Flashy news from Mars

Early last year, just 2 months after the rover Spirit landed on the Red Planet, the craft recorded a strange streak across the Martian sky. Having analyzed the brightness, timing, and orientation of the streak, researchers now conclude that the event was most likely a meteor associated with a comet called Wiseman-Skiff.

If the scientists are correct, it would be the first time that astronomers have identified a Martian meteor and its parent comet, the researchers report in the June 2 Nature.

Meteor showers occur when a planet intersects the orbit of a comet that regularly visits the inner solar system. Rocks and clumps of dust shed by the comet as it approaches the sun burn up in the planet’s atmosphere, where they appear as streaks. For example, the Leonid meteor shower, which graces the skies over Earth every mid-November, happens when our planet skims the dusty trail of Comet Tempel-Tuttle.

Spirit observed the streak of light on March 4, 2004. That was just 4 days before Mars was predicted to encounter debris from Comet Wiseman-Skiff, note rover scientist Mark T. Lemmon of Texas A&M University in College Station and his colleagues. Other properties of the streak, including its proximity to the horizon, suggest that it was a grazing meteor that passed 200 to 300 kilometers from Spirit.

Observations of additional Martian meteors, the team notes, could reveal the chemical interaction of these vaporized clumps with the Red Planet’s carbon dioxide–rich atmosphere. That, in turn, might shed light on the atmospheric chemistry of the early Earth, which theorists have proposed was unusually rich in carbon dioxide and heavily bombarded by debris from comets and asteroids.

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