We’ve got bitter cold weather on the way here in Duluth, Minn. with highs predicted around -7 F (-21 C) and lows at night of -20 F (-29 C). What better time to drop in on an even colder place, Saturn’s largest moon Titan. There the average daily high is 290 below zero (-179 C). In those frigid conditions, gases like ethane and methane, of which this moon has an abundance, rain down from the clouds and pool into hundreds of lakes, rivers and seas. From an orbiting satellite, you’d think you were looking at an aerial view of northern Minnesota.
With a surface pressure 1.6 times greater than Earth, Titan’s atmosphere is thick enough to allow liquid hydrocarbons to exist on its surface. It’s the only known body aside from Earth with great quantities of exposed fluids. As for water ice, yes, Titan has that too, but it’s as hard as rock in such a brutal environment.
A new paper by scientists on NASA’s Cassini mission finds that blocks of hydrocarbon ice might dot the moon’s lakes and seas. Their presence is inferred by mixed readings of the lakes’ reflectivity. This is an interesting premise since solid methane ice is denser than the liquid variety and would be expected to sink. But scientists discovered that methane ice will float if the temperature is below the freezing point of methane (-297 F) and the ice contains at least 5% air absorbed from Titan’s atmosphere. Click HERE to read more on the topic.
Titan descent video. At the end at touchdown, you’ll see the shadow of the parachute – amazing!
Eight years ago this week, the European Space Agency’s battery-powered Huygens (HOI-gens) probe entered Titan’s atmosphere after departing the Cassini “mother ship” 3 weeks prior. Huygen ejected its back shell and heat shield and floated down by parachute through the moon’s orange haze. Two and a half hours later it made a slippery-slidey touchdown on the surface. Scientists had hoped it would land in an ocean, since it was made to float, but instead the probe struck terra firma (Titania firma?).
On the way down, Huygens transmitted pictures of its descent as well as photos from the surface. Networks of streams were seen from the air; on the ground, eerie ice boulders are visible near to far under an orange sky. If there were ever a place you’d call alien, Titan would be it.
I expect once the cold sets in, all the extra clothing we vulnerable humans will don will give the place a similar otherworldly look. Cold weather and plenty of atmosphere – two things Titan and Duluth have in common. Maybe we should consider starting a “sister planet” program.
Here are a couple more videos of Huygens’ descent to Titan including one where you can heard winds buffeting the probe and another showing a brand new animation re-creating the craft’s final descent and peculiar landing. Enjoy!
Simulation of how the probe landed based on data sent back by Huygens.
The winds of Titan – listen to the sound