The bus-size Upper Atmosphere Research Satellite, or UARS, will likely plummet down to Earth sometime around Friday (Sept. 23), according to NASA's latest projections. There is a 1-in-3,200 chance that UARS debris could hit a person, though NASA considers that scenario extremely remote.

"Re-entry is expected Sept. 23, plus or minus a day," NASA officials wrote in an update posted Sunday (Sept. 18). That means that by Saturday (Sept. 24), the UARS satellite should slam into Earth's atmosphere and break apart.