Despite a concerted and dedicated program of Mars exploration by NASA, ESA, and several other national space agencies since the 1960s, a prominent gap in our basic understanding of the planet has persisted for over 50 years: namely, precise information on the fundamental internal structure of the planet. In order to fill this gap, InSight was proposed in 2010 to achieve six specific primary scientific objectives: to determine 1) the thickness of the crust; 2) the existence of any large-scale layering in the crust; 3) the structure of the upper mantle; 4) whether the core is liquid or solid; 5) the size of the core; and 6) the density of the core.
At the time of this writing, the InSight lander has spent nearly three (Earth) years on the surface of Mars. We can now report that the mission has successfully fulfilled all of its objectives. Through a combination of careful seismic analysis of marsquake signals and precision tracking of nutations in Mars’ rotation, we can now place meaningful bounds on all these quantities. In this presentation I will describe these groundbreaking results, as well as some of the other discoveries that have been made on Mars through analysis of the data produced by InSight’s suite of geophysical, meteorological and imaging instruments.