Wednesday Highlights:

A bit of a quiet day. (actually, I had a shocking hangover, so was glad not to be in full demand),

A young Japanese gentleman called Ishii presented a very familiar CO2 flow model for the modern gullies. I gave him a copy of my paper on the subject!

Alan Trieman then presented a very interesting study of dry granular flows on unstable slopes, showing that one can perhaps bridge the whole spectrum fro m dark slope streaks to dry avalanches to gullies - all with dry flows. Most importantly, he is demolishing the stupid (IMHO) idea that flows are “generated” by fluid escape on an impermeable layer in the wall of craters and canyons. He presented lots of examples of gullies working back up slope from an initiation point in mid-slope and interacting with strong resistant layers. The effect is one of strength, not fluids.

Jeff Kargel put forward a model of Mars as a sulphate and gas-hydrate rich world. He was mobbed by the press afterwards, so you may see an article on this in the next few days. Jeff is an expert on ices in the solar system and his views are always interesting.

Mark Bullock showed that the combination of salts produced by simply soaking basalt in water, under a CO2-rich atmosphere, is quite similar to those found in the soils and dusts of Mars.

Small correction to Derek Sears’ water evaporation studies. The ice forms after 60 minutes, not 10, or whatever I said yesterday!

And two contenders for fun experiments of the year:

Jens Ormo used explosives and bolt guns to generate metre-scale craters in soft sand targets, with an overlying water layer, to study marine impacts. Few conclusions,but great videos!

Ralph Lorenz rigged-up a wave tank inside one of NASA’s giant vacuum chambers. He found that wave height over water decreased with pressure, as expected, but not linearly. Below about 300-400 mbar, wave activity effectively ceased. When he tried to force it by putting extra fans in, the water simply froze over.

He also experimented with kerosene and saw somewhat larger waves. Ralph is working towards understanding ocean waves on Titan, and also supplying data relevant to lakes and oceans on Mars. Most models of post-Noachian Mars don’t exceed a few hundred mbar, so this may explain the lack of beaches, rather than ice cover – the usual explanation.

After all this excitement, I took my hangover back to bed and had the afternoon off – except for booking my next 3 weeks’ worth of flights around Asia. It’s going to be a busy time, so I’ll be in and out of communication, starting tomorrow…