­Hypervelocity Air­­burst Shower Formation of the Pica Glass, Atacama Desert, Chile

The recently discovered Pica Glass in the Atacama Desert, Chile requires rapid heating and quenching of surface materials by multiple airburst fireballs. The most likely scenario involves cascading fragmentation of a comet that broke up upon low-angle entry into the atmosphere. Modeled low-altitude airbursts from six fragments of a single 120-m diameter comet generated separate airbursts in roughly aligned and discrete glass sites that spanned more than 70 km. This scenario is not a unique solution; there are tradeoffs among speed, size, strength, and height of burst. The Pica Glass, because of its young age, provides useful ground truth for airburst simulations in support of planetary defense risk assessment.

Computational shock physics models demonstrate that multiple discrete low-altitude airbursts from a small comet that fragmented upon low-angle entry into the atmosphere is compatible with the distribution and extent of the Pica Glass. Such a scenario has a sufficiently high probability that it is compatible with the young age of the glass, and is also relevant to airburst risk assessment for planetary defense.