More than 24,400 catalogued orbiting objects have re-entered so far into the Earth's atmosphere since the beginning of the space age. The associated mass, close to 30,000 metric tons, was mainly concentrated in intact objects, i.e. payloads and spent upper stages, accounting for nearly 29% of the re-entered objects. During the 10 years from 2008 to 2017, 448 large (i.e. with a radar cross-section > 1 m2) intact objects, represented by 366 rocket bodies (∼82%) and 82 spacecraft (∼18%), re-entered uncontrolled into the Earth's atmosphere. The corresponding total mass was approximately 911 metric tons, 83% concentrated in upper stages and the remaining 17% in spacecraft. The average re-entered mass per year was approximately 90 metric tons. Objects with a mass greater than 500 kg re-entered, on average, every 9 days, while those with mass above 5000 kg every 215 days.
In about 4% of these re-entries, the casualty expectancy was expected to exceed, by approximately one order of magnitude, the threshold of 10^-4. In almost 84% of the events the casualty expectancy could have been of the order of 10−4. Only in approximately 12% of the cases the casualty expectancy was probably significantly lower than 10−4. Depending on the distribution in inclination and latitudes overflown, it was found that the Italian territory would have been affected in about 77% of the cases and continental Europe in approximately 80% of the events.
About 73% of the objects had a nearly circular orbit just before re-entry, while only 3% re-entered from highly eccentric orbits. 38 objects were sighted re-entering from 2010 to 2018 by eyewitnesses and pieces of debris were retrieved in at least 14 occasions. Among them, only one was linked to a spacecraft (Iridium 70), while all the others were probably components of upper stages.
Reference: Pardini, C. and Anselmo, L., Uncontrolled re-entries of spacecraft and rocket bodies: A statistical overview over the last decade, The Journal of Space Safety Engineering, 6 (2019) 3047, doi: 10.1016/j.jsse.2019.02.001.
Authors
Carmen Pardini (carmen.pardini@isti.cnr.it)
Luciano Anselmo (luciano.anselmo@isti.cnr.it)
Contact point: Carmen Pardini (carmen.pardini@isti.cnr.it)
Acknowledgements
Part of the work was carried out in the framework of the ASI-INAF agreement No. 2015-028-R.0 on "Space Debris: support to IADC activities and pre-operational validation for SST".
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