scholarly journals The Population of Near-Earth Asteroids in Coorbital Motion with the Earth

Icarus ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 1-9 ◽  
Author(s):  
M Morais
Keyword(s):  
The Earth ◽  
Near Earth Asteroids

Statistical results on discovered near-Earth asteroids

1999 ◽  
Vol 173 ◽  
pp. 81-86
Author(s):  
S. Berinde
Keyword(s):  
Dynamical Evolution ◽  
Minor Planet ◽  
Orbital Elements ◽  
The Earth ◽  
Near Earth Asteroids ◽  
Statistical Results

AbstractThe first part of this paper gives a recent overview (until July 1st, 1998) of the Near-Earth Asteroids (NEAs) database stored at Minor Planet Center. Some statistical interpretations point out strong observational biases in the population of discovered NEAs, due to the preferential discoveries, depending on the objects’ distances and sizes. It is known that many newly discovered NEAs have no accurately determinated orbits because of the lack of observations. Consequently, it is hard to speak about future encounters and collisions with the Earth in terms of mutual distances between bodies. Because the dynamical evolution of asteroids’ orbits is less sensitive to the improvement of their orbital elements, we introduced a new subclass of NEAs named Earth-encounter asteroids in order to describe more reliably the potentially dangerous bodies as impactors with the Earth. So, we pay attention at those asteroids having an encounter between their orbits and that of the Earth within 100 years, trying to classify these encounters.

scholarly journals New Tools for the Optimized Follow-Up of Imminent Impactors

Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 10
Author(s):  
Maddalena Mochi ◽  
Giacomo Tommei
Keyword(s):  
Orbit Determination ◽  
Main Belt ◽  
Impact Monitoring ◽  
The Earth ◽  
Current Observation ◽  
Short Period ◽  
Fly Eye ◽  
Near Earth Asteroids ◽  
Near Earth Objects

The solar system is populated with, other than planets, a wide variety of minor bodies, the majority of which are represented by asteroids. Most of their orbits are comprised of those between Mars and Jupiter, thus forming a population named Main Belt. However, some asteroids can run on trajectories that come close to, or even intersect, the orbit of the Earth. These objects are known as Near Earth Asteroids (NEAs) or Near Earth Objects (NEOs) and may entail a risk of collision with our planet. Predicting the occurrence of such collisions as early as possible is the task of Impact Monitoring (IM). Dedicated algorithms are in charge of orbit determination and risk assessment for any detected NEO, but their efficiency is limited in cases in which the object has been observed for a short period of time, as is the case with newly discovered asteroids and, more worryingly, imminent impactors: objects due to hit the Earth, detected only a few days or hours in advance of impacts. This timespan might be too short to take any effective safety countermeasure. For this reason, a necessary improvement of current observation capabilities is underway through the construction of dedicated telescopes, e.g., the NEO Survey Telescope (NEOSTEL), also known as “Fly-Eye”. Thanks to these developments, the number of discovered NEOs and, consequently, imminent impactors detected per year, is expected to increase, thus requiring an improvement of the methods and algorithms used to handle such cases. In this paper we present two new tools, based on the Admissible Region (AR) concept, dedicated to the observers, aiming to facilitate the planning of follow-up observations of NEOs by rapidly assessing the possibility of them being imminent impactors and the remaining visibility time from any given station.

scholarly journals The partial banana mapping: a robust linear method for impact probability estimation

2019 ◽  
Vol 492 (3) ◽  
pp. 4546-4552
Author(s):  
Dmitrii E Vavilov
Keyword(s):  
Coordinate System ◽  
Confidence Region ◽  
Linear Method ◽  
Probability Estimation ◽  
Curvilinear Coordinate System ◽  
The Earth ◽  
Curvilinear Coordinate ◽  
Near Earth Asteroids ◽  
The Impact ◽  
Confidence Ellipsoid

ABSTRACT This paper presents a robust linear method for impact probability estimation of near-Earth asteroids with the Earth. This method is a significantly modified and improved method, which uses a special curvilinear coordinate system associated with the nominal orbit of an asteroid. One of the coordinates of this system is the mean anomaly in the osculating orbit of an asteroid. A normal distribution of errors of coordinates and velocities of this system is assumed. Because of the usage of the curvilinear coordinate system, the fact that the confidence region is curved and stretched mainly along the nominal asteroid orbit is taken into account. On the main axis of the curvilinear confidence ellipsoid the virtual asteroid, which is the closest to the Earth, is found. The part of the curvilinear confidence ellipsoid, around the found virtual asteroid, is obtained and mapped on to its target plane. The impact probability is calculated as the probability of the asteroid being in the region of the found virtual asteroid multiplied by the probability of a collision of the found virtual asteroid with the Earth. This approach is shown to give more accurate and trustworthy results than the target plane method.

The problem of the near-earth asteroids encountering the earth

2000 ◽  
Vol 43 (10) ◽  
pp. 1114-1120 ◽  
Author(s):  
Ji Jianghui ◽  
Liu Lin
Keyword(s):  
The Earth ◽  
Near Earth Asteroids

scholarly journals Direct and indirect capture of near-Earth asteroids in the Earth–Moon system

2017 ◽  
Vol 129 (1-2) ◽  
pp. 57-88 ◽  
Author(s):  
Minghu Tan ◽  
Colin McInnes ◽  
Matteo Ceriotti
Keyword(s):  
Moon System ◽  
The Earth ◽  
Near Earth Asteroids

The long-term evolution of the main asteroidal belt and the origin of large Mars- and Earth-crossers

1999 ◽  
Vol 173 ◽  
pp. 321-323
Author(s):  
D. Nesvorný ◽  
A. Morbidelli
Keyword(s):  
Numerical Simulations ◽  
Time Scales ◽  
Main Belt ◽  
Subsequent Evolution ◽  
Chaotic Process ◽  
The Earth ◽  
Term Evolution ◽  
Asteroidal Belt ◽  
Near Earth Asteroids

AbstractResults of numerical simulations show that the orbits of asteroids in the inner part of the main belt may gradually, subject to a chaotic process acting on 10-100 Myr time scales, become more elliptic and start intersecting the orbit of Mars. The subsequent evolution of an asteroid having close encounters with Mars frequently leads to the Earth-crossing orbit. This revolutionary scenario of the origin of near-Earth asteroids was quantified by Miglioriniet al.(1998) and here we discuss some of the aspects of this work.

Twentieth-Century Rumblings

Impact! ◽  
1996 ◽  
Author(s):  
Gerrit L. Verschuur
Keyword(s):  
Twentieth Century ◽  
First Century ◽  
Close Encounter ◽  
The Sun ◽  
Infinite Space ◽  
The Past ◽  
The Earth ◽  
Full Circle ◽  
The World ◽  
Near Earth Asteroids

During the first century B.C., Lucretius wrote, “Legend tells of one occasion when fire got the upper hand. The victory of fire when the earth felt its withering blast, occurred when the galloping steeds that draw the chariot of the sun swept Phaeton from the true course right out of the zone of the ether and far over all lands.” He knew about comets, which is why he said, “There is no lack of external bodies to rally out of infinite space and blast [the world] with a turbulent tornado or inflict some other mortal disaster.” This awareness made him think that the world was newly made, and perhaps in some sense it is. The wheel has come full circle. We now appreciate that the threat of comets and asteroids is real, although the distinction between comets and asteroids has grown blurred. What is no longer in doubt is that catastrophic impacts have occurred in the past, and that they will happen again. At the same time, the hypothesis that impacts and flood legends are related is beginning to experience a revival. A chink in the dam of prejudice against the idea actually began to appear in the 1940’s when two astronomers, Fletcher Watson and Ralph Baldwin, in separate books considered the implications of the discovery of near-earth asteroids (NEAs) and concluded that impacts were likely every million years or so. They were all but ignored. In 1942 H. H. Nininger, the famous meteorite researcher, gave a talk to the Society for Research on Meteorites entitled “Cataclysm and Evolution.” Because of his highly specialized forum, his remarks also went unheard in the wider astronomical community. He considered the danger following the close encounter with Hermes, the NEA discovered in October 1937 that passed within 670,000 kilometers of our planet, which can be compared with the moon’s distance of 384,000 kilometers. (Oddly, Hermes has never been found again. Its rediscovery is one of the prizes that asteroid hunters strive for.) If, instead, it had “smacked the earth in a single lump,” the consequences would “constitute a catastrophe of a magnitude never yet witnessed by man,” said Nininger.

5. The threat from space

2014 ◽  
pp. 88-109
Author(s):  
Bill McGuire
Keyword(s):  
Circular Orbits ◽  
Asteroid Impact ◽  
The Earth ◽  
The Future ◽  
Near Earth Asteroids ◽  
Earth Potential ◽  
Asteroids And Comets

‘The Threat from Space’ considers the threat of asteroids and comets colliding with Earth. Potential impacts of Near Earth Asteroids, with almost circular orbits, have been identified, but the threat from comets, which follow strongly elliptical paths, is uncertain. The Mexican asteroid impact 65 million years ago is thought to have wiped out two-thirds of all species living at the time. The Earth will be hit again at some point in the future, but how will it affect us? This will depend upon three things: the size of the object, how quickly it is travelling, and whether it hits the land or the ocean.

scholarly journals The Near Earth Asteroid associations

2012 ◽  
Vol 10 (H16) ◽  
pp. 474-475 ◽  
Author(s):  
Tadeusz J. Jopek
Keyword(s):  
Cluster Analysis ◽  
Analysis Approach ◽  
Earth Asteroid ◽  
Extensive Search ◽  
The Earth ◽  
Near Earth Asteroids

AbstractWe have made an extensive search for grouping amongst the near Earth asteroids (NEAs). We used two D- functions and rigorous cluster analysis approach. We have found several new groups (associations) among the NEAs: the objects moving on similar orbits with small minimum orbital intersection distances (MOID) with the Earth trajectory. Reliability of some of these groups is quite high.

scholarly journals Active bodies in the near-Earth region: The tenuous boundary between comets and asteroids

2015 ◽  
Vol 10 (S318) ◽  
pp. 142-143
Author(s):  
Julio A. Fernández ◽  
Andrea Sosa
Keyword(s):  
Dynamical Evolution ◽  
The Other ◽  
General Definition ◽  
The Sun ◽  
Main Belt ◽  
Close Encounters ◽  
The Earth ◽  
Bare Nucleus ◽  
Short Period ◽  
Near Earth Asteroids

AbstractWe analyze the dynamics and activity observed in bodies approaching the Earth (perihelion distancesq< 1.3 au) in short-period orbits (P< 20 yr), which essentially are near-Earth Jupiter Family Comets (NEJFCs) and near-Earth asteroids (NEAs). In the general definition, comets are “active”, i.e. they show some coma, while asteroids are “inactive”, i.e. they only show a bare nucleus. Besides their activity, NEJFCs are distinguished from NEAs by their dynamical evolution: NEJFCs move on unstable orbits subject to frequent close encounters with Jupiter, whereas NEA orbits are much more stable and tend to avoid close encounters with Jupiter. However, some JFCs are found to move on stable, asteroidal-type orbits, so the question arises if these objects are asteroids that have become active, perhaps upon approach to the Sun. In this sense they may be regarded as the counterparts of the main-belt comets (Hsieh & Jewitt 2006). On the other hand, some seemingly inert NEAs move on unstable, comet-type orbits, so the question about what is a comet and what is an asteroid has become increasingly complex.

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