A Mars comet flyby wreaked havoc as it streaked by after the magnetic field was so strong that it temporarily merged in orbit for several hours. It suggests the passing ball of ice may even have blown away some of it’s atmosphere, according to Tech Times.
In 2014 a comet called C/2013 A1, also known as Siding Spring, passed remarkably close to the red planet. Sliding Spring passed within 87,000 miles of Mars, less than half the distance between earth and its moon, and much closer than any other has ever come to earth.
Now a study published by NASA has revealed just how much havoc the Mars comet flyby was on the planet’s magnetic field. The rock came from the Oort Cloud, which is made up of material left over from the formation of the solar system.
Oort Cloud material is scattered through a vast region that begins outside the orbits of Neptune and Pluto and extends a substantial fraction of the distance to Proxima Centauri, our closest neighbouring star.
NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft entered orbit just weeks before its space rock encounter. To protect sensitive equipment aboard MAVEN from possible harm, some instruments were turned off during the flyby. But a few instruments, including MAVEN’s magnetometer, to measure the strength and direction of magnetic fields, remained on during its brush.
The space rock was surrounded by a magnetic field produced by the solar wind, a stream of energised, charged particles flowing outward from the Sun, interacting with the plasma generated in the coma — gas flowing from a its nucleus as it is heated by the sun.
Comet Siding Spring’s nucleus is a clump of ice and rock, which measures no more than a third of a mile (around half a kilometre), but the coma stretches out more than 600,000 miles, a million kilometres, in every direction.
The densest part of the coma, the inner region near the nucleus, is the part of an asteroid that’s visible to telescopes and cameras as a big fuzzy ball. When the comet flyby passed, its coma washed over for several hours, with the dense inner coma nearly reaching the surface.
The planet was flooded with an invisible tide of charged particles from the coma, and the powerful magnetic field around the astroid temporarily merged with — and overwhelmed — it’s own weak one. Research published this week in Geophysical Research Letters outlined the effect of its powerful magnetic field.
“Comet Siding Spring plunged the magnetic field around Mars into chaos,” said Jared Espley, a MAVEN science team member at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
“We think the encounter blew away part of Mars’ upper atmosphere, much like a strong solar storm would.”
Mars isn’t shielded by a strong magnetosphere generated, unlike earth. It has a weak magnetosphere because of a layer of plasma in its outer atmosphere which interacts with solar wind.
As the planet’s magnetosphere, which is normally draped neatly over the planet, started to react to the astroid’s approach, some regions began to realign to point in different directions. With the space rock’s advance, these effects built in intensity, almost making the planet’s magnetic field flap like a curtain in the wind.
By the time the plasma from the Mars comet flyby was densest, the red planet’s magnetic field was in chaos. Even hours after its departure, some disruption continued to be measured.