There may be enough oxygen in the waters of Jupiter's moon Europa to support millions of tons worth of fish, according to a new study. And while nobody is suggesting there might actually be fish on Europa, this finding suggests the Jovian satellite could be capable of supporting the kinds of life familiar to us here on Earth, if only in microbial form. Europa, which is roughly the size of Earth's moon, is enveloped by a global ocean about 100 miles deep (160 km), with an icy crust that may be only a few miles thick. From what we know...