Are meteoroids really dustballs?

Analysis of light curves of faint meteors seem to suggest that most meteoroids are collections of hundreds to thousands of fundamental grains at least some of which are released prior to the onset of intensive ablation. We would expect these grains, unless extremely uniform in physical properties, to be aerodynamically separated during flight, and therefore to produce wake, which is defined as instantaneous meteor light production from an extended spatial region. We present here theoretical results for wake production as a function of grain mass distribution, height of separation, zenith angle and velocity. In addition, we have obtained observational results from a new study which used short duration intensified CCD detectors to search for wake in sporadic meteors. The system employed coaxial intensified CCD cameras at each of two separated stations, one camera utilizing a rotating shutter and one not at each station. The majority of these nonshower meteors showed no statistically significant wake. However, several examples of apparent transverse separation of the light production regions were found. We also present results of two interesting Leonid meteors from the Mount Allison light curve experiment in NASAʹs 1998 Leonid Multi-instrument Aircraft Campaign (MAC) program. One of these provide support for the idea of transverse spread in the light production region, up to hundreds of meters, while the other provides a clear case of extreme wake in one Leonid meteor which can only be successfully modeled with very small (≈10−16–10−17 kg) constituent grains.