"As seismic waves travel through [Mars] they pick up information along the way; as they travel through different rocks," explained Dr Bruce Banerdt, InSight's principal investigator. "We don't think that plate tectonics is active on Mars but we fundamentally don't know at the moment, and so just seeing the pattern of seismicity that comes in - that's going to be just a critical bit of information in and of itself." "If you take a raw egg and a cooked egg and you spin them, they wobble differently because of the distribution of liquid in the interior," explained InSight's deputy project scientist, Dr Suzanne Smrekar. "So by tracking our spacecraft very precisely, we're able to see how Mars wobbles and that really tells us a lot of information about the core of Mars."