Cassini's Altimeter on Titan

Cassini had an altimeter as part of its radar actually and all that does is it sends a radar echo down to the surface, bounces off the surface, and comes back. As it was getting altimetry across the sea, the observation was designed to look for waves on Ligetomari. It didn't see any waves but it did measure the best imagery of the sea and that the radar signal went all the way through the sea, off the sea floor and came back. That's how we measured the depth of the seas, which is amazing. You're going at like multiple kilometers per second and it was kind of an accidental observation and you're using it as the sound