spacewatch end rosat if thought nasas odds 3200 earth struck piece falling uars satellite worrying major satellite decay poses risk german aerospace center puts equivalent odds rosat roentgen satellite 2000 fact personal odds hit like 1 14 trillion probably safe away tin live north wash danger zone extends 53â° n rocket 1990 rosat joint venture germany uk equipped 84cm mirror completed x ray survey sky finding 150000 objects followed targeted observations interesting objects galaxies neutron stars comets switched 1999 i calculate weeks away entry orbit decays survive novemberat 2400kg rosat half massive uars half thought likely survive entry including heavy mirror built glass ceramic material high melting point expectation drop harmlessly ocean tracking authorities took days confirm details uarss plunge pacific let hope better rosat