In August of this year, new findings published in the journal Nature Communications shed light on the ancient magnetic field of Mars, suggesting it persisted much longer than previously believed, Live Science reported. The study, led by Sarah Steele, a graduate student at Harvard University's Griffin Graduate School of Arts and Sciences, used computer simulations and principles of paleomagnetism to estimate the age of Mars's global magnetic field, or dynamo, the Harvard Gazette noted.
Steele and her team proposed that Mars's global magnetic field did not disappear 4.1 billion years ago, as previously thought, but lasted until at least 3.9 billion years ago. "We are basically showing that there may not have ever been a good reason to assume Mars' dynamo shut down early," Steele said, according to Earth.com. This revelation suggests that Mars may have remained habitable for hundreds of millions of years longer than scientists had believed.
The magnetic field of a planet plays a crucial role in maintaining conditions suitable for life. On Earth, the magnetic field acts as a shield that deflects charged particles emitted by the solar wind and cosmic rays, SciencePost explained. Similarly, Mars's magnetic field would have contributed to maintaining a dense atmosphere and the presence of liquid water on its surface, overlapping with conditions suitable for life, according to Space.com.
The team's conclusions are based on a re-examination of large impact basins on Mars, which show weak magnetic signals. Scientists traditionally interpreted these weak signals as evidence that the basins formed after Mars's dynamo had shut down. However, Steele's team modeled the cooling and magnetization processes of these basins and discovered that the formation of the craters indicates a longer period of existence for Mars's magnetic field.
The researchers propose that the impact craters formed during a period of magnetic polarity reversal, where the north and south poles switch places, SciencePost reported. During such reversals, ferromagnetic minerals become uncertain in their alignment, making the magnetic field appear weak or nonexistent. This phenomenon could account for the weak magnetic fields detected in Martian craters.
"Planetary magnetic fields are our best probe to answer many of those questions, and one of the only ways we have to learn about the deep interiors and early histories of the planets," said Steele, according to Earth.com.
The loss of Mars's magnetic field marked a critical turning point in the planet's evolution. Without its global magnetic field, Mars could not ward off the solar wind, which began stripping away its atmosphere and water, resulting in a drop in atmospheric pressure, Space.com reported.
The article was written with the assistance of a news analysis system.