Marsquakes recorded by NASA InSight mission offering the first direct evidence of important boundaries in the Martian interior, which could help planetary scientists understand how rocky planets are formed, suggests a new study.
The spaceship arrived in November 2018 at Elysium Planitia on a quest for the poorly understood interior of Mars. The thickness of the Red Planet crust and the depth of its core, for example, were only estimated earlier with models. InSight lets researchers check their models for the first time.
InSight examines the Martian interior with its seismometer, which lies directly on the ground, and overcomes a problem that a similar instrument encountered on Viking 2 in the 1970s; that was seismometer high on the spaceship and swayed in the wind. (Viking 1 seismometer failed before he could take measurements, according to NASA.)
Related: InSight Mars lander takes dusty selfie on Red Planet (photo)
InSight measured more than 170 trembles between February and September 2019, marking the first definitive seismic measurements taken on Mars. InSight remains active today and more measurements will be integrated into future studies.
The InSight seismometer measures vibrations of seismic waves, which arise from the source of disturbances such as marsquakes as meteor strikes. The shape and strength of the waves scientists can also estimate the composition of the interior of the Red Planet, especially since these waves change slightly as they move through different rock types.
However, there are unique challenges associated with having only the only seismometer active on Mars, compared to the networks of such instruments on Earth. “Mars is much less tectonically active, which means it will have far fewer marsquake events compared to Earth,” lead author Sizhuang Deng, a geophysicist Ph.D. candidate for Rice University in Houston, said in a statement. “Moreover, with only one seismic station on Mars, we can not use methods that rely on seismic networks.”
The research team examined InSight’s seismology data using a technique called ambient noise autocorrelation, which is intended to produce the reflections produced at the boundaries of Martian zones below the crust.
The data indicated three main boundaries: between the Martian crust and mantle (at 22 miles and 35 kilometers below the lander), a transition zone between the minerals olivine and wadsleyite (at 690 to 727 miles as 1,110 to 1,170 km down), and the boundary between the mantle and the core (at 945 to 994 miles, as 1,520 km to 1,600 km down).
“The temperature at the oil-wadsleyite transition is an important key to building thermal models of Mars. From the depth of the transition we can easily calculate the pressure, and thus we can deliver the temperature, said Deng. The mantle-core boundary, he added, “can provide information about the evolution of the planet from both a chemical and thermal point of view.”
A study based on the research was published August 4 in Geophysical Research Letters.
Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.
