Earth & Titan

NASA JPL scientists look for Earthly examples of the terrain features they’ve been seeing on Saturn’s moon Titan, including the dry landscapes of Death Valley, California. From NASA’s Jet Propulsion Laboratory.

Since we’re probably never going to get to the surface of Titan and be able to pick up the rocks and take samples of the liquid, we wanted to be able to understand a place that we can get to, and then draw conclusions about Titan.

We believe that geology is geology everywhere. So we’ve come to Death Valley, to Racetrack Playa. It’s a dry lake right now, but it’s a lake nonetheless; so we can look for similar pieces of evidence. The reason we do that is we can crawl around Death Valley and measure things. We could find out what’s happening and find out what causes that evidence to occur. And it’s just like a detective game from there on.

So whenever you have a high thing next to a low thing, you can be sure that something’s going to happen. Nature likes to even itself out. On Ontario Lacus, we have high things right next to low things. So the rainfall is going to move the material from the high to the low and it’s going to form these same alluvial fans where material washes out from the gully like it does here, and it’s going to flow the material down to the lakebed.

At Ontario Lacus, there are pieces of bedrock like this, only probably made out of water ice, that make fingers that extend down into the lake. It’s as though the lake had risen up and flooded those valleys. Now this is a much smaller example than we see on Ontario Lacus, but it tells us that the level of the water is what has made this into a finger, not the finger itself.

On Titan, we think that the lakes are filled by seasonal drainages. Sometimes, those drainages make cross-hatch patterns that look like gullies. So we looked on Earth for a place that has those cross-hatch gullies, and here we find it at Racetrack Playa. Water that comes down from those hills flows in infrequent but violent thunderstorms out onto Racetrack Playa. As the rainfall comes down closer to the playa, on Titan, they form deltas, something like the Mississippi Delta out there.

This is a dry lakebed, so what happens is that the gravel just gets pushed out onto the lakebed. And that’s a clue, that what’s happening on Titan is a fluid, not a dry lakebed. So by studying the relationship between the evidence and the events here in Death Valley,where we can measure them, we can connect that same set of evidence to the events that might have happened on Titan.

It’s important because if we’re going to find life somewhere else in the universe, it has to have something in common with the once place that we know has life, and that’s here.

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