Observational constraints on the number, albedos, size, and impact hazards of the near-Earth asteroids

This work provides a statistical description of the near-Earth asteroids (NEAs) in terms of number, orbital parameters, reflectance spectra, albedos, diameters, and terrestrial and lunar collision rates. I estimate the size and shape of the NEA population using survey data from the Lincoln Near-Earth Asteroid Research project including more than 1300 NEA detections. The NEA population is more highly inclined than previously estimated and the total number of NEAs with absolute magnitudes (H) brighter than 18 is 1227 +170/-90. The absolute magnitude and orbital parameter distributions for the NEAs are combined with reflectance spectra and albedo measurements. I obtain a debiased estimate of the fraction of NEAs in each of 10 taxonomic complexes, and a debiased average albedo for each. The number of NEAs larger than 1 km is 1090 +/- 180. Next, I determine the impact frequency, collision velocity distribution and collision energy distribution for impacts of NEAs into the Earth and Moon. Globally destructive collisions ([approx.] 1021 J) of asteroids 1 km or larger strike the Earth once every 0.60 +/- 0.1 Myr on average. Regionally destructive collisions with impact energy greater than 4x1018 J ([approx.] 200 m diameter) strike the Earth every 47,000 +/- 6,000 years. The rate of formation of craters expected from the NEAs is found to be in close agreement with the observed number of craters on the Earth and Moon.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Stuart, Joseph Scott, 1971-

Advisor dc:contributor.advisor

• Richard P. Binzel.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/49805

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/49805