Mars as we know it is a cold, dry planet, incapable of hosting life. But scientists believe this wasn’t always the case, and a recent study suggests that the period during which the Red Planet may have had liquid water on its surface — and the chance of life — was longer than previously believed.
A more detailed examination of a previously studied martian meteorite reveals the possible underpinnings of such a compelling prospect. Researchers in the paleomagnetics lab of Professor Roger Fu, John L. Loeb Associate Professor of the Natural Sciences, have uncovered evidence that Mars had a global magnetic field, much like Earth’s, for hundreds of millions of years longer than was once believed. Such a field can deflect harmful cosmic rays, enabling the possibility of an atmosphere, with all that implies.
“On Earth, our magnetic field seems to do a good job of shielding our atmosphere from space radiation and solar wind,” said Sarah Steele, a third-year graduate student in Earth and planetary sciences and first author of “Paleomagnetic evidence for a long-lived, potentially reversing martian dynamo at ~3.9 Ga,” published in May in Science Advances. “We think that’s part of what keeps the Earth surface habitable.”
While it is still unknown if this happened on Mars, the new timeline increases the possibility. The research team looked for records of the planet’s magnetic field, which would represent evidence of an early martian dynamo. The dynamo, she explained, describes the way liquid in the planet’s core moves to make strong magnetic fields around the planet. “If the dynamo was longer-lived on Mars and if it played the same role, that may have helped keep the surface habitable longer. But on the other hand, the magnetic fields around Mars could have functioned really differently — maybe they even helped the atmosphere escape to space.”
Previous evidence had suggested that Mars had lost its dynamo — and its accompanying strong, planet-encompassing magnetic fields — 4.1 billion years ago, Steele said. However, with the use of an innovative new quantum magnetic field microscope, the researchers were able to place the loss at 3.9 billion years ago or later. “Those sound very close together,” she said, of the dates. “But a giant chunk of the stuff we are interested in, such as the questions about water, is in that window.”