GALCIT Colloquium

Meteoroids and orbital debris, collectively referred to as hypervelocity impactors, travel between 7 and 72 km/s in free space. Upon their impact onto the spacecraft, the energy conversion from kinetic to ionization/vaporization occurs within a very brief timescale and results in a small and dense expanding plasma with a very strong optical flash. The radio frequency (RF) emission produced by this plasma can potentially lead to electrical anomalies within the spacecraft. In addition, space weather, such as solar activity and background plasma, can establish spacecraft conditions which can exaggerate the damages done by these impacts. During the impact, a very strong impact flash will be generated. Through the studying of this emission spectrum of the impact, we hope to study the impact generated gas cloud/plasma properties.

The impact flash generated during a ground-based hypervelocity impact is long expected by many researchers to contain the characteristics of the impact generated plasma, such as plasma temperature and density. In this presentation, we will present possible theories of how hypervelocity impact light flash is generated by the plasma, supported by experiments at a ground-based 2 MV electrostatic dust accelerator using three spectral photomultiplier tubes at 450, 550, and 600 nm. We will also demonstrate the use of Bresstrauhlung/Blackbody emission model to characterize the impact generated plasma, and show some of the latest experimental results directly connect the impact generated plasma and the impact flash.

This lecture is part of the Young Investigators Lecture Series sponsored by the Caltech Division of Engineering and Applied Science