Chaos heat map in a-e space using Lyapunov lifetimes (the inverse of the Lyapunov exponent) calculated from 435 000 randomized orbits. The coloration indicated the mean Lyapunov lifetime at that point in space, while the individual black points are fireball data points from the EFN network, and the pink points are the fireballs that lie within 3σ of the 2:1 MMR. The 2:1 MMR is clearly visible in the plot centered at around 3.27 au.