What Is Mars Made Of?
QUICK ANSWER
Mars has an iron-rich core (likely partially molten), a silicate rocky mantle, and a basalt crust covered in iron-oxide dust. The structure is similar to Earth's, but Mars has a proportionally larger core for its size. NASA's InSight lander mapped Mars's interior by listening to seismic waves from marsquakes.
Mars is built like Earth in basic structure: iron core, rocky mantle, thin crust. The proportions are different, and the way we learned them is more interesting than the layout itself. Mars revealed its interior to a lander that essentially listened for earthquakes.
What are Mars's layers?
Mars has three main layers, similar to Earth's. According to NASA, Mars has a metallic core (mostly iron and nickel with some sulfur), a silicate rock mantle, and a thin crust of basaltic rock and dust. The core is estimated to be about 2,200 miles in diameter, taking up a much larger fraction of Mars's interior proportionally than Earth's core takes up of Earth. The mantle is about 1,000 miles thick, and the crust ranges from about 6 to 30 miles thick.
What is Mars's surface made of?
Mars's surface is dominated by basalt, a dark volcanic rock, covered with a fine layer of iron-oxide dust that gives the planet its red color. The dust contains tiny particles of rust (iron-bearing minerals oxidized over billions of years) along with silica, sulfates, and other minerals. Mars also has frozen water ice mixed into the soil at higher latitudes and at the polar caps. The surface is geologically inactive today, with no plate tectonics and very little active volcanism.
How do we know what's inside Mars?
Mostly through seismology. NASA's InSight lander, which operated on Mars from 2018 to 2022, was equipped with a sensitive seismometer that detected over 1,300 marsquakes during its mission. By analyzing how seismic waves traveled through Mars's interior, scientists were able to calculate the size and density of the core, mantle, and crust. Before InSight, our knowledge of Mars's interior came mainly from gravity measurements and indirect observations. The mission essentially gave us our first inside view of another rocky planet.
Is Mars's core liquid or solid?
At least partly liquid, based on InSight data. Mars's core is thought to contain enough sulfur and other lighter elements to keep it molten at the temperatures and pressures present inside the planet. This was a notable finding because Mars's small size suggests it should have cooled more quickly than Earth. A still-molten core might explain how Mars retained a global magnetic field in the distant past, though the magnetic field has long since shut down. Why it shut down is still being studied.
Mars is built around an iron-rich core, wrapped in a rocky mantle and a thin basalt crust dusted with iron oxide. The structure looks a lot like Earth's, with different proportions. The way we know this comes from listening to marsquakes through a lander, which is one of the more elegant scientific achievements of the past decade.
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