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, as both shuttle and telescope hovered over North Africa, she let go and the telescope went off on its own, never again to be touched by human hands."Hubble has been released," reported commander Scott Altman. "It's safely back on its journey of exploration as we begin steps to conclude ours. Looking back on this mission, it's been an incredible journey for us as well."