The Mars of today is an arid and (presumably) lifeless world. That was not always the case, though. Evidence from Curiosity and other missions proves Mars once had an atmosphere and liquid water, but then its magnetic field vanished. The InSight lander has now shown there’s still more magnetic field activity on Mars than expected — about 10 times more, in fact.
On Earth, the strong magnetic field protects us from dangerous radiation and forms a cocoon that guards against the solar wind. Without a magnetic field, the solar wind stripped away most of Mars’ atmosphere. Scientists knew there was still some residual magnetic field activity on the red planet, but InSight is the first mission to measure it accurately.
InSight landed on Mars in late 2018 and soon after became the first mission to take seismic readings on another planet. It also has a magnetic sensor that NASA used to filter out magnetic interference in those readings. However, researchers have now managed to use that data to scan the planet’s magnetic field strength. Before this, the best estimate of Mars’ magnetic field came from satellite missions that orbited high above the atmosphere. The international research analyzing this data found Mars’ magnetic field is 10 times stronger than the satellite models suggested.
On Earth, the magnetic field emanates from the convection currents in the planet’s molten core, known as a geodynamo. Mars doesn’t have one of those, so the team was interested to find the source of the unexpectedly strong magnetic field. Based on data from past missions, we believe Mars’ magnetic field ebbed about 4.2 billion years ago. Most of the rocks on and near the surface are younger than that, so they would not have been exposed to the field. The team, therefore, believes the residual magnetic field emanates from very old rocks that are at least several hundred feet below the surface. With additional data from other missions, we could learn more about the planet’s internal structure and geological history.
While the magnetic field on Mars is stronger than expected, it’s still not going to keep the solar wind at bay. That’s actually a good thing for studying the space around Mars. The red planet’s lack of a local magnetic field allowed InSight to gather data on how the solar wind affects the surface. That could provide essential data that helps future human explorers protect themselves while on Mars.
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