The conservationist in me always cringes whenever I hear of hydrogen or helium gases escaping gravitational pull, because I know it's never coming back. I always have to remind myself that the planets are ultimately doomed anyway, and that there's a ton more gas than I can imagine, so supply is not yet in danger of exhaustion. (that I apply these concerns to another planet I'll probably never even get near, I have decided to simply take in stride)

Nonetheless, cool article. It's interesting how many theories are coming about anymore involving life on satellites rather than planets. I understand they are probably more common than small rocky planets what with the abundance of gas giants, but are they more or less suited to life? It seems like the presence of a massive body nearby (the planet it's orbiting) would have a big impact. Plus, the distance from the sun would increase and decrease (meaning light and temperature variations), and overall incumbent light would be minimal.