How Cassini's sleuthing revealed an active ocean world.


In February 2005, we had our first close fly-by of Enceladus, and the magnetometer signal saw something unusual.

What a magnetometer does is it measures the magnetic field in the vicinity of the instrument. We had a look at the wiggles, and they looked strange. The magnetic field of Saturn is moving towards it, and it couldn't penetrate down onto the surface, which was pointing to an atmospheric signature of some kind.

Here it looked like it had a tiny atmosphere.

Then in March, we came even closer looking for that same strange signal.

What it showed was that the signature, the atmospheric signature that we were seeing was focused at the south pole. It was almost like there was a cometary plume of water vapor coming off from the south pole.

People were saying, "It's got to be jets! It's got to be jets!" Then the imaging team was saying, "No, we don't want to say that you know until we're sure." So, we went closer. We came within 175 kilometers of Enceladus.

Then we got the data back, and it was spectacular.

And then we found the evidence. Geysers coming out of the south pole with water vapor and water ice particles. They were active geysers at the south pole of Enceladus.

Because we were so close all of the other instruments were able to take really good data and we put together all of this data and we saw the cracks, the tiger stripes at the south pole. We saw heat leaking out from these tiger stripes. On subsequent fly-bys we found organic material, dust, water vapor coming out of the plume.

The Cassini discoveries in the first three flybys were so amazing. We changed our focus and added 20 more flybys of Enceladus, including seven through the icy jets.

The surprising magnetometer reading led us to the liquid water ocean underneath Enceladus's icy crust.


After over a decade of research with Cassini, we now know there's a potential for the ocean on Enceladus to support life, and that has altered the way we think about where life might be found in our own solar system, and in the worlds beyond.

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