Why is NASA exploring Mars’ magnetic field?
Billions of years ago, rivers flowed across Mars and lakes dotted its surface. The planet was warmer and — maybe — hospitable to life.
Back then, Mars had a thick atmosphere instead of the tenuous envelope surrounding it today. This atmosphere helped at least intermittently maintain the planet’s liquid water, which is essential for life as we know it. But somehow, over the course of tens or hundreds of millions of years, almost all of Mars’ atmosphere was lost.
Today, many scientists think that Mars lost its atmosphere in part because it lacked (or lost) the right kind of magnetic field. Around Earth, such a magnetic field shields us from a constant flow of charged particles unleashed by the Sun, called the solar wind. But on Mars, the solar wind could have instead hit the planet’s atmosphere in a way that helped energize lots of it into space.