Scientists get intimate view of havoc that comet C/2013 A1’s passing wreaked on magnetic environment around Mars

A few weeks prior to the historic encounter of comet C/2013 A1 with the Red Planet in October 2014, NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made an entry into Mars’ orbit.

With a motive to keep sensitive equipment aboard MAVEN safe from probable damage, some instruments were switched off at the time of the flyby. Similar procedure was followed for other Mars orbiters as well.

However, some instruments, including MAVEN's magnetometer, were on, and conducted observations being on the front-row at the time of the comet's remarkably close flyby.

Thanks to the one-of-a-kind opportunity that allowed scientists to take a close look at the havoc that the passing of the comet caused on the magnetic environment, or magnetosphere, around the planet. It was temporary, but quite intense.

Jared Espley, a MAVEN science team member at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said, “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”.

Unlike our planet, the Red Planet doesn’t have a strong magnetosphere cover. Mars’ atmosphere provides some protection by redirecting the solar wind surrounding the planet, in a way similar to a rock diverting the water flow in a creek.

Such a thing happens because at very high altitudes, the atmosphere of Mars is composed of plasma, a layer made up of electrically charged particles and gas molecules.

The solar wind’s charged particles come in touch with this plasma, and the mixing up and movement around all these charges generate currents. Similar to the currents in simple electrical circuits, such moving charges lead to a magnetic field, which in the case of Mars is very weak.