Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamo
Abstract Understanding the longevity of Mars’s dynamo is key to interpreting the planet’s atmospheric loss history and the properties of its deep interior. Satellite data showing magnetic lows above many large impact basins formed 4.1-3.7 billion years ago (Ga) have been interpreted as evidence that...
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2024-08-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-024-51092-4 |
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| author | S. C. Steele R. R. Fu A. Mittelholz A. I. Ermakov R. I. Citron R. J. Lillis |
| author_facet | S. C. Steele R. R. Fu A. Mittelholz A. I. Ermakov R. I. Citron R. J. Lillis |
| author_sort | S. C. Steele |
| collection | DOAJ |
| description | Abstract Understanding the longevity of Mars’s dynamo is key to interpreting the planet’s atmospheric loss history and the properties of its deep interior. Satellite data showing magnetic lows above many large impact basins formed 4.1-3.7 billion years ago (Ga) have been interpreted as evidence that Mars’s dynamo terminated before 4.1 Ga—at least 0.4 Gy before intense late Noachian/early Hesperian hydrological activity. However, evidence for a longer-lived, reversing dynamo from young volcanics and the Martian meteorite ALH 84001 supports an alternative interpretation of Mars’s apparently demagnetized basins. To understand how a reversing dynamo would affect basin fields, here we model the cooling and magnetization of 200-2200 km diameter impact basins under a range of Earth-like reversal frequencies. We find that magnetic reversals efficiently reduce field strengths above large basins. In particular, if the magnetic properties of the Martian mantle are similar to most Martian meteorites and late remagnetization of the near surface is widespread, >90% of large ( > 800 km diameter) basins would appear demagnetized at spacecraft altitudes. This ultimately implies that Mars’s apparently demagnetized basins do not require an early dynamo cessation. A long-lived and reversing dynamo, unlike alternative scenarios, satisfies all available constraints on Mars’s magnetic history. |
| format | Article |
| id | doaj-art-9c919e9f395c41de8a30120ce99bc6de |
| institution | Kabale University |
| issn | 2041-1723 |
| language | English |
| publishDate | 2024-08-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Nature Communications |
| spelling | doaj-art-9c919e9f395c41de8a30120ce99bc6de2025-01-05T12:36:09ZengNature PortfolioNature Communications2041-17232024-08-0115111610.1038/s41467-024-51092-4Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamoS. C. Steele0R. R. Fu1A. Mittelholz2A. I. Ermakov3R. I. Citron4R. J. Lillis5Department of Earth and Planetary Sciences, Harvard UniversityDepartment of Earth and Planetary Sciences, Harvard UniversityDepartment of Earth and Planetary Sciences, Harvard UniversityDepartment of Aeronautics and Astronautics, Stanford UniversityMIT/NASA GoddardSpace Sciences Laboratory, University of California, BerkeleyAbstract Understanding the longevity of Mars’s dynamo is key to interpreting the planet’s atmospheric loss history and the properties of its deep interior. Satellite data showing magnetic lows above many large impact basins formed 4.1-3.7 billion years ago (Ga) have been interpreted as evidence that Mars’s dynamo terminated before 4.1 Ga—at least 0.4 Gy before intense late Noachian/early Hesperian hydrological activity. However, evidence for a longer-lived, reversing dynamo from young volcanics and the Martian meteorite ALH 84001 supports an alternative interpretation of Mars’s apparently demagnetized basins. To understand how a reversing dynamo would affect basin fields, here we model the cooling and magnetization of 200-2200 km diameter impact basins under a range of Earth-like reversal frequencies. We find that magnetic reversals efficiently reduce field strengths above large basins. In particular, if the magnetic properties of the Martian mantle are similar to most Martian meteorites and late remagnetization of the near surface is widespread, >90% of large ( > 800 km diameter) basins would appear demagnetized at spacecraft altitudes. This ultimately implies that Mars’s apparently demagnetized basins do not require an early dynamo cessation. A long-lived and reversing dynamo, unlike alternative scenarios, satisfies all available constraints on Mars’s magnetic history.https://doi.org/10.1038/s41467-024-51092-4 |
| spellingShingle | S. C. Steele R. R. Fu A. Mittelholz A. I. Ermakov R. I. Citron R. J. Lillis Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamo Nature Communications |
| title | Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamo |
| title_full | Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamo |
| title_fullStr | Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamo |
| title_full_unstemmed | Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamo |
| title_short | Weak magnetism of Martian impact basins may reflect cooling in a reversing dynamo |
| title_sort | weak magnetism of martian impact basins may reflect cooling in a reversing dynamo |
| url | https://doi.org/10.1038/s41467-024-51092-4 |
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