According to new research using data from NASA’s Mars Atmosphere and Volatile Evolution Mission (MAVEN) spacecraft, the Red Planet has an invisible magnetic tail — or magnetotail — that is twisted by interaction with the solar wind.
Artist’s conception of the complex magnetic field environment at Mars. Yellow lines represent magnetic field lines from the Sun carried by the solar wind, blue lines represent Martian surface magnetic fields, white sparks are reconnection activity, and red lines are reconnected magnetic fields that link the surface to space via the Martian magnetotail. Image credit: Anil Rao / University of Colorado / MAVEN / NASA’s Goddard Space Flight Center.
“We found that Mars’ magnetotail is unique in the Solar System,” said lead author Dr. Gina DiBraccio, of NASA’s Goddard Space Flight Center.
“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.”
Mars lost its global magnetic field billions of years ago and now just has remnant ‘fossil’ magnetic fields embedded in certain regions of its surface.
Dr. DiBraccio and co-authors found that Mars’ magnetotail is formed when magnetic fields carried by the solar wind join with the magnetic fields embedded in the Martian surface in a process called magnetic reconnection.
“Our model predicted that magnetic reconnection will cause the Martian magnetotail to twist 45 degrees from what’s expected based on the direction of the magnetic field carried by the solar wind,” Dr. DiBraccio said.
“When we compared those predictions to MAVEN data on the directions of the Martian and solar wind magnetic fields, they were in very good agreement.”
According to the team, the magnetic reconnection also might propel some of Mars’ atmosphere into space.
“Mars’ upper atmosphere has electrically charged particles (ions). Ions respond to electric and magnetic forces and flow along magnetic field lines,” the researchers said.
“Since the Martian magnetotail is formed by linking surface magnetic fields to solar wind fields, ions in the Martian upper atmosphere have a pathway to space if they flow down the magnetotail.”
“Like a stretched rubber band suddenly snapping to a new shape, magnetic reconnection also releases energy, which could actively propel ions in the Martian atmosphere down the magnetotail into space.”
Since Mars has a patchwork of surface magnetic fields, scientists had suspected that the Martian magnetotail would be a complex hybrid between that of a planet with no magnetic field at all and that found behind a planet with a global magnetic field.
Extensive MAVEN data on the Martian magnetic field allowed Dr. DiBraccio and colleagues to be the first to confirm this.
They will report their results today at the 49th Meeting of the AAS Division for Planetary Sciences in Provo, Utah.
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Gina A. DiBraccio et al. 2017. The complex magnetic field configuration of the Martian magnetotail as observed by MAVEN. 49th Meeting of the AAS Division for Planetary Sciences, abstract # 505.02
