It’s true, Mars just had what we call a Meteor Storm. This is an event that, on Earth, only happens once every few hundred years, and the one that Mars just had was more intense than anything Earth has experienced in recorded history.
This event happened because of a close Martian fly-by of comet C/2013 A1 Sliding Spring. On October 19th around 2:30pm EDT the comet came within 140,000 Km of Mars. This is incredibly close in Astronomical terms, being less than half the distance to the Moon and comparable to the total distance I’ve driven my car in the last four years.
As the comet travels through the solar system, energy from the Sun blasts away at the comet’s icy-dusty surface, liberating hundreds of tons of gas and dust each day. Sunlight also reflects of the streams of material left behind, giving a comet its characteristic tail. When comet Sliding Spring passed by Mars, tons of dust was launched toward the Martian atmosphere, leading to a legendary Meteor Shower.
We would have never known about the shower’s intensity and its effects on Mars, except that NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) and Mars Reconnaisaince Orbiter (MRO) missions were orbiting Mars during the flyby. The European Space Agency (ESA) also had their Mars Express Spacecraft in orbit. All three spacecraft were able to observe the effects of the flyby without being in harm’s way. This is the first time direct observations of an Oort cloud comet have ever been made.
MAVEN was able to detect intense ultraviolet emission from Magnesium and Iron ions in the atmosphere, stronger than any previously detected on Earth. MAVEN was also able to sample some of the comet’s dust, revealing that its composed of at least eight different metal Ions, including sodium, Magnesium, and Iron. MRO saw a huge increase in the electron density in the Ionosphere, likely due to the vaporization of dust in the atmosphere. MRO studied the comet itself, revealing that the nucleus was smaller than the 2 Km that was theorized. It also found that the comet has a rotation period of 8 hours, in agreement with earlier results from the Hubble Space Telescope.
“They call this comet encounter a once-in-a-lifetime event, but it’s more like once-in-a-million years,” said CU-Boulder Associate Professor Nick Schneider, a LASP research associate and lead IUVS scientist for the mission. “MAVEN got there just in time, and we were ready. The numbers suggest a Martian would have seen many thousands of shooting stars per hour — possibly enough to be called a meteor storm — so it must have been a spectacular event that night on Mars.”
The preliminary results from the NASA and ESA spacecraft are spectacular, and they will continue to study the long term effects of the comet’s flyby on the Martian Atmosphere. This was truly the greatest meteor shower humanity has observed in the history of the Universe.
….And nobody was there to watch it.