A Mars comet flyby caused a merging of magnetic fields from the comet and Mars. NASA was in the right place at the right time and was able to study what happens to a planet when a comet comes extremely close to a planet. The Mars Atmosphere and Volatile Evolution spacecraft (MAVEN) was in an orbit around Mars shortly before comet C/2013 A1 (Comet Siding Spring) was set to do its flyby of the red planet.
— NASA’s MAVEN Mission (@MAVEN2Mars) March 11, 2016
NASA was fully aware that this comet was coming, so they were able to take precautions to ensure MAVEN was protected. Most of the scientific instruments were turned off on the spacecraft out of fear that the magnetic field of the comet would destroy the sensitive equipment. Of the very few instruments that remained on, the magnetometer would be the most important one. Jared Espley, a MAVEN science team member at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, discussed what the scientists discovered during the flyby.
“Comet Siding Spring plunged the magnetic field around Mars into chaos. We think the encounter blew away part of Mars’ upper atmosphere, much like a strong solar storm would. The main action took place during the comet’s closest approach. But the planet’s magnetosphere began to feel some effects as soon as it entered the outer edge of the comet’s coma.”
Comet Siding Spring originated in the Oort Cloud. The magnetic field that surrounded the comet was created by streams of charged particles coming from the Sun. These particles mixed with the plasma that was created from the gas around the nucleus of the comet. This part of the comet is known as the coma. As the comet gets closer to the sun, more gas is produced in the coma.
The magnetic field on Mars is nowhere as strong as the magnetic field surrounding Earth. The outer atmosphere of Mars is layered with a plasma that interacts with the solar wind created by the Sun. When the comet neared Mars, the two magnetic fields merged into one over the course of several hours. The comet’s coma covered a large portion of Mars and the innermost part of the coma almost reached as far as the surface of the red planet.
As the two magnetic fields interacted, the magnetic field of Mars was realigning itself. During the strongest part of the interaction, the magnetic field of Mars was so disturbed that it moved similarly to a curtain flapping in a breeze. Mars did not regain its normal magnetic field until several hours after the comet left its orbit.
— Jack Morgan (@PollsMedia) March 12, 2016
The strong magnetic field interruption was similar to what would happen during a strong solar storm. NASA scientists have been trying to study how solar storms impact the magnetic field on Mars and this was a perfect opportunity to learn more. Bruce Jakosky, MAVEN’s principal investigator from the University of Colorado commented further on what MAVEN’s mission on Mars will be.
“With MAVEN, we’re trying to understand how the sun and solar wind interact with Mars. By looking at how the magnetospheres of the comet and of Mars interact with each other, we’re getting a better understanding of the detailed processes that control each one.”
[Image via NASA/Goddard]