Dynamical evolution of two near-Earth asteroids to be explored by spacecraft: (433) Eros and (4660) Nereus.
We have studied numerically the dynamical evolution of the two near-Earth asteroids (433) Eros and (4660) Nereus, to be explored by planned space missions in the next decade, over a time scale of 2Myr. For each real asteroid, we integrated a set of several initially "indistinguishable" orbits (clones), obtained either by small variations of the nominal initial conditions, or by using different computers (introducing different round-off errors). As for Nereus, its orbital evolution is typically dominated by Earth encounters, causing a random walk in semimajor axis. Protection mechanisms related to secular and mean motion resonances are often temporarily at work, but are not likely to increase much Nereus' lifetime. According to our results, it is unlikely that this (C-type) NEA comes from a comet-like initial orbit, or at least that such a transition has occurred in the last =~10Myr. As for Eros, 5/8 clones always stay in the Mars-crossing, Amor-like region, but 3 of them become Earth-crossers within the 2Myr of our integration time span, and indeed one of them was observed to hit the Earth after 1.14Myr. Therefore an Earth impact by this 20-km sized NEA is unlikely but not impossible in the next 10^6^-10^8^yr. Eros probably reached its present orbit by a "slow-track" evolution dominated by Mars encounters, and is a comparatively old fragment originated by a large-scale collision occurred in the main belt.
Astronomy and Astrophysics
- Pub Date:
- September 1996
- CELESTIAL MECHANICS;
- MINOR PLANETS;
- MINOR PLANETS: INDIVIDUAL: 433 EROS;
- 4660 NEREUS