How satellites die

We were having a chat about data sources new and old, and EO-1 was mentioned. E0_1 has been a very long lived satellite testing hyper-spectral observations (with a remarkably good Irish coverage, especially Munster) but has recently been decommissioned.

We wondered how a satellite thats been orbiting for so much longer than intended is handle at the end of its life (boosted into a higher orbit? Accelerated De-orbited ? Managed de-orbit?)

Anyway we searched around and came up with the end of life program. And this little nugget from the document caught my eye:

 

“7.0       Assessment of Spacecraft Reentry Hazards

To access the risk of human casualty from surviving debris, the total debris casualty area, Da, has been calculated to be 5.9 m2 and the total average population density Pd, for the EO-1 orbit inclination of 98.2° and re-entry year of 2043, is determined to be 12.838 per square km based on information provided by the NASA Orbital Debris Program Office at JSC.  In accordance with the NASA-STD 8719.14, the resulting risk of human casualty from surviving debris is calculated to be 0.0000757 (0.757:10,000) which is within the requirement of less than 0.0001 (1:10,000)

I wonder how a 10,000 to one chance of injury was set as an acceptable threshold

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