The invisible threat: Assessing the collisional hazard posed by undiscovered Venus co-orbital asteroids

Context. There are 20 co-orbital asteroids of Venus currently known. Only one of them exhibits an eccentricity below 0.38. This is most likely caused by observational biases since asteroids with higher eccentricities have a higher probability of approaching the Earth and are easier to detect. Aims. We aim to assess the possible threat that the as-yet-undetected population of Venus co-orbitals might pose to Earth and investigate their detectability from Earth and space observatories. Methods. We used semi-analytical models of the 1:1 mean-motion resonance with Venus and numerical simulations to monitor close encounters with Earth on several co-orbital cycles. We analyzed the observability windows and brightness variations for potential Venus co-orbitals, as viewed from ground-based telescopes to assess their future detection feasibility with next-generation survey capabilities. Results. There is a range of orbits with e < 0.38, larger at lower inclinations, for which Venus'co-orbitals can pose a collisional hazard to Earth. Conclusions. Current ground-based observations are constrained by periodic observing windows and solar elongation limitations; however, the Rubin Observatory might be able to detect some of these objects during favorable configurations. Space missions based on Venus'orbits could be instrumental in detecting Venus'co-orbitals at low eccentricities.