Distribution Of near-Earth Objects Research Articles

NEOMOD 3: The debiased size distribution of Near Earth Objects

Our previous model (NEOMOD2) for the orbital and absolute magnitude distribution of Near Earth Objects (NEOs) was calibrated on the Catalina Sky Survey observations between 2013 and 2022. Here we extend NEOMOD2 to include visible albedo information from the Wide-Field Infrared Survey Explorer. The debiased albedo distribution of NEOs can be approximated by the sum of two Rayleigh distributions with the scale parameters pV,dark≃0.03 and pV,bright≃0.17. We find evidence for smaller NEOs having (on average) higher albedos than larger NEOs; this is likely a consequence of the size-dependent sampling of different main belt sources. These inferences and the absolute magnitude distribution from NEOMOD2 are used to construct the debiased size distribution of NEOs. We estimate 830±60 NEOs with diameters D>1 km and 20,000±2,000 NEOs with D>140 m. The new model, NEOMOD3, is available via the NEOMOD Simulator — an easy-to-operate code that can be used to generate user-defined samples (orbits, sizes and albedos) from the model.

Near-Earth object population and formation of lunar craters during the last billion of years

AbstractWe compared the number of lunar craters with diameters greater than 15 km with age less than 1.1 Gyr in the region of the Oceanus Procellarum with the estimates of the number of craters made based on the number of near-Earth objects and on the characteristic times elapsed before collisions of near-Earth objects with the Moon. Our estimates allow the increase of the number of near-Earth objects after a recent catastrophic disruption of a large main-belt asteroid. However, destruction of some old craters and variations in orbital distribution of near-Earth objects with time could allow that the mean number of near-Earth objects during the last billion years could be close to the present value.

Distribution of the near-earth objects

This paper analyzes the distribution of the orbits of near-Earth minor bodies from the data on more than 7500 objects. The distribution of large near-Earth objects (NEOs) with absolute magnitudes of H < 18 is generally consistent with the earlier predictions (Bottke et al., 2002; Stuart, 2003), although we have revealed a previously undetected maximum in the distribution of perihelion distances q near q = 0.5 AU. The study of the orbital distribution for the entire sample of all detected objects has found new significant features. In particular, the distribution of perihelion longitudes seriously deviates from a homogeneous pattern; its variations are roughly 40% of its mean value. These deviations cannot be stochastic, which is confirmed by the Kolmogorov-Smirnov test with a more than 0.9999 probability. These features can be explained by the dynamic behavior of the minor bodies related to secular resonances with Jupiter. For the objects with H < 18, the variations in the perihelion longitude distribution are not so apparent. By extrapolating the orbital characteristics of the NEOs with H < 18, we have obtained longitudinal, latitudinal, and radial distributions of potentially hazardous objects in a heliocentric ecliptic coordinate frame. The differences in the orbital distributions of objects of different size appear not to be a consequence of observational selection, but could indicate different sources of the NEOs.

Some aspects of the statistics of Near-Earth Objects

AbstractThe distribution of Near-Earth Objects, in particular Near-Earth asteroids is examined using maximum likelihood methods. These are analysed with respect magnitudes, taxonomic classes and to their orbital distances. Comparisons are made with the distributions of main-belt asteroids and short-period comets.

Earth and space-based NEO survey simulations: prospects for achieving the spaceguard goal

We have used an improved model of the orbit and absolute magnitude distribution of Near Earth Objects (NEOs) to simulate the performance of asteroid surveys. Our results support general conclusions of previous studies using preliminary Near Earth Asteroid (NEA) orbit and magnitude distributions and suggest that meeting the Spaceguard Goal of 90% completion for Near Earth Objects (NEOs) greater than 1 km diameter by 2008 is impossible given contemporary surveying capabilities. The NEO model was derived from NEO detections by the Spacewatch Project. For this paper we developed a simulator for the Catalina Sky Survey (CSS) for which we had a complete pointing history and NEO detection efficiency. The good match between the output of the simulator and the actual CSS performance gives confidence that both the NEO model and simulator are correct. Then, in order to determine if existing surveys can meet the Spaceguard Goal, we developed a simulator to mimic the LINEAR survey, for which detailed performance characteristics were unavailable. This simulator serendipitously provided an estimate for the currently undiscovered population of NEOs upon which we base all our estimates of time to 90% completion. We also developed a set of idealized NEO surveys in order to constrain the best possible survey performance in contrast to more realistic systems. A 100% efficient, all-sky, every night survey, subject only to the constraints of detection above a specified air mass and when the Sun is 18° below the horizon provides a benchmark from which to examine the effect of imposing more restrictions and the efficacy of some simple survey strategies. Such a survey must have a limiting V-magnitude of 20.1 ± 0.2 to meet the Spaceguard Goal. More realistic surveys, limited by latitude, the galaxy, minimum rates of NEO motion, etc., require fainter limiting magnitudes to reach the same completion. Our most realistic simulations, which have been normalized to the performance of the LINEAR detector system’s operation in the period 1999–2000, indicate that it would take them another 33 ± 5 years to reach 90% completeness for the larger asteroids (≳1 km diameter). They would need to immediately increase the limiting magnitude to about 24 in order to meet the Spaceguard Goal. The simulations suggest that there may be little need for distributing survey telescopes in longitude and latitude as long as there is sufficient sky coverage from a telescope or network of telescopes which may be geographically close. An idealized space-based survey, especially from a satellite orbit much interior to Earth, would offer an advantage over their terrestrial counterparts. We do not consider a cost–benefit analysis for any of the simulations but suspect that a local-area network of telescopes capable of covering much of the sky in a month to V ∼ 21.5 may be administratively, financially, and scientifically the best compromise for reaching 90% completion of NEOs larger than 1 km diameter.