Program: GN-2008A-Q-29

2003 EL61, the third brightest Kuiper belt object know, is circled by a pair of small satellites in gravitationally interacting orbits. The inner satellite is sufficiently perturbed that the currently available data cannot be fit with a simple Keplerian orbit, but the data do not yet exist for a full three-body fit. Such a full fit will give strong constraints on the masses and histories of all three bodies in the system and allow the first detailed study of the after-effects of a mantle shattering impact in the outer solar system. Twelve snapshots, approved for 2007a, would have sufficed to provide a full orbital fit, but only 4 snapshots were obtained that semester. Eight more are still needed to complete this program. Observations such as these, with guarenteed results from relative astrometry on relatively bright point sources and an analysis by a produtive team well versed in LGS AO, are an excellent use of this powerful facility.