Are they called lure floats? It's been so long I've forgotten. Those red-and-white spheres you stick on the end of your fishing line to hold up... bah, nevermind. Anyway A NASA-designed probe is being used to plumb the depths of Antarctica's mysterious Lake Bonnie, an ice-capped body of water in that continent's McMurdo Dry Valleys region. The hope is the lessons learned will help the design of a future Europa probe. Considering this particular analog weighs in at half a ton, it'll probably be awhile before the (presumably) aquatic critters of that moon have to worry about robot probes sent from nosy apes.