Details

Autor(en) / Beteiligte

• Daubar, I. J.
• Dundas, C. M.
• McEwen, A. S.
• Gao, A.
• Wexler, D.
• Piqueux, S.
• Collins, G. S.
• Miljkovic, K.
• Neidhart, T.
• Eschenfelder, J.
• Bart, G. D.
• Wagstaff, K. L.
• Doran, G.
• Posiolova, L.
• Malin, M.
• Speth, G.
• Susko, D.
• Werynski, A.

Titel

New Craters on Mars: An Updated Catalog

Ist Teil von

• Journal of geophysical research. Planets, 2022-07, Vol.127 (7), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2022

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• We present a catalog of new impacts on Mars. These craters formed in the last few decades, constrained with repeat orbital imaging. Crater diameters range from 58 m down to <1 m. For each impact, we report whether it formed a single crater or a cluster (58% clusters); albedo features of the blast zone (88% halos; 64% linear rays; 10% arcuate rays; majority dark‐toned; 4% light‐toned; 14% dual‐toned); and exposures of ice (4% definite; 2% possible). We find no trends in the occurrences of clusters with latitude, elevation, or impact size. Albedo features do not depend on atmospheric fragmentation. Halos are more prevalent at lower elevations, indicating an atmospheric pressure dependence; and around smaller impacts, which could be an observational bias. Linear rays are more likely to form from larger impacts into more consolidated material and may be enhanced by lower atmospheric pressure at higher elevations. Light‐ and dual‐toned blast zones occur in specific regions and more commonly around larger impacts, indicating excavation of compositionally distinct material. Surfaces covered with bright dust lacking cohesion are favored to form detectable surface features. The slope of the cumulative size frequency distribution for this data set is 2.2 for diameters >8 m (differential slope 2.9), significantly shallower than the slope of new lunar craters. We believe that no systematic biases exist in the Martian data set sufficient to explain the discrepancy. This catalog is complete at the time of writing, although observational biases exist, and new discoveries continue. Plain Language Summary We present a list of all the new impact craters on Mars. These craters formed in the last few decades, constrained with before and after images taken from orbiting spacecraft. Craters range in size from 58 m across down to smaller than can be measured. For each impact, we report whether it formed a single crater or a cluster of craters that were created by one impact event; whether the area around the impact is relatively bright or dark; what types of features are around the impact site, like rays or halos; and whether the impact excavated any water ice. We look at how these aspects vary with location on Mars and how that relates to how they might have formed. We find that fewer small craters compared to larger craters are currently forming on Mars than on the Moon. We examine several possible explanations, including known biases in the datasets, impacting populations, target material properties, and atmospheric effects, but none of these can explain the discrepancy. Key Points We present 1203 new impacts on Mars 1–58 m in diameter, 58% of which are clusters, with date constraints from orbital images Dark and light albedo features around new craters include halos and rays, some of which depend on location, surface properties, or size The slope of the size frequency distribution of new Martian craters is shallower than lunar craters, even considering systematic biases