Mars: We just got our best-ever look at the inside of Mars
NASA‘s InSight robotic lander just gave us our first glimpse into the depths of a planet other than Earth.
More than two years after its launch, seismic data collected by InSight has given researchers clues to the formation of Mars, how it evolved over 4.6 billion years and how it was different from Earth. A set of three new studies, published in Science this week, suggest that Mars has a thicker crust than expected, as well as a larger molten liquid core than we thought.
In the early days of the solar system, Mars and Earth were roughly similar, each with an ocean blanket covering the surface. But over the next 4 billion years, Earth became temperate and perfect for life, while Mars lost its atmosphere and water and became the barren wasteland we know today. Learning more about what Mars looks like inside could help us understand why the two planets had such different fates.
“Going from [a] cartoon understanding of what the interior of Mars looks like to put real numbers in it, “said Mark Panning, project scientist for the InSight mission, at a NASA press conference,” we are in able to really expand the family tree to understand how these rocks the planets are formed and how they are similar and how they are different.
Since InSight landed on Mars in 2018, its seismometer, which sits on the planet’s surface, has detected more than a thousand distinct earthquakes. Most are so small that they would be imperceptible to a person standing on the surface of Mars. But a few were important enough to help the team get a first glimpse of what’s going on below.
Earthquakes on Mars create seismic waves that the seismometer detects. The researchers created a 3D map of Mars using data from two different types of seismic waves: shear and pressure waves. Shear waves, which can only pass through solids, are reflected off the surface of the planet.
Pressure waves are faster and can pass through solids, liquids and gases. Measuring the differences between when these waves arrived allowed researchers to locate earthquakes and gave clues to the makeup of the interior.
A team, led by Simon Stähler, a seismologist at ETH Zurich, used data generated by 11 larger earthquakes to study the core of the planet. From the way the seismic waves reflected off the core, they concluded that it was made from liquid nickel-iron and was much larger than previously estimated (between 2,230 and 2,320 miles wide) and probably less dense.