Analysis of sites on Mars show that the red planet’s protective field was switched off half a billion years ago, and NASA scientists say they know why. An impact basin deep enough to swallow Mount Everest in Valles Marineris highlight what might be the results of a ancient asteroid collision with the Red Planet switching off its magnetic field, bathing the Red Planet in harmful radiation, and eroding its atmosphere by particles streaming from solar winds.
Today, Mars is a frigid desert world with a carbon dioxide atmosphere 100 times thinner than Earth’s. But evidence suggests that in the early history of our solar system, Mars’ surface likely hosted an ocean as deep as the Mediterranean Sea. As the planet’s atmosphere thinned, however, most of the ocean was lost to space.
A study by scientists at Australia National University (ANU) on the magnetic fields of exoplanets has found that most planets discovered in other solar systems are unlikely to be as hospitable to life as Earth. Plants and animals would not survive without water on Earth. The sheer strength of Earth’s magnetic field helps to maintain liquid water on our blue planet’s surface, thereby making it possible for life to thrive.
Associate Professor Charley Lineweaver, a co-author, said scientists had detected hundreds of rocky exoplanets during the past decade. “Do any of these planets have water on their surfaces? Do they harbor life? To help answer these questions, we decided to model their magnetic fields. Strong magnetic fields could protect and preserve a wet surface in a way that weak fields cannot.”
Scientists from the ANU Research School of Astronomy and Astrophysics modeled the magnetic fields of exoplanets—planets beyond our solar system—and found very few have a magnetic field as strong as Earth.
They contend that techniques for finding exoplanets the size of Earth are more likely to find slowly rotating planets locked to their host star in the same way the Moon is locked to Earth, with the same side always facing their host star.
“Magnetic fields appear to play an essential role in making planets habitable, so I wanted to find out how Earth’s magnetic field compared to those of other potentially habitable planets,” said lead author Sarah McIntyre.
McIntyre said Earth’s strong magnetic field had probably played an important role in protecting the atmosphere from the solar wind and keeping the planet wet and habitable. “Venus and Mars have negligible magnetic fields and do not support life, while Earth’s magnetic field is relatively strong and does,” she said. “We find most detected exoplanets have very weak magnetic fields, so this is an important factor when searching for potentially habitable planets.”
Co-researcher Associate Professor Michael Ireland said finding planets with strong magnetic fields was critical to the search for life elsewhere in the universe. “Finding and characterizing planets most likely to be wet and temperate will require ambitious yet feasible space missions,” he said.
The Daily Galaxy, Sam Cabot via the Royal Astronomical Society