SUMMARY

SUMMARY

This event was a satellite de-orbit that occurred at 01:15 AM local time on 11 October 2018, or 08:15 11 Oct 2018 UTC. The fireball moved slowly across the sky, visibly shedding a large number of smaller pieces. This behavior is consistent with a space debris re-entry rather than the fast-moving, short-lived event produced by a meteor. 30 eyewitnesses reported it to the American Meteor Society across California. Two eyewitnesses reported hearing sonic booms from the falling debris.

At least one piece of the satellite has been recovered from this event and was reported in local media (opens in a new window):

https://www.fresnobee.com/news/local/article220259570.html

This event is recorded as American Meteor Society event number 4094 for 2018. Signatures of falling meteorites can be found in imagery from four nearby weather radars. In the NEXRAD weather radar network operated by NOAA, the KHNX (San Joaquin Valley, CA), KVBX (Vandenburg AFB, CA), KEYX (Edwards, CA), and KVTX (Los Angeles, CA) radars record signatures of falling debris.

While it is possible to calculate the mass of falling meteorites seen in weather radar data, it is currently not possible to perform the same calculation for falling satellite debris. This is because meteorites are fairly homogenous – they are composed of a single type of material and have pretty much the same shape. Satellite debris is composed of materials ranging from metals to lightweight insulation, and come in all manner of shapes – spheres, rods, pieces of fabric, etc. Because radar does not tell us what type or shape each piece is, we cannot calculate its mass at present. Debris falls tend to cover a much longer fall area, however, because satellites move much slower than meteors and usually enter the atmosphere at a very flat trajectory. The ground path of this debris fall is almost 200 km long, and larger material quite likely landed farther north, according to eyewitness accounts. By comparison, most meteorite falls are only about 10 or 20 km in length.

The Orbital Debris Office here at NASA Johnson Space Center studies material and events like the one depicted here, in order to understand the threat posed to spacecraft and astronauts by orbital debris.  To learn more, have a look at their website: https://www.orbitaldebris.jsc.nasa.gov/