After Earth, Mars may be the most well-studied planet in the solar system.
Since 1965, humankind has sent spacecraft after spacecraft to examine our celestial neighbor. The flybys captured the first close-up photographs of the red planet, revealing a rocky, cratered surface. The orbiters found towering volcanoes, dried-up riverbeds, and enormous storms that choked the thin atmosphere with dust. The landers searched for signs of life in the cinnamon-colored soil but found none. The rovers carved tire tracks into the ground and detected organic molecules embedded in 3 billion-year-old rock, a sign that perhaps some beings may have existed long ago.
But even after more than 50 years of research and exploration, our understanding of Mars remains surface-deep. Spacecraft have drilled into the rock and scooped up soil samples, but they haven’t made it very far.
“We know a lot about the surface of Mars, we know a lot about its atmosphere, and even about its ionosphere, but we don’t know very much about what goes on a mile below the surface, much less 2,000 miles below the surface down to the center,” explains Bruce Banerdt, a scientist at NASA’s Jet Propulsion Laboratory who studies the evolution of Mars.
Scientists like Banerdt will soon learn more. A NASA spacecraft unlike any other touched down on Mars on Monday afternoon. In the weeks ahead, a robotic arm will unpack some scientific instruments and place them gently on the ground. The tools will spend their entire lifetimes in these spots, pressing themselves into the surface to probe what’s going on deep below the surface.
For the first time, human begins will be able to study another rocky planet in the same depth as they have their own.
The mission is called the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, which the acronym connoisseurs at NASA have shortened to InSight. InSight has spent the last seven months coasting through space at a cool 6,200 miles an hour, and the last several days preparing for a turbulent descent through the Martian atmosphere. InSight touched down in Elysium Planitia, a flat, smooth plain mostly devoid of rocks and hills, just 373 miles north of its NASA neighbor, the Curiosity rover.