Orbital Dynamics of Small Bodies in the Inner Solar System

Grant #: NNX12AO41G
Senior Scientist: Matija Cuk

This proposal aims to study the orbital evolution of three interesting groups of small bodies in the Inner Solar System: meteoroids originating in the Hungaria region, small binary asteroids, and Mars Trojans. 

The first theme concerns the dynamics of meteoroids originating the Hungaria asteroid group between Mars and the asteroid belt. We will show that delivery routes of meteoroids from Hungarias to Earth or Mars are different than those for the main-belt asteroids. The Hungaria group is dominated by E-type asteroids that are likely parent bodies of aubrite meteorites (Clark et al. 2004), which have the oldest CRE ages of all stony meteorites (Eugster et al. 2006). In Task 1.1, we will use numerical integrations to test if the CRE ages of aubrites are consistent with their origin in the Hungaria family. We will also explore Hungarias as a possible source of meteorites (possibly related to mesosiderites) that were found on Mars by MER rovers (Task 1.2). In both cases, we are exploring a connection between specific meteorite types and an asteroid group. If aubrites can be traced back to 434 Hungaria, and mesosiderites to some other asteroid in the same region, we will gain invaluable information about the past of these meteorites and their parent bodies. 

The second theme focuses on further exploration of the dynamics of binary asteroids. Cuk and Burns (2005) discovered the BYORP radiation effect for small binary asteroids, and Cuk and Nesvorny (2010) pioneered the study of their chaotic rotation and spin-orbit interactions. We propose to expand the approach of Cuk and Nesvorny (2010) by exploring the wider range of secondary sizes and shapes, including the spin-orbit interactions of the primary and multiple satellite dynamics (Task 2.1). In Task 2.2 we will extend this model to all three dimensions, as the spin-orbit interactions tend to behave differently when all angular momenta are not aligned. Our studies of post-formation evolution of binary asteroids complement studies of their origin, and are indispensable for comparison between the theoretical predictions and observed systems. 

At least three of the six presently known Mars Trojans have similar orbits ("Eureka cluster"), with clustered eccentricities and inclinations, and small libration amplitudes. In the third theme, we propose to determine, using numerical integrations, if the present distribution of Eureka cluster members is an artifact of stability or result of diffusion from a past breakup (Task 3.1). The first task will involve integrating both clones of the real Eureka and grids of test particles. We also identify a near-resonance between the Trojans' libration amplitude and a combination of the mean motions of Mars, Jupiter and Earth. In our second task (3.2), we will explore how the existence of this complex three-planet resonance affects the long-term stability and early evolution of Mars Trojans. As Mars Trojans may be the only clearly identifiable remnants of terrestrial planet formation, it is of utmost importance to establish their past dynamical stability, and separate the initially distinct bodies from their later collisional fragments.