Tumbling boulders may have provided NASA with evidence of earthquakes on Mars.
NASA first attempted to track 'marsquakes' with the Viking program in 1975, with its landers trying to detect any seismic activity on the Red Planet. Alas, the seismographs never picked up any clear activity as a result of the Martian wind.
Over the ensuing decades, unconfirmed activity has been detected, including three candidate seismic events between March and April 2019 said to be similar to the moonquakes during the Apollo program. Now, boulders may be the key to definitive evidence of quakes on our neighbouring world.
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A study published in Geophysical Research Letters, titled 'Boulder Fell Ejecta: Present Day Activity On Mars', took a closer look at the tracks left by falling boulders on Mars, and whether they're indicative of any seismic activity.
They usually only last a few years as a result of being swept away or covered by dust and sand, but this marks the first time rockfalls - named 'boulder fall ejecta' - have been spotted on Mars, coming after similar 'ejecta' was discovered on the moon.
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Using photos captured between 2006 and 2020 by a camera onboard the Mars Reconnaissance Orbiter HiRISE, the research time could 'discriminate individual boulders', Dr. Vijayan, one of the leaders of the project, told The New York Times.
During their research, they discovered more than 4,500 boulder tracks, with some as long as a mile-and-a-half. While again unconfirmed, tracks like these have been indicative of seismic activity in the past, meaning previous notions about Mars' state of activity over the past 15 years may be false. 'For a long time, we thought that Mars was this cold, dead planet,' Brown University planetary scientist Ingrid Daubar also said.
'All the BFE tracks mapped in this study formed side-by-side with the older tracks without BFE, which suggests the boulder falls are frequent and occurring over decades on Mars. From our survey, we find rockfall triggered by wind, thermal cracking and seismic shaking are reasonable triggers for the recent falls causing BFE. Our observations suggest that the present day occurrence of boulder falls is wide spread, and that they are happening more frequently,' the study notes.
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Alfred McEwen, a scientist with the University of Arizona, backs the findings of the study, citing how the rockfalls were discovered in a volcanic region of the planet. 'These giant masses of dense rock loaded up on the surface creates stresses throughout the surrounding crust of Mars,' he said.
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Cameron Frew