Nasa's first spacecraft built to explore the deep interior of another world streaked toward a landing scheduled for Monday on a vast, barren plain on Mars, carrying instruments to detect planetary heat and seismic rumblings never measured anywhere but Earth. After sailing 301 million miles (548 million km) on a six-month voyage through deep space, the robotic lander InSight was due to touch down on the dusty, rock-strewn surface of the Red Planet at about 8 pm GMT. If all goes according to plan, InSight will hurtle through the top of the thin Martian atmosphere at 12,000 miles per hour (19,310 kilometers per hour). Slowed by friction, deployment of a giant parachute and retro rockets, InSight will descend 77 miles through pink Martian skies to the surface in 6 1/2 minutes, traveling a mere 5 mph (8 kph) by the time it lands. The stationary probe, launched in May from California, will then pause for 16 minutes for the dust to settle, literally, around its landing site, before disc-...