On Wednesday, the NASA space probe Cassini performed the first of 22 planned dives through the rings around the planet. No human-made object had ever ventured so far into those swirling bands of ice and dust particles. Cassini was traveling at speeds of 77,000 mph through regions thick with potentially destructive particles. It had to use its dish-shaped antenna as a shield, preventing any communication with Earth during the dive. All day, scientists anxiously awaited confirmation that their brave little space robot had made it through.