Mars lander spies the planet's deep boundaries
Two years ago, NASA's InSight spacecraft alighted on the surface of Mars, aiming to glean clues to the planet's interior from the shaking of distant earthquakes and deep heat leaking from its soil. Mars, it turned out, had other ideas. Its sticky soil has thwarted InSight's heat probe, and in recent months howling winds have deafened its sensitive seismometers. Most mysteriously, the planet hasn't been rattled by…