1. Extensive Secondary Cratering From the InSight Sol 1034a Impact Event.
- Author
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Grindrod, P. M., Daubar, I. J., Fernando, B., Kim, D., Collins, G. S., Stähler, S. C., Wojcicka, N., Posiolova, L. V., Froment, M., Beucler, É., Sansom, E., Garcia, R., and Zenhäusern, G.
- Subjects
IMPACT craters ,MARTIAN craters ,SOLAR system ,IMAGING systems in seismology ,ALBEDO ,LUNAR craters - Abstract
Impact cratering is one of the fundamental processes throughout the history of the Solar System. The formation of new impact craters on planetary bodies has been observed with repeat images from orbiting satellites. However, the time gap between images is often large enough to preclude detailed analysis of smaller‐scale features such as secondary impact craters, which are often removed or buried over a short time period. Here we use a seismic event detected on Mars by the NASA InSight mission to investigate secondary cratering at a new impact crater. We strengthen the case that the seismic event that occurred on Sol 1034 (S1034a) is the result of a new impact cratering event. Using the exact timing of this event from InSight, we investigated the resulting new impact crater in orbital image data. The S1034a impact crater is approximately 9 m in diameter but is responsible for over 900 secondary impact events in the form of low albedo spots that are located at distances of up to almost 7 km from the primary crater. We suggest that the low albedo spots formed from relatively low energy ejecta, with individual ejecta block velocities less than 200 m s−1. We estimate that the low albedo spots, the main evidence of secondary impact processes at this new impact event, fade within 200–300 days after formation. Plain Language Summary: On 23 October 2021, the seismometer instrument on the NASA InSight lander detected a seismic event on Mars. The nature of the seismic signal shared characteristics with other events attributed to meteorites impacting the surface of Mars. Reanalysis of images taken by cameras on orbiting spacecraft identified a new impact crater whose location and time of formation matched with the seismic analysis. Our study shows that this 9 m diameter crater has produced over 900 additional, or secondary, impact features up to 7 km away. These secondary features are characterized as being dark spots, often with a tail that points away from the direction of impact, which fade over time. The relatively high number of secondary features from this small impact event is likely due to the low porosity of the rock that was impacted at the surface. We estimate that the dark spots disappear in 200–300 days, thus removing a key set of features used in identifying new impact events on Mars. This timescale places useful limits for future image searches attempting to identify small new impact craters on Mars, and suggests that other such small impact events have been captured in existing data sets and not yet recognized. Key Points: A new 9‐m‐diameter impact crater on Mars identified with in situ seismic and orbital image dataOver 900 low albedo spots identified as a result of secondary ejecta processesSmall impact events have likely been captured in existing data sets and not yet recognized [ABSTRACT FROM AUTHOR]
- Published
- 2024
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