Ablation of Organics from Simulated Micrometeoroids

Micrometeoroids are a source of exogenous material that affects the atmospheres and surfaces of planets. On the Earth, metals from meteoroids affect the chemistry of the upper atmosphere, and organics delivered to the young Earth by meteoroids may have played a role in the origin of life. Furthermore, observations of meteors provide important constraints on the nature of the interplanetary dust environment and its sources. These observations, though, are sensitive to the processes of heating, drag, and ionization that produce plasma and light to make meteors detectable. To study these processes, we use the dust accelerator and gas target facility at the University of Colorado to create simulated meteors in the laboratory. Using this facility, we have studied the ionization, drag, and heating of simulated meteors. We recently shot organic-coated olivine particles into the gas target containing air at 10-20 km/s to constrain the heating and ionization of meteoric organics. The organic coating consisted of polypyrrole (PPy). 16 charge collectors placed in a line inside the gas target collected the charges produced by the particles as they traveled through the target, allowing the charge production by the particles to be resolved as a function of distance. The PPy coating was observed to ablate from the particle, whereas the olivine cores of the particles did not ablate and instead hit an impact detector at the end of the gas target. The results show that the PPy coating can ablate separately from the olivine particle, and the observed charge production allows the ablation products of PPy to be constrained. Charge production was observed even at low velocities, meaning that large molecules with low ionization potentials are probably responsible for producing the collected charges. This indicates that large organic molecules might be surviving ablation from the simulated micrometeoroids. These results show that differential ablation of organics is possible, and since large organics may be surviving that ablation they may influence the organic budget of a planet.