Wrapping up items from AGU

I realize it's been a week since I left the American Geophysical Union meeting but there was just so much to cover! Fortunately, even after I left, I received some updates from some friends who were able to attend more of the sessions, and sent me some notes.

Jim Burke, who has a long and distinguished career in space exploration and now serves as technical editor for The Planetary Report, sent me these terse but informative notes on the Mars sessions that took place later last week:

• "Present-day cratering excavates ice at mid-latitudes." In other words, when an impact happens on an area of Mars that's not near the poles (mid-latitudes instead of high latitudes is like the latitudes of the U.S. and Europe instead of the latitude of Devon Island), the crater digs into ice. Cool.
• "Water alteration of minerals shown all over the place." That is, the sharper-eyed orbiters are finding more and more evidence for liquid water having interacted with Mars' rocks to change their original (mostly volcanic) mineral grains into different minerals, such as sulfates, halides, and carbonates.
• "Good progress in many fields regarding polar ice caps, layering, seasonal mass exchange, underlying topography from radar." There's ice at the poles, but how long has it been there? What do the layers mean? How deep is it, how much water does it represent? Scientists are attacking all these questions and making progress, Jim is saying.
• "Landslide fan shapes include some suggestive of sub-lake debris flows." Ooh, this one is cool. There are landslide-type deposits all over Mars -- that's not news. But evidently some people are arguing that the shape of the landslide deposits in some places look like they happened under water.
• "Many weird gully shapes; probably a variety of origins." The more you look at images from all the different orbiters that are now studying, or have studied Mars, the more diversity you see in the landscape. Jim is saying that they don't all have the same genesis. Some could result from dry or cold processes, some from processes that may have needed water. Some could be related to impacts, some to tectonics, some to volcanism. Et cetera.
• "Much progress regarding the atmosphere, global dust events, and the state of the thermosphere." Jim probably has a higher interest in the above-ground stuff than I do...
• "Surface ground truth gave few surprises relative to expectations from orbital data." If I understand this comment correctly, it is great news: it means that orbital reconnaissance is working, that the ground studies are, in general, confirming the hypotheses made on the basis of studies from a distance.

And finally, I'll just mention that little ol' me is the star of this week's Planetary Radio, reporting on the news from AGU. If you've read every word I wrote about the meeting, you won't learn anything particularly new, but if you skimmed my longer entries, it might be worth a listen!