The orbit of asteroid (99942) Apophis as determined from optical and radar observations

Vinogradova, T. A.; Kochetova, O. M.; Chernetenko, Yu. A.; Shor, V. A.; Yagudina, E. I.

doi:10.1134/s0038094608040011

Cited by 6 publications

(4 citation statements)

References 5 publications

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“…To compare our solutions with the analogous results in the literature, we also determined the nominal orbital elements of model E for the epochs given by Giorgini et al (2008), Vinogradova et al (2008) and two well‐known Web sources: the JPL Small‐Body Data base and Near Earth Objects – Dynamic Site (NEODyS) (see Table 3). In all these four sources the 7 radar measurements have been incorporated into the orbital determinations.…”

Section: Selection and Weighting Of Astrometric Observationsmentioning

confidence: 99%

How selection and weighting of astrometric observations influence the impact probability. The case of asteroid (99942) Apophis

Królikowska¹,

Sitarski²,

Sołtan³

2009

Monthly Notices of the Royal Astronomical Society

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The aim of this paper is to show that in the case of a low probability of asteroid collision with the Earth, the appropriate selection and weighting of the data are crucial for the impact investigation and for analysing the impact possibilities using extensive numerical simulations. By means of the Monte Carlo special method, a large number of ‘clone’ orbits have been generated. A full range of orbital elements in the six‐dimensional parameter space, that is, in the entire confidence region allowed by the observational material, has been examined. On the basis of 1000 astrometric observations of (99942) Apophis, the best solutions for the geocentric encounter distance of 6.065 ± 0.081 R⊕ (without perturbations by asteroids) or 6.064 ± 0.095 R⊕ (including perturbations by the four largest asteroids) were derived for the close encounter with the Earth on 2029 April 13. The present uncertainties allow for special configurations (‘keyholes’) during this encounter that may lead to very close encounters in future approaches of Apophis. Two groups of keyholes are connected with the close encounter with the Earth in 2036 (within the minimal distance of 5.7736−5.7763 R⊕ on 2029 April 13) and 2037 (within the minimal distance of 6.3359–6.3488 R⊕). The nominal orbits for our most accurate models run almost exactly in the middle of these two impact keyhole groups. A very small keyhole for the impact in 2076 has been found between these groups at the minimal distance of 5.97347 R⊕. This keyhole is close to the nominal orbit. The present observations are not sufficiently accurate to eliminate definitely the possibility of impact with the Earth in 2036 and for many years after.

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Section: Selection and Weighting Of Astrometric Observationsmentioning

confidence: 99%

How selection and weighting of astrometric observations influence the impact probability. The case of asteroid (99942) Apophis

Królikowska¹,

Sitarski²,

Sołtan³

2009

Monthly Notices of the Royal Astronomical Society

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“…Obviously, in developing methods to prevent a collision in 2036, these events must be taken into consideration despite their low probability. The estimates for the probability of a collision of Apophis with the Earth are very sensi tive to initial data, as is shown in (Vinogradova et al, 2008;Kochetova et al, 2009;Shor et al, 2012) and, therefore, exhibit a large spread. Shor et al (2012) analyzed the results of the latest refinements of Apo phis' orbit based on the most complete set of observa tional data.…”

Section: Introductionmentioning

confidence: 91%

“…Currently, the condi tions for observations of Apophis are unfavorable (Chesley, 2006;Harris, 2006). The accuracy of its orbit is analyzed, in particular, in the works of Russian authors (Yagudin and Shor, 2005, Vinogradova et al, 2008Kochetova et al, 2009;Shor et al, 2012). The research on the possible strategies for deflecting the asteroid's orbit shows that deflection efforts may be effective only if they are made well in advance of the 2029 approach (see, e.g., Sokolov et al, 2008a).…”

Section: Introductionmentioning

confidence: 99%

Impact trajectories of the asteroid Apophis in the 21st century

et al. 2012

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The asteroid Apophis is one of the most hazardous near Earth asteroids. As a result of the scatter ing of Apophis' potential trajectories after its close approach in 2029, and its possible approach in 2036, there are many dangerous trajectories including impact trajectories after 2036. The purpose of this study is to iden tify and investigate these trajectories. We use the Everhart integrator; the DE405, DE423, and EPM2008 eph emerides; and two sets of initial data for Apophis (those collected by NASA in 2006 and by the IAA in 2010). More than 50 possible encounters in this century are presented, including 13 encounters between 2036 and 2050. The minimum geocentric distances obtained using a different ephemeris and initial conditions differ little between themselves. Analogous results in (Yeomans et al., 2009) are consistent with our results.

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“…The solution NEODyS can be found at http://newton.dm.unipi.it/neodys/ index.php?pc=1.1.0&n=99942. As for our new solu tions, they have been obtained, as well as earlier ones (Vinogradova et al, 2008;Kochetova et al, 2009), by numerical integration of relativistic equations of motion of the asteroid and comparison of calculated positions with observations. During integration, per turbations from all major planets according to the DE 405 ephemeris (perturbations from the Earth and the Moon considering separately), Ceres, Pallas, and Vesta were taken into account.…”

Section: Introductionmentioning

confidence: 99%

On the impact of the Yarkovsky effect on Apophis’ orbit

et al. 2012

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In October 2009, a new set of optical observations of Apophis, a potentially hazardous asteroid, was published. These data have significantly expanded the interval of observations and their total number. In the article we compare the results of refinement of Apophis' orbit made at the Jet Propulsion Laboratory (JPL, United States), the University of Pisa (Italy), and the Institute of Applied Astronomy (IAA) of the Rus sian Academy of Sciences with consideration for new observations. New orbits lead to a significant decrease in the probability of Apophis' collision with the Earth in 2036. As a result of processing a large number of observations of asteroids approaching the Earth and main belt asteroids less than 40 km in size, with a large number of optical and, in many cases, radar observations in different oppositions, one of the authors revealed that additional acceleration affects their motion. This acceleration can be represented by the transversal com ponent A 2 in the orbital coordinate system. The presence of this acceleration can be interpreted as the Yark ovsky effect. The statistical properties of distribution of A 2 for asteroids, for which it is determined quite reli ably, evidence in favor of this interpretation. The value of additional acceleration for bodies the size of Apo phis falls in the range ±10 -13 AU/day 2 . In this paper we have calculated the probability of Apophis colliding with the Earth in 2036 at different values of the transversal component of additional acceleration A 2 . For the resulting points, a plot of the probability of the collision against the A 2 value has been constructed. At A 2 = -8.748 × 10 -14 AU/day 2 (and zero values of the radial A 1 and normal A 3 components) the nominal solution for Apophis' orbit on April 13, 2029, is only 90 m from the middle of a "keyhole" 600 m in width, which leads to a collision of Apophis with the Earth in 2036. Since the scattering ellipse in the target plane in 2029 significantly overlaps the keyhole, the probability of collision at the given additional acceleration value is 0.0022. This result has been verified by the Monte Carlo method. Tests of 10000 random sets of orbital elements, which were found taking into account their correlation, have shown that 22 cases have resulted in virtual asteroids colliding with Earth in 2036. A plot of the probability of the collision against the value of A 2 has been constructed.

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The orbit of asteroid (99942) Apophis as determined from optical and radar observations

Cited by 6 publications

References 5 publications

How selection and weighting of astrometric observations influence the impact probability. The case of asteroid (99942) Apophis

How selection and weighting of astrometric observations influence the impact probability. The case of asteroid (99942) Apophis

Impact trajectories of the asteroid Apophis in the 21st century

On the impact of the Yarkovsky effect on Apophis’ orbit

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