Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Physics

Supervisor

Peter Brown

Abstract

The goal of this thesis is to better understand the physical and chemical properties of meteoroids by using simultaneous radar and video observations of meteors. The Canadian Meteor Orbit Radar (CMOR) and several Gen-III image-intensified CCD cameras were used to measure common meteors and validate metric errors determined through Monte Carlo modelling and to relate radar electron line density (q) to video photon radiant power (I). By adopting an ionisation coefficient from Jones (1997) and using recorded measurements of q/I, a corresponding estimate of the fraction of meteoroid kinetic energy loss converted into light (luminous efficiency) was found.

It was found that 7% ± 3% of video meteors were also simultaneously detected as specular echoes by radar, larger than the expected 2% − 5% from modelling. Errors in the fiducial picks for video meteors were found to be anisotropic, with video speeds being higher on average compared to radar speeds, consistent with more deceleration in specular radar measurements. Most radar detections occurred near the end of their meteor trails, suggesting simultaneous observations are biased towards larger, non-fragmenting meteoroids. The peak luminous efficiency was found to be 5.9% at 41 km/s. The magnitude scale and electron line density were found to relate as M = (38.7 ± 1.2) − 2.5 log10 q.

These results suggest the masses of higher speed meteoroids are an order of magnitude smaller than previously thought, implying the total meteoroid mass influx for small meteoroids is below earlier estimates. The main uncertainties associated with this analysis are the unknown spectra of individual meteors (which affects estimates of I), and assumptions of the initial meteor trail radius (which affects estimates of q). To improve future simultaneous comparisons, an automated video meteor observatory was constructed. This system, named the Canadian Automated Meteor Observatory (CAMO), features a guided camera which tracks meteors in real-time, giving higher precision video measurements of deceleration and fragmentation for comparison to radar measurements. CAMO can also be used to constrain numerical meteoroid ablation models and to measure the meteoroid mass in-flux at Earth.


Included in

Other Physics Commons

Share

COinS