Scientists at NASA are hoping to solve a fundamental mystery about Mars’ atmosphere, and you can help. They’ve organized a project called Cloudspotting on Mars, in which the public is invited to identify Martian clouds via the citizen science platform Zooniverse. The data could help researchers figure out why the planet’s atmosphere is only 1% as dense as Earth’s, despite evidence that the planet once had a much thicker atmosphere.
Because the air pressure is so low, liquid water simply evaporates from the planet’s surface and enters the atmosphere. However, lakes and rivers covered Mars billions of years ago, implying that the atmosphere was thicker back then.
How did Mars’ atmosphere deteriorate over time? According to one theory, various mechanisms could be lofting water high into the atmosphere, where solar radiation breaks down the water molecules into hydrogen and oxygen (water is made of two hydrogen atoms and one oxygen atom). Because hydrogen is so light, it could float away into space.
Mars, like Earth, has clouds made of water and ice. However, unlike Earth, it also has clouds made of carbon dioxide (think dry ice), which form when the Martian atmosphere freezes locally. Scientists hope to gain a better understanding of the structure of Mars’ middle atmosphere, which ranges in altitude from 30 to 50 miles (50 to 80 kilometers).
“We want to know what causes clouds to form—particularly water ice clouds, which could teach us how much water vapour is in the atmosphere—and when,” said Marek Slipski, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory in Southern California.
This is where Cloudspotting on Mars comes into play. The project is based on a 16-year archive of data from NASA’s Mars Reconnaissance Orbiter (MRO), which has been studying Mars since 2006. The Mars Climate Sounder instrument on the spacecraft studies the atmosphere in infrared light, which is invisible to the human eye. Clouds appear as arches in measurements taken by the instrument as the MRO orbits Mars. The team needs assistance sifting through the data on Zooniverse and marking the arches so that the scientists can more efficiently study where they occur in the atmosphere.
“We now have over 16 years of data to search through, which is very valuable—it allows us to see how temperatures and clouds change over different seasons and from year to year,” said Armin Kleinboehl, JPL’s deputy principal investigator for Mars Climate Sounder. “However, there is a lot of data for a small team to sort through.”
While scientists have experimented with algorithms to identify the arches in Mars Climate Sounder data, humans can spot them much more easily. However, Kleinboehl believes the Cloudspotting project will help train better algorithms that can do this work in the future. In addition, the project will hold webinars on occasion where participants can hear from scientists about how the data will be used.