Largest piece of orbital debris to make an uncontrolled re-entry

The largest object to make an uncontrolled re-entry into Earth's atmosphere was the Skylab space station, which had a mass of 75.7 tonnes (83 US tons) at the time of its re-entry on 11 July 1979.

Skylab was launched atop a Saturn V rocket on 14 May 1973. Its core was a converted S-IVB rocket stage (the third stage of the Saturn V, used for trans-lunar injection burns). As the station was only being deployed to Low Earth Orbit, it was possible to launch the Saturn V with only its lower two stages, replacing the usual third stage with the space station body.

Three crews lived on Skylab for a total of 172 days between 25 May 1973 and 8 February 1974. The program was terminated prior to the launch of the fourth mission due, in part, to the high cost of the Saturn IB rockets used to deliver crew to the station. It was intended for the station to be either reactivated or de-orbited by the Space Shuttle (which was scheduled to enter service in the late 1970s), however, these plans were abandoned when it became clear that the Shuttle would not be ready in time to save the station.

Skylab re-entered Earth's atmosphere on 11 July 1979. NASA controllers had shifted the station's orientation to increase the chances of it burning up on re-entry, but had little control where or when it would come down. The station came down over Western Australia, scattering debris over an area roughly 150 km (93 mi) wide between the towns of Esperance and Rawlinna. No one was hurt, nor property damaged by falling debris, but the Shire of Esperance famously fined NASA $400 for littering.

Other contenders for this record are the 40-tonne Soviet space station Salyut 7, which made a completely unpowered and uncontrolled rentry on 7 February 1991, and the 106.4-tonne Space Shuttle Columbia which went out of control and broke apart mid-way through re-entry on 1 February 2003.