Mars: meteorite impacts provide InSight into planet’s interior

Mars insight lander (artist impression)
Mars InSight Lander (artist impression). Credit: NASA/JPL-Caltech

Scientists have for the first time been able to find impact sites of incoming Martian meteorites using their sound and seismic waves, which might lead to greater understanding of the makeup of the planet they are headed for.

NASA’s InSight Mars Lander has been studying the red planet’s interior, from its surface, since November 26, 2018. Short for ‘Interior Exploration using Seismic Investigations, Geodesy and Heat Transport’, InSight has been using sensitive instruments to detect seismic waves, heat flow and accurate measurements of the shape and size of the planet – or, as NASA describes it, “the planet’s pulse, circulation and reflexes.”

Now, with the help of the Mars Reconnaissance Orbiter (MRO), which has been circling around Mars for the past 16 and a half years, researchers have been able to use data on waves travelling through the air and interior of the planet to estimate and confirm the location of an impact site of four incoming meteorites.

Crater on surface mars as seen by the mars reconnaissance orbiter
An impact crater captured from HiRISE instrument aboard the Mars Reconnaissance Orbiter in 2013. Credit: NASA/JPL-Caltech/University of Arizona

When energy travels through solids and gasses (such as the interior of planets or through air), it does so in the form of waves. When the energy waves encounter a new material – a new composition, pressure or temperature – some energy bounces off the interface, while some energy travels through into the new material, but with a different speed and at a different angle. This results in waves from an impact arriving at a detector at different times and from different directions.

A collaboration of researchers from Curtin University in Australia and the Université de Toulouse in France have analysed InSight lander seismometer data from 4 meteorite impacts and used the different arrival times of the wave fronts from each impact to estimate the location of the impact. They then compared this estimate with images from the MRO and were able to confirm crater impact sites – a first for planetary seismology.

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Using this technique, suggest the researchers, will enable planetary scientists to understand more about how impacts shape the surface of planets and deliver gasses to the planet over time. Knowing the size of the craters and the energy of the waves created, also provides information on the relationship between size of the colliding body and the overall impact on the surface in addition to providing valuable insight into the composition and properties of the interior of Mars.

Comparing these results with previous seismic data from the Moon suggests this technique could be applied to other planets to help scientists understand more about their interiors and characteristics.

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