posted on Jun, 10 2004 @ 09:22 AM
Toutatis will pass by earth on 29th September 2004. The closest NEO of such huge proportions in this century.
"ABSTRACT: Minor planet 4179 Toutatis is an Apollo type object with a very small orbit inclination (i=0.47 arcdeg), hence it has a possibility to
approach closely the Earth (an encounter to within 0.01 a.u. is expected in 2004) and might be a good candidate for a future collision with the Earth.
We collected 640 astrometric observations of Toutatis from the period 1934-1997 to improve the orbit. We had to include a nongravitational term into
equations of motion expressed by a secular change dot[a] of the semi-major axis a of the Toutatis orbit to obtain a fully satisfactory solution of the
orbit determination. A value dot[a]=-0.16*10^[-10] is two orders smaller than that determined in the case of short-period comets with known
nongravitational effects. To investigate the long-term motion of Toutatis we numerically integrated the equations of motion by recurrent power series
taking into account perturbations caused by the eight planets from Mercury to Neptun, treating the Earth and Moon as separate bodies, and also by the
four biggest asteroids. We randomly varied the orbital elements to examine the Toutatis' motion for a number of different orbits. We present a new
method of the random orbit selection which allows us to find a set of different orbits but representing well all the observations used for the orbit
correction. Our results confirm a conclusion found by other authors that Toutatis orbit is exceptionally chaotic. Therefore, we are not able to
predict the motion of Toutatis further than for 300 years. However, our integrations spanning 1500 years showed that the evolution of position of the
descending node of Toutatis' orbit might go also in such a direction that the orbits of Toutatis and of the Earth would intersect in the future.
Hence a possibility of the Toutatis-Earth collision is not excluded but it is completely unpredictable. To investigate conditions of a hypothetical
collision of a minor planet with the Earth we made the following numerical simulation. Based on the Toutatis' orbit we deduced such orbital elements
for a fictitious minor planet "Fatum" that a shape of the orbit was very similar to that of Toutatis, but we knew in advance that "Fatum" would
certainly collide with the Earth in September 2004 and we calculated values of the impact parameters. We created a set of 638 artificial observations
of "Fatum" in 1988-1997 for the same dates and with the same random observational errors like those of Toutatis. Then we corrected the "Fatum's"
orbit for different observational intervals to examine the exactness of the impact prediction in 2004. We found that in 1993 we would be sure that the
collision is inevitable, and in 1997 we could determine an impact area on the Earth's surface in range of a square of 100*100 km. We show that if we
knew the impact date so early we could undertake an action to avoid the collision by trying to change the "Fatum's" heliocentric velocity only by
one cm/sec. "