It was discovered that Mars had a magnetic field earlier than previously expected, 4.5 billion years ago!

[Mobile software: Bo Ke Yuan] Mars had a global magnetic field much earlier in its history than scientists previously knew. A planet's global magnetic field comes from what scientists call a dynamo: a flow of molten metal that creates an electric current within the planet's core. On Earth, the dynamo keeps a compass pointing north, but Mars' dynamo has been off for a very long time. New findings by University of British Columbia researchers, in collaboration with scientists in the United States and France, bring us closer to understanding the exact timing and duration of the Martian dynamo, and their research is published in the journal Science Advances.

"We found that the Martian dynamo was operating 4.5 billion years ago and 3.7 billion years ago," said Anna Mittelholz, a postdoctoral fellow in the Department of Earth, Ocean and Atmospheric Sciences at the University of British Columbia and the study's lead author. "The dynamo is a big part of planetary evolution, and the new discovery is very different from what was thought until now. The dynamo can tell us something about the planet's thermal history, evolution, and how it got to where it is today, which is unique to the four terrestrial planets: Earth, Mars, Venus and Mercury. Clues about the planet's magnetic history are in magnetized rocks on its surface and beneath it."

Rocks are like recorders, especially volcanic rocks. They start out as molten lava, but as they cool and solidify in response to a magnetic field, the minerals in the rock align with the global magnetic field. By dating these rocks, scientists can estimate whether a dynamo was active when the rocks were in place. Magnetism in certain rocks on the Martian surface suggests that the Martian dynamo was active between 4.3 billion and 4.2 billion years ago, but the absence of magnetism over three large basins that formed 3.9 billion years ago led most scientists to believe the dynamo was inactive at the time. Scientists at the University of British Columbia analyzed new satellite data and found clear evidence:

"We have these two observations, which point to the earliest known dynamo in Mars' history, and to the emergence of a dynamo 500 million years after many people thought it had gone out," said Katherine Johnson, a professor and senior scientist in the Department of Earth, Ocean and Atmospheric Sciences at the Planetary Science Institute in Tucson, Arizona.

The researchers offer two possible explanations for the absence of a magnetic field over the basin: the dynamo could have stopped before the basin formed and then restarted before Lucas Planum formed, or the impact that created the basin simply moved parts of the crust that contain minerals that can carry strong magnetism. The new data for this study came from the Martian Atmosphere and Volatile Evolution Satellite (MAVEN). Earlier data on magnetism on Mars were collected by the Mars Global Surveyor satellite, which orbited Mars between 1999 and 2006, mostly at 400 km above the Martian surface.

Launched in 2013, Maven orbits about 135 kilometers above the surface, picking up weaker signals that MGS can't detect. Maven is able to pick up signals from smaller features in and near the surface, which helps researchers distinguish whether the magnetism is coming from those features or from older rocks buried deeper in the Martian crust. These new findings have researchers wondering, what would be revealed if a satellite got closer? This study focused on two particular features, but craters on Mars still have stories to tell everywhere. In the future, exploration could advance from satellites to drones or balloons, providing even more detailed data.

Boco Park | Research/From: University of British Columbia

The study was published in the journal Science Advances

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