A NASA spacecraft has discovered that the magnetic tail of Mars is twisted by the solar wind, giving it a unique tail unlike anything seen in the Solar System.

The discovery was made by NASA’s Mars Atmosphere and Volatile Mission (MAVEN) spacecraft, which is currently in orbit around the Red Planet. This spacecraft has previously shed light on how Mars lost its atmosphere.

This time around, a team from NASA reported at the 49th annual meeting of the American Astronomical Society’s Division for Planetary Sciences in Provo, Utah what the magnetotail of Mars looks like.

Mars does not have a global magnetic field anymore, having lost it billions of years ago through a process that’s not quite understood yet. This led to the loss of its atmosphere, and ultimately the evaporation of the oceans on its surface.

However, it still has a remnant fossil magnetic field that’s embedded in parts of the surface. In this study, the researchers found that the solar wind interacted with this field to produce a tail behind the planet, in a process called magnetic reconnection.

We are just starting to understand this process in Earth’s magnetic field. It basically involves solar wind and Earth’s magnetic field lines (or Mars, in this case) snapping together, releasing a huge amount of energy. On Earth, this process drives our aurora.

On Mars, however, this process appears to be producing a twisted tail. This is because of the patchwork surface magnetic fields, which creates a sort of hybrid tail between that of Earth and that of Venus, which has a scaled down version of ours. Venus has an induced magnetic field caused by the Sun.

“We found that Mars’ magnetic tail, or magnetotail, is unique in the Solar System,” said Gina DiBraccio of NASA’s Goddard Space Flight Center in Greenbelt, Maryland in a statement.

“It’s not like the magnetotail found at Venus, a planet with no magnetic field of its own, nor is it like Earth’s, which is surrounded by its own internally generated magnetic field. Instead, it is a hybrid between the two.” 

The team now wants to see how reconnection has affected atmospheric loss on Mars, by looking if the escaped particles correspond to areas of reconnection. They also want to find out how the surface magnetic fields affect the tail as Mars rotates.

“Mars is really complicated but really interesting at the same time,” said DiBraccio.