Scientists from MIT have discovered microscopic CO2 snowflakes, about the size of a red blood cell, on Mars.
"These are very fine particles, not big flakes," said Kerri Cahoy, the Boeing Career Development Assistant Professor of Aeronautics and Astronautics at the MIT, in a statement. "If the carbon dioxide particles were eventually to fall and settle on the Martian surface, you would probably see it as a fog, because they're so small."
Scientists discovered this when they were analysing data obtained from the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO).
The study also revealed that snow particles in the south were slightly smaller than snow in the north. They claim that the snowflakes in the North Pole were 50 percent larger than the snowflakes found in the South Pole.
Over the course of a Martian year (a protracted 687 days, versus earth's 365), the researchers observed that as it gets colder and darker from fall to winter, snow clouds expand from the planet's poles toward its equator. The snow reaches halfway to the equator before shrinking back toward the poles as winter turns to spring, just like on earth, according to the scientists.
"For the first time, using only spacecraft data, we really revealed this phenomenon on Mars," said Renyu Hu, researcher at the MIT, in a statement.
To know exactly how much CO2 snowflakes had fallen on Mars, scientists had analysed several data taken by the MRO and MGS.
Scientists found that the total mass of snow in the north and south poles in Mars. They found that in the north, molecules of condensed carbon dioxide ranged from 8 to 22 microns, while particles in the south were a smaller 4 to 13 microns.
"It's neat to think that we've had spacecraft on or around Mars for over 10 years, and we have all these great datasets," Cahoy says. "If you put different pieces of them together, you can learn something new just from the data."
Scientists believe that knowing the size of carbon dioxide snow cloud particles on Mars may help researchers understand the properties and behaviour of dust in the planet's atmosphere.
"They could be completely different in their contribution to the energy budget of the planet," Hu said. "These datasets could be used to study many problems," he concluded.