This is a list of artificial objects reentering Earth's atmosphere by mass (see space debris). Such objects are often completely destroyed by reentry heating, but large enough objects or components can survive. Most of the objects which reenter are relatively small; larger objects have survived but usually break up into smaller pieces during reentry.[1][2][3]
The list includes group entries for the 134 Space Shuttle external tanks used between 1981 and 2011. During Space Shuttle launches, the tanks reached space without reaching orbit and re-entered the atmosphere, breaking apart before impacting the ocean. The mass of those tanks varied throughout the years, as improvements made them lighter - successive modifications reduced their empty weight from approximately 77,000 pounds (35,000 kg) to approximately 58,500 lb (26,500 kg) for the Super Lightweight Tank used after 1998.[4] The tanks were also not necessarily completely empty when discarded.[5]
Many other launch systems have discarded spent stages into space, but not all stages go into orbit or even reach space (by passing the Kármán line). For example, the Space Shuttle side boosters did not reach space, as the highest altitude reached during their flight was only about 220,000 feet (67 km).
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