1. ИПА РАН
New opportunities of the computing-analytical complex for predicting collisions of the Earth with asteroids and comets and creating scenarios of collision catastrophes produced by celestial body falls
1Yu.A. Chernetenko, 1O.M. Kochetova, 1V.A. Shor, 1D.E. Vavilov, 1T. A. Vinogradova, 2A.V. Zaitsev, 1N.B. Zheleznov
1Institute of Applied Astronomy of RAS, St. Petersburg
2NCP Planetary Defense Center, Khimki, Moscow district
This complex was created by group of developers – representatives of various organizations, partly under contracts with Emercom of Russia. In this report new opportunities of the complex are provided. In prior publications the organization of search of potentially dangerous body approaches to the Earth has been considered. In the course of computation two standard situations may take place:
the body on the nominal orbit passes by the Earth, then its minimum distance from the planet center is calculated, as well as collision probability taking into account uncertainty of body orbit is calculated, or
the body in the nominal orbit penetrates into the terrestrial atmosphere up to the certain height above the surface of the Earth spheroid.
In the latter case the scenario of the possible catastrophe caused by collision of a body with the Earth is constructed.
In present report the boundary case is considered when the body in the nominal orbit does not collide with the Earth, but the probability of collision is enough great (e.g., greater than 10-3). In this case the real body has rather good chance to collide with the Earth. It is necessary to determine beforehand the area of a terrestrial surface where fall of above celestial body is possible. In other words, it is required to determine passing of a strip of risk along the Earth's surface.
Besides, in the report the question of collision of bodies with the Moon is considered. At last, the forming on the website of the IAA RAS the table of the past and forthcoming approaches of potentially dangerous bodies to the Earth and the Moon is described.
Calculation of the strip of risk passing on the Earth surface
Among the elements of the body orbit most poorly defined from short-arc observations is the mean daily motion of the body. On the other hand, the minimum distance at which the body passes the center of the Earth primarily depends on value of the variation of the mean motion relative to the nominal value. Minimum of all possible distances between the body and the center of the Earth is achieved in such cases, when the body and the Earth simultaneously pass through opposite ends of the segment which has the shortest length between their orbits. Body moving in accordance with the nominal solution, however typically intersects the segment of the shortest distance between their orbits sooner or later than the Earth. Therefore, the minimum possible distance between the bodies is not achieved. By variation of body mean motion it is possible to achieve simultaneous arriving of the body and the Earth to the ends of segment of shortest distance and thus find the minimum possible distance between the body and the Earth. If the distance is less than radius of the Earth, then collision takes place. All collisions occur in a small neighborhood of the shortest distance between the orbits. Therefore calculation for strip of risk points must be started from search of variation of the mean motion which leads to minimum possible distance between body and the center of the Earth. Then, by varying the mean motion in the surrounding area, it is possible to find other points. To shorten and simplify the calculation by the scheme described above, it is important to estimate extent to which the minimum distance from the center of the Earth F, can be shortened depending on the element errors (or other parameters of orbit).
Fig. 2 shows found by this method the strip of risk for a fictitious asteroid whose orbit has been determined from 23 observations of asteroid (099942) Apophis, taken at the time interval from to December 2004.
Fig. 1 shows the strip of risk for fictitious body whose orbital elements were found from four observations of real body 2016 LP10 taken in the time interval from to
Time when the body passed by the Earth at the minimum distance from the Earth center
JDT =
The minimum distance from the Earth center
± km.
The probability of collision
0.128E-01
Time when the body passed by the Earth at the minimum distance from the Earth center
JDT =
The minimum distance from the Earth center
64648 ±17602 km.
The probability of collision
0.62E-03
Collision with the Moon
While the moon is no human settlement, the collision of cosmic bodies with it is not a serious threat. However, the clash with a large space body in a position to throw outcrater formed by hundreds, if not thousands of times greater weight substances falling body. Part of the ejected matter may acquire speed, greater escape velocity from the surface of the moon. Ultimately, the most part of this substance will fall back to Earth, as particularly evidenced by meteorites finds identical composition lunar rocks. Observation of falling bodies on the moon is of interest to different areas of knowledge. Targeting of the impact area to perform efficiently in selenographic coordinate system, which usually indicates the position of craters and other formations on the lunar surface.
Task prediction of falling bodies on the moon differs little from the analogous problem for the Earth. Instead, the scope of the Earth used the scope of the moon, and instead capture the Earth radius is substituted capture radius of the moon. Entrance height h in the atmosphere is assumed to be zero above the lunar surface. Determined selenographic coordinates of the point of incidence and time World time. All calculations are performed for the moon after those of the Earth, of course, in the event that a collision with the central body is not fixed. Simulation of the collision with the Moon can be organized on the model of the collision with the Earth. It should be borne in mind that the moon's orbit is osculating varies considerably stronger the Earth's orbit. Therefore, when searching for the body of convergence points with the forecast of the Moon encounters should be carried out at shorter intervals.
In Fig. 3 the strip of risk for asteroid 2008 TC3 is shown
Time when the body passed by the Earth at the minimum distance from the Earth center
JDT =
The minimum distance from the Earth center
± km.
The probability of collision
0.128E-01
13th EVN Symposium and Users Meeting
20-23 September 2016, St. Petersburg, Russia