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Mysterious Mars plumes stump scientists

Scientists are puzzled by a mysterious plume that erupted off the surface of Mars in 2012. On the right, the location of the plume is identified in the yellow circle. On the left, close-up views of the changing plume morphology in images taken

Mars may not be as dead a planet as we thought. There appears to be a new mystery brewing on Mars that has scientists both puzzled and excited.

On two separate occasions back in 2012, backyard sky-watchers around the world reported seeing through their telescopes what look like gigantic plume-like features rising into space from the surface of the Red Planet. Our current understanding of the high atmosphere of Mars cannot account for this phenomenon. These unknown plumes could also pose a hazard for future low-orbit missions to Mars.

The plumes or strange, blurry clouds were observed to rise to altitudes of more than 250 km above the same region of Mars on both occasions. Adding to the mystery, the features developed in less than 10 hours and could be seen for up to 10 days, changing shape over the course of that time.

“At about 250 km, the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected,” said Agustin Sanchez-Lavega of the Universidad del País Vasco in Spain, lead author of the paper reporting the results in the journal Nature.

While both spacecraft and amateur astronomers have spotted clouds rising in the thin Martian atmosphere many times in the past, what makes these events so unusual is how high these bizarre features appear to be rising off the planet’s surface. Made of dust and ice, clouds seen before these new observations have never before risen beyond 100 km altitude.

To find more clues, astronomers quickly decided to put our best Earth-based instrument, the Hubble Space Telescope, on the case and combed through many years of archived images acquired of Mars. Only the occasional clouds rising to the 100 km mark were seen, except for one set of images from May 1997 that showed an event similar to what the amateurs in 2012 observed.

Now astronomers are trying to piece the puzzle together and working on theories related to high-altitude weather-related events like these seen in the southern hemisphere of the planet.

“One idea we’ve discussed is that the features are caused by a reflective cloud of water-ice, carbon dioxide-ice or dust particles, but this would require exceptional deviations from standard atmospheric circulation models to explain cloud formations at such high altitudes,” said Agustin in a press statement.

“Another idea is that they are related to an auroral emission, and indeed auroras have been previously observed at these locations, linked to a known region on the surface where there is a large anomaly in the crustal magnetic field,” added Antonio Garcia Munoz, a research fellow at ESA’s ESTEC and co-author of the study.

At this point astronomers think it will be a matter of luck. They are crossing their fingers that the Martian phenomenon reappears and one of the satellites currently circling the planet can catch it in action. The trick will be for the orbiter to be at the right place at the right time to see the plume rising.

So this cosmic mystery may remain just that for a while to come.