The most relevant tasks associated with the problem of asteroid–comet hazard are discussed. A review is given of the respective research at the Institute of Applied Astronomy. The institute is currently implementing a project to create an information center whose tasks include the collection and processing of optical and radar observations of small solar system bodies, determination of their orbits, and assessment of the impact hazard of the newly discovered small bodies with respect to the earth, moon, and the other major planets and their satellites.

The concept is presented of the Russian information and analytical center for asteroid and comet hazards (IAC ACH) as a part of the national IAC for space threats. An overview is given of the center's goals and objectives, as well as the requirements for the center, its structure, and the possible cooperation between the institutes of the Russian Academy of Sciences and other organizations in the creation of the center.

Представлена концепция российского Информационно-аналитического центра по проблеме астероидно-кометной опасности (ИАЦ АКО) как составляющей национального ИАЦ по космическим угрозам. Описаны цели и задачи центра, кратко обсуждаются требования к центру, его структура и возможная кооперация институтов РАН и других организаций при создании такого центра.

Перед фундаментальной наукой астрономией и, прежде всего, перед ее ветвью, ответственной за изучение Солнечной системы, природа и развитие человеческой цивилизации поставили важнейшую практическую задачу изучения космических угроз и поиска методов противодействия этим угрозам. Во исполнение совместного Решения Роскосмоса и Совета РАН по космосу от 23 июня 2010 г. Институтом астрономии РАН, совместно с другими научными и промышленными организациями, подготовлен проект Концепции программы федерального уровня, направленной на создание системы обнаружения и противодействия космическим угрозам. В данной работе рассматриваются основные идеи и астрономическое содержание разработанной Концепции.

The basic science of astronomy and, primarily, its branch responsible for studying the Solar System, face the most important practical task posed by nature and the development of human civilization—to study space hazards and to seek methods of counteracting them. In pursuance of the joint Resolution of the Federal Space Agency (Roscosmos) and the RAS (Russian Academy of Sciences) Space Council of June 23, 2010, the RAS Institute of Astronomy in collaboration with other scientific and industrial organizations prepared a draft concept of the federal-level program targeted at creating a system of space hazard detection and counteraction. The main ideas and astronomical content of the concept are considered in this article.

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 Russian 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 component A 2 in the orbital coordinate system. The presence of this acceleration can be interpreted as the Yarkovsky effect. The statistical properties of distribution of A 2 for asteroids, for which it is determined quite reliably, evidence in favor of this interpretation. The value of additional acceleration for bodies the size of Apophis 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.

The nearest in time close approach of potentially hazardous asteroid (99942) Apophis with the Earth will take place on April 13, 2029, when the minimum distance of the asteroid from the Earth’s center will be as small as 38 000 km. Such a close approach will result in substantial transformation of the asteroid’s orbit. The value of the perturbations depends on the minimum distance between the bodies during the approach. Among possible transformations of the orbit are those which result in new dangerous approaches and even in probable Apophis collisions with the Earth starting from 2036. At present, at least four solutions are known for the Apophis orbit which were obtained using all radar and most of available optical observations. The procedures of assigning weights to conditional equations and the models of the asteroid’s motion have differed to some extent when finding these solutions. Of considerable interest is the comparison of the found orbital parameters with the estimates of their accuracy, since small distinctions in their values result in considerable distinctions in the forecast of Apophis’ motion after 2029 and beyond. It is shown in the paper that the estimates of the probability of an Apophis collision with the Earth in 2036 differ by some orders of magnitude, according to various solutions. The influence of factors which were disregarded in the models of motion even more increases the uncertainty in forecasting the motion after 2029. More accurate forecasting can be achieved as a result of additional optical and, to a greater extent, a series of radar observations in 2013 and then in 2020–2021, and/or as a result of processing radio signals of the transmitter delivered to the Apophis surface or to the orbit of its artificial satellite, as it was proposed in a number of papers.

The results of improving the orbit accuracy for the asteroid Apophis and the circumstances of its approach to Earth in 2029 are described. Gravitational perturbations from all of the major planets and Pluto, Ceres, Pallas, and Vesta are taken into account in the equations of motion of the asteroid. Relativistic perturbations from the Sun and perturbations due to the oblateness of the Sun and Earth and due to the light pressure are also included in the model. Perturbations from the Earth and Moon are considered separately. The coordinates of the perturbing bodies are calculated using DE405. The phase correction and the gravitational deflection of light are taken into account. The numerical integration of the equations of motion and equations in variations is performed by the 15th-order Everhart method. The error of the numerical integration over the 2005–2029 interval, estimated using forward and backward computations, is not more than 3 × 10 −11 AU. Improved coordinates and velocities at epoch JD2454200.5 (April 10, 2007) were obtained applying the weighted leastsquares fit. For the period from March 15, 2004, to August 16, 2006, 989 optical and 7 radar observations were used. The resulting system represents the optical observations with an error of 0.37 (66 conditional equations were rejected). The residuals of the radar observations are an order, or more, smaller than their errors. The system of Apophis’ elements and the estimates of their precision obtained in this study are in perfect agreement with the results published by other authors. The minimum Apophis-Earth distance is about 38 200 km on April 13, 2029. This estimate agrees to within 20 km with those calculated based on other published systems of elements. The effect of some model components on the minimum distance is estimated.

As for comets 619 comets received names from July 2002 to June 2005. Of this naming 76 percent are SOHO comets and 11 percent include the name of the LINEAR project. A revision of the guidelines for naming comets has been completed in March 2003. The assistance of the director of CBAT, Daniel W. E. Green, in redrafting these guidelines was much appreciated by the committee.

The past triennium has continued to see a huge influx of astrometric positions of small solar system bodies provided by near-Earth object (NEO) surveys. As a result, the size of the orbital databases of all populations of small solar system bodies continues to increase dramatically, and this in turn allows finer and finer analyses of the types of motion in various regions of the orbital elements space.