or, once DID hold water. during formation [let's say], and probably not that long ago in terms of mars-a-logical history
accelerometers read 1G in the direction of gravity (combined sum of all 3 axes on typical 3 axis accel) and so you can use them to determine the orientation of things. Re-purpose to use them to measure gravity differences is pretty smart. I've done coding with the angular position in the past, in that case for a surfboard, and did an interesting "video" of xyz plots to show what was happening over time. I'm guessing they take regular measurements of the IMU, now, and extrapolate the gravity changes from it.
beer icon, of course!
Biting the hand that feeds IT
