After completing its first full Martian year on the surface of the Red Planet, the scientists for the lander InSight today gave a report [pdf] of their results at this year’s annual 52nd Lunar and Planetary Science Conference, normally held in Texas but being done virtually this year out of terror of the coronavirus.
All told the lander’s seismometer has, as of just a few days ago, detected just over 500 quakes. The map to the right, showing the most distinct quakes and their locations, was adapted from a different presentation [pdf] at the conference. The numbers indicate the sols after landing when these quakes were detected.
This is essentially the region on Mars that I call volcano country. Some of the lava flood plains here are the youngest on Mars. To the east just beyond the edge of the map is the Tharsis Bulge, which holds Olympus Mons and the string of three giant volcanoes to its east. South of Cereberus Fossae but north of the yellow-colored cratered highlands is the vast Medusae Fossae Formation, the largest volcanic ash deposit on Mars.
The quakes suggest they are occurring as large blocks shift along faults, creating fissures and cracks that geologists call grabens. The long fissures of Cereberus Fossae are considered an example of grabens, so this activity suggests that shifting is still going on in the region.
In addition to outlining the location of the detected volcanoes, the presentation today summarized these other discoveries made by InSight about Mars’ interior structure:
- The crust of Mars has likely two or three layers either 12 or 24 miles thick, with a total thickness no more than 45 miles. This is much thinner than most scientists had expected.
- The mantle layer below the crust is estimated at about 250 to 375 miles thick, with a temperature between 1,600 to 1,700 degrees Kelvin. While quite hot, this is a cooler mantle than expected.
- The core of Mars is somewhere between 1,100 to 1,300 miles in diameter, with a outer layer made of liquid. These results are at the high end of pre-mission expectations.
As already admitted, it was noted that the heat sensor experiment will not be able to provide the interior temperature of Mars, as its digging mole was unable to dig into the ground the 9 to 15 feet planned.
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