Near-Earth Objects’ Highways: dynamical evolution, fates and lifetimes

It is well known that the Near-Earth Objects population is sustained by
bodies that migrate inwards coming from outer regions of the Solar System.
The usual understanding is that once these objects become NEOs they are
at the end of their lives, with an expected life of approximately 10 Myrs
before probably hitting the Sun. But that is only part of the story. We aim to
revisit the dynamic evolution of the NEO population inside the Solar System
using a large sample of real objects. Therefore, we separate the phase space
into five different regions: Near-Earth Objects (NEO), Main Asteroid Belt
(MAB), Jupiter Family Comets (JFC), Centaurs (CEN) and Trans-Neptunian
Objects (TNO). We performed numerical simulations for more than 5000
NEOs for 100 Myrs and tracked their transitions between regions to
determine the most common routes and fates for this population. We find
that, during their dynamical evolution, more than half of the objects are first
transferred to the JFC region and make their way out from the Solar System
through it. There is also a significant frequent exchange of bodies between
NEO and MAB regions, in both directions. At least 1/3 of the bodies move to
the MAB region, but less than 1% of them end their lives inside it. So, we
can conclude that MAB is a transitional region where bodies briefly pass
through. We also found that only about 15% of the bodies never leave the
NEO region. From those, 2/3 collide with the terrestrial planets and the
remaining 1/3 survive for the whole integration of 100 Myrs. Additionally, we
show that almost 10% of the studied sample can reach the CEN region and
remain there for a substantial amount of time, telling a different side of the
story for the NEO population.