February 21, 2019

09.04.11: 2010 SO16-A World in a Bizzaro Orbit.

Ever wondered what local space would be like if the Earth had more than one moon? Well, it turns out that we do have several natural interlopers; sort of. Recently, researchers A.A. Christou and D. J. Asher of Armagh Observatory in Northern Ireland reported on the discovery of a unique Near-Earth Asteroid (NEA): 2010 SO16, a 200-400 meter space rock locked in a horse-shoe orbit with Earth.

That is, the object is currently locked in a trailing position <0.2 A.U. between the L5  Lagrange point and the Earth, to be slowly released over a period of decades, only to be swept up by the forward position once it orbits around the Sun. The fourth such body known, the horseshoe orbit gives the body a resonance with the Earth that is semi-reminiscent of the quasi-moon of Venus 2002 VE68 we reported on in this space last year. 2010 SO16 is the largest such “pseudo-moon” of the Earth, has both the longest libration period of 350 years, and has been locked in this stable orbit in access of 120,000 years. The object was discovered in late 2010 as part of the ongoing NEOWISE survey.

So, just where could 2010 SO16 have originated from? Well, one theory postulates that the body could be a remnant of the Earth-Moon system itself.  Other examples of horseshoe, tadpole, or even hybrid orbits are known in our solar system, such as NEO 3753 Cruithne and Saturn’s tiny moons Janus and Epimetheus. I doubt it’s a hollowed out cylinder of alien design such as in Arthur C. Clarke’s Rendezvous with Rama, but hey, you never can be too sure… an NEO like 2010 SO16 would make an interesting stepping stone target for a future manned mission, as the energy requirements to get there, stay and depart would be less than your usual Earth-crosser… hey, you heard it first here!

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