing my diatoms. Now, this doesn’t mean that I love my plankton any less–it’s just that I’m not a one-scientific field kind of girl, you know? There are too many fascinating scientific discoveries happening for me to go steady with one discipline.
It therefore works out well for my double life that this week, I get to combine my two loves in a blog post dealing with…space oceans! (Bet you didn’t see that one coming, did you?) We’ve guessed for a decade or so that the moon Titan, which orbits Saturn and is the second-largest moon in our solar system, likely harbors seas of liquid methane on its surface. Not something you’d want to take a dip in, but pretty amazing considering that its average surface temperature is a chilly -180 degrees Celsius (-292 degrees Fahrenheit). Since we first postulated that Titan might have seas of its own, scientists have been exploring the planet with the aid of unmanned spacecraft in hopes of uncovering its secrets.
You can think of Titan as a sort of warped mirror of Earth–we’ve discovered that it has an atmosphere, seasons, mountains, clouds, and even rain. However, all these processes are dominated not by water, as is the case on Earth, but by hydrocarbons such as methane (which is found on Earth as well, but in much smaller quantities). Instead of studying the water cycle in science class, students on Titan would need to study the methane cycle–although I feel like if I was a student there, I’d be too busy trying not to freeze my pants off to care about the minutia of geochemical cycling.
Despite all these similarities, until now researchers have been unable to find evidence for waves in Titan’s seas. This has puzzled scientists, since Titan seems to have all the necessary ingredients for waves–starting with good, strong winds. On Earth, wind speed, direction, and duration produce the waves we take for granted (or curse, when they cause us to puke over the side of a boat) on the ocean’s surface. These waves mix up the top part of the ocean, helping life to flourish and playing a integral role in the movement of nutrients through the water column. On Titan, some scientists thought that we weren’t seeing waves because the sea’s surface might be frozen or covered with a tar-like substance–but photographs from NASA’s Cassini spacecraft, which flew past Titan in 2012 and 2013, show glints of sunlight reflecting off of the sea’s surface. Although the researchers presenting these new findings calculated the waves that created these glints to be only 2 centimeters tall, they are hoping to see evidence for larger waves as Titan’s seasons change and its winds pick up.
People have proposed that we send unmanned missions to other moons with evidence of liquid water, such as Europa, in order to explore the possibility of extraterrestrial life in these seas. It is unknown if Titan, with its methane-based climate, might be thought of in this same light. Regardless, I can dream of a future generation of oceanographers who study not only our familiar blue and sunlit oceans, but also extraterrestrial seas. Imagine waking up, shrugging into your spacesuit, and stepping outside–starting your day by to sampling one of Titan’s lesser-known hydrocarbon seas for novel chemical compounds. Or perhaps you’d rather jet over to Europa for a submarine dive into its deep, hidden ocean. We’re trained as oceanographers to look downwards, into our own waters, but I think there’s much to be gained from casting our gazes upwards. Titan is telling us–oceanography might not be limited to Earth for much longer.