author here. Some cross bedding features could be wind generated (ha! geography!). But theres also a lot of evidence of hydrous minerals - clays, etc - and evidence of frozen ice, especially in the Northern basin of Mars.

Theres a lot of debate about the efficiency of atmospheric stripping and hence water loss. It apparently depends on a lot of modelling assumptions and there's also a fair amount of evidence for water locked up in the cryosphere of Mars. However, what we're saying is that irrespective of atmosphere loss or potential water stores, Mars was doomed from the off by virtue of its mantle chemistry. Liquid water would simply react with its surface rocks, forming dense hydrous minerals which then allows a transport mechanism of water to the mantle. This ain't good for the prospects of the evolution of life on Mars and has implications for life on extra solar planets.

And as a LONG time slashdot botherer (yeah, I've lost my UID more than once....) I'm more than happy to answer questions (if I can!) shit - this is the pinnacle of my science career - SLASHDOT!!!

Its advantages are obvious - each round is cheap, it doesn't get lost and end up as a technology or a munition 'giveaway' (or bad press), and as the article says, reaction time can be rapid. It means that the next class of boats are merely floating powerstations with all the 'goodies' held far away from the action. Besids, a rail gun is not just line of sight, as with any ballistic weapon, unless you can see over the horizon. I guess the main limiting factors in use would be those of ablation - both to the rail and projectile.