Earlier last month, on Oct. 19, researchers from the world's top space agencies were able to catch a glimpse at one of the rarest sights in space. Coming from the outer Oort Cloud, at the very edge of our solar system, young comet Siding Spring passed by Mars rather closely on its first orbit around the sun; giving Mars orbiters a show and quite a scare. But as it turns out new data collected from NASA's satellites on the night of the event show that the best view may have in fact been from the red planet itself.
Though often thought of as pristine as they make their first pass through the solar system, keeping their stellar dust intact, the comet bombarded the Martian sky with thousands of unexpected balls of comet dust that warped the outer atmosphere, and gave it a tinge of a yellow afterglow, lasting hours after the comet had come and passed.
Rich in magnesium, iron, sodium, and five other trace metals, the cosmic dust that bombarded Mars may have been heavy enough that researchers like Nick Schneider from the University of Colorado are suggesting it may have not been a meteor shower, but rather a meteor storm. Spiking magnesium deposited in the atmosphere around Mars altered its shape and chemistry, Schneider says. And traces of sodium left the eerie yellow glow after the showers finished.
"It would have been truly stunning to the human eye" Schneider says.
But in spite of not having eyes and ears on the surface of Mars yet, though an achievement already in the works, NASA's and the ESA's orbiting spacecrafts that keep an eye on Mars have been able to learn a lot about the passing comet and changing atmospheres in the process. Causing such a dynamic shift in the composition of Mars' outer atmosphere, the researchers hope is to not only observe the immediate changes, but also see the long-term effects that the comet dust will have on that same region of the atmosphere in the years to come.
It was a strange and rare occurrence, unlike what researchers expected. And while they are excited to have a new venture to focus on in observing the red planet, they are equally thankful that Siding Spring did not pass by here.
"This historic event allowed us to observe the details of this fast moving Oort Cloud comet in a way never before possible, using our existing Mars missions" director of NASA's Planetary Science Division, Jim Green says. "Instead of going to the comet, it came to us."
