What is the overall risk from reentry debris?

The space station Mir reentered in 2001. Credit: NASA

The overall risk to an individual from reentering debris is extremely small compared to the hazards we face daily. For example, the risk that an individual will be hit and injured by a piece of debris is estimated to be less than one in one trillion. To help understand this, the risk that an individual in the U.S. will be hit by lightning is one in 1.4 million. The chance that an individual in the U.S. will be killed in a hurricane is about one in six million.

The reentry risk predictions are supported by the fact that over the last 40 years, more than 5,400 metric tons of materials are predicted to have survived reentry, with no reported casualties. Of course, it is possible that casualties have occurred somewhere in the world, but have not been reported. The largest object to reenter was the Russian Mir Space Station, which weighed 120,000 kg.

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