New research from Harvard University suggests that Mars might have been habitable more recently than scientists previously believed.
The study, published in Nature Communications, reveals that Mars’ protective magnetic field may have lasted until about 3.9 billion years ago—several hundred million years longer than previous estimates.
A magnetic field is crucial for making a planet habitable because it protects it from harmful cosmic rays.
Earth’s magnetic field, for example, is generated by the movement of liquid iron in its core, creating what’s known as a “dynamo.”
Scientists believe Mars had a similar dynamo in its early history, which could have shielded the planet and supported life.
Sarah Steele, a graduate student at Harvard, and her team used computer simulations to better understand the timeline of Mars’ magnetic field.
Along with senior author Roger Fu, an associate professor at Harvard, they focused on the formation of large impact craters on Mars’ surface. These craters are weakly magnetized, leading earlier researchers to assume that the Martian dynamo had already shut down when these craters formed.
However, Steele’s team challenges this assumption.
They believe these craters could have formed during a period of “magnetic reversal” when the planet’s magnetic poles were flipping between north and south, which is a natural occurrence that also happens on Earth every few hundred thousand years.
During such reversals, the magnetic field temporarily weakens, which could explain why these craters have only faint magnetic signals today.
The team’s findings build on their previous work, which studied a famous Martian meteorite called Allan Hills 84001.
By examining thin slices of the meteorite with advanced techniques, they inferred that Mars’ magnetic field persisted until about 3.9 billion years ago. This new evidence challenges the long-standing belief that Mars’ magnetic field shut down around 4.1 billion years ago.
Steele acknowledges that questioning a widely accepted theory can be daunting, but she appreciates the openness of the planetary science community to new ideas.
She emphasized that understanding planetary magnetic fields is crucial because they offer insights into the deep interiors and early histories of planets, which helps scientists understand the solar system as a whole.
This new study gives scientists more reason to believe that Mars might have been habitable longer than previously thought. It opens up new possibilities for future exploration and study of the red planet’s past and its potential for life.
