Last week we got this scaremonger from Universe Today: undiscovered Venereal coorbitals. Sounds like something you need a urologist for. But seriously - Carruba et al., arxiv.
The paper is talking 1:1 down in the Solar well, so something like Cruithne up here; also, L4 and L5 rocks, like 2013 ND15. They call the former, "horseshoe"; the latter, "tadpole" - both, low-eccentricity, so they offer some high-e 1:1 as well. In fact most observed co-orbitals are high-e; they cannot account for this by dynamics, so blame observational bias.
If low-e, you'd think - why should Earthlings even care. Carruba points to an earlier study he'd done: they switch orbits. What we don't know can hit us. If nothing else, this blog should ponder von Zeipel: a high inclination, low eccentricity orbit can switch to a 3.4° inclination, high-eccentricity orbit. Overall they bring a Hamiltonian equation on how these orbits can flip type. This raises Lyapunov exponent, which 10 Hygeia knows all about. The paper flips that exponent for 150 years, before these rocks can't be predicted.
The mathematic indulged here is the (e,i) plane.
The paper suggests putting a sort of JWST-Venus at SVL2 to block out the sun and Venus both, to do a search for these co-orbitals. (Or STL2, but we're kinda using it. Either planet's L1 might also work: we might not care that the planet is reflecting light at its back.)
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