slideshow 1 slideshow 2 slideshow 3 slideshow 4 slideshow 5 slideshow 6

You are here

Timing of Ancient Mars Magnetic Field Determined

MAVEN at mars

This artist concept depicts NASA’s Mars Atmosphere and Volatile EvolutioN MAVEN spacecraft near Mars.



A Martian magnetic field was in place much earlier – as well as much later – than scientists had thought, according to the Science Advances paper “Timing of the Martian dynamo: New constraints for a core field at 4.5 and 3.7 Ga ago” ( on which PSI’s Senior Scientist Catherine Johnson is an author. 

A planet’s global magnetic field arises from what scientists call a dynamo: a flow of molten metal within the planet’s core that produces an electrical current. On Earth, the dynamo is what makes compass needles point north. But Mars’ dynamo, and magnetic field, has been extinct for billions of years. 

"We have these two observations that point to a dynamo at the earliest known time in Mars' history, and a dynamo that was present almost half a billion years after many people thought it had already switched off," Johnson said. The Martian dynamo operated at 4.5 billion years ago (4.5 Ga) and 3.7 billion years ago. 

Data from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) orbiter showed clear evidence of a magnetic field coming from the Lucus Planum lava flow that formed about 3.7 billion years ago – much later than at other areas studied. 

“If a rocky planet or moon has a global magnetic field like on Earth either today or sometime in the past, it tells us about the planet’s deep interior at that time.  Furthermore, new results for the dynamo at 3.7 Ga suggest that the Martian dynamo could have been active at a time of very different climatic conditions on Mars, in particular when many of the valley networks formed,” Johnson said.

May 31, 2020
Page maintained by
fischer [at] (A. Fischer)

PSI, a Nonprofit Corporation 501(c)(3), and an Equal Opportunity/M/F/Vet/Disabled/Affirmative Action Employer.
Corporate Headquarters: 1700 East Fort Lowell, Suite 106 * Tucson, AZ 85719-2395 * 520-622-6300 * FAX: 520-622-8060
Copyright © 2021 . All Rights Reserved.