In this post, I reviewed a paper that studied a peculiar binary asteroid system called (617) Patroclus-Menoetius that orbit around the Sun in a similar path as Jupiter (just 60 degrees behind Jupiter in its orbit). Binary systems contain two similarly-sized objects in orbit around a mutual center of mass (think more along the lines of Pluto and Charon, rather than the Earth and Moon). Binary asteroids are interesting because they’re likely some of the oldest relics in the Solar System. They probably formed when the cloud of “pebbles” that comprised the early planetesimal disk was still condensing and could easily form pairs of objects. Over time, though, encounters with other objects (like other asteroids or big planets) can disrupt binaries, causing them to collide or drift apart. The fact that Patroclus-Menoetius has survived the entirety of the Solar System’s lifetime can put some strong constraints on possible events in the Solar System’s history that would have otherwise disrupted the pair. The authors of the paper ran simulations of the early Solar System to figure out the conditions in which a binary pair like Patroclus-Menoetius could survive.
I won’t spoil the answer here, you’ll just have to go read the post! But what’s especially exciting is that NASA’s Lucy mission, due to launch in 2021, will visit this curious binary system in 2033. So we’ll soon know even more about this system and be able to place even stronger constraints on conditions in the early Solar System!
[Image is an artist’s rendition of Patroclus-Menoetious. (Credit: W.M Keck Observatory/Lynette Cook)]