NASA's Swift observatory, launched in 2004, is expected to re-enter Earth's atmosphere after an unsuccessful rescue attempt. The telescope, functioning for more than two decades, will break apart during re-entry. Most debris will burn up in the atmosphere. Experts predict the impact zone could cover over 80% of Earth's surface. Authorities are observing the scenario to gauge threats to populated zones. The exact location of impact has not been determined. NASA's Swift Observatory Falling to Earth: Who Is Responsible If Debris Results in Harm?