I’m working on a new show about Mars and thus have become a “sink” for Mars info. Humans have a record number of spacecraft at or on the planet right now, and getting images every few days or so from one or the other of them is like having a webcam on the red planet. The latest picture is something of a “weather report,” showing high, thin clouds that are pretty rare at the altitudes they’ve been found over the Martian surface.

What’s the scoop here? Back in 1997, the Mars Pathfinder rover snapped an image of wispy looking clouds at Mars. The big mystery was, since most clouds seemed to be closer to the Martian surface, what were these high fliers and how did they form?

Astronomers using the European Space Agency’s SPICAM instrument (an infrared spectrometer that measures what the clouds do to starlight as it passes through them) actually found a NEW layer of high, thin clouds at Mars. They seem to be made of carbon dioxide crystals that exist 80 to 100 kilometers (50 to 60 miles) up in the already thin carbon-dioxide atmosphere. You can read more details about the SPICAM findings here.

Why the interest in clouds? Although many images we see are of ground formations (craters, dunes, canyons, and volcanoes) on Mars, the atmosphere is an equally important component of the planet. Among other things, if you study the atmosphere for a long-enough time, you can build up a seasonal picture of change in the different atmospheric layers. It’s also important to know atmospheric density, since this affects the entry of spacecraft into the planet’s atmosphere.

I often wonder what future Mars explores will do with all this data we’re collecting today. Surely it will help refine their exploration routes and approaches. I wish we’d get there soon, so I can find out!