On the orbital evolution of 2020 AV2, the first asteroid ever observed to go around the Sun inside the orbit of Venus

The innermost section of the Solar system has not been extensively studied because minor bodies moving inside Earth's orbit tend to spend most of their sidereal orbital periods at very low solar elongation, well away from the areas more frequently observed by programs searching for near-Earth objects. The survey carried out from the Zwicky Transient Facility (ZTF) is the first one that has been able to detect multiple asteroids well detached from the direct gravitational perturbation of the Earth-Moon system. ZTF discoveries include 2019AQ3 and 2019 LF6, two Atiras with the shortest periods among known asteroids. Here, we perform an assessment of the orbital evolution of 2020 AV(2), an Atira found by ZTF with a similarly short period but following a path contained entirely within the orbit of Venus. This property makes it the first known member of the elusive Vatira population. Genuine Vatiras, those longterm dynamically stable, are thought to be subjected to the so-called von Zeipel-Lidov-Kozai oscillation that protects them against close encounters with bothMercury and Venus. However, 2020AV(2) appears to be a formerAtira that entered theVatira orbital domain relatively recently. It displays an anticoupled oscillation of the values of eccentricity and inclination, but the value of the argument of perihelion may circulate. Simulations show that 2020 AV(2) might reach a 3:2 resonant orbitwithVenus in the future, activating the von Zeipel-Lidov-Kozai mechanism, which in turn opens the possibility to the existence of a long-term stable population of Vatiras trapped in this configuration.