After 19 eventful years, both for astronomy and for itself, NASA has finally said goodbye to the Hubble Space Telescope.Early Tuesday morning, space shuttle Atlantis astronauts undocked the telescope from the shuttle's cargo bay.Mission Specialist Megan McArthur held on with the robotic arm as the orbiting observatory gently drifted away.When it reached an optimal distance at 8:57 a.m. EDT,