Close approaches to the terrestrial planets by the NEAs

In general there are computed and published close approaches to the Earth by asteroids or by comets, for example NASA Risk Page (http://neo.jpl.nasa.gov/risk/) or NEODYS www site (http://newton.dm.unipi.it/cgi-bin/neodys/neoibo). Computation are mainly referred to the Earth Impact Risk.

The main goal of this work is to show all of the possible close approaches of the Near Earth Asteroids with all terrestrial planets, from Mercury to Mars and with Moon. In order to attain this the orbital elements of all known minor planets which orbits cross the orbits of planets were extracted from Lowell catalogue (ftp://ftp.lowell.edu/pub/elgb/astorb.html). The equations of motion of these selected asteroids and the planets with Monn treated as separated body were integrated 575 years forward using Everhart's RA15 (RADAU) method from Mercury Integrator Package v. 6 by J. Chambers. The starting orbital elements of planets were taken using ephemeredes DE405/WAW of prof. Grzegorz Sitarski from Space Research Center Polish Academy of Science in Warsaw.

Results of the computations are presented below. This presentation show the close approaches with the terrestrial planets. For example, in the forthcoming 575 years couple of minor planets can close approache Mercury even below 0.002 AU (300,000 km). The following table lists, in order of increasing hermocentric distance, the closest known approaches to Mercury by asteroids.

distance year minor planet diameter of minor planet

[AU] [thousands of km] [km]

0.00158 237 2084 2000 DO1 0.4

0.00162 243 2183 2000 JG5 1.1

0.00199 299 2152 2000 JG5

0.00251 377 2096 2001 CP36 0.2

0.00252 378 2340 2000 JG5

0.00280 420 2201 2002 FB3 2.5

Next approaches with the other terrestrial planets will be presented on MACE 2004 in Italy.