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Asteroid Radar Astronomy - The Case of 4179 Toutatis

Event Details

Event Dates: 

Friday, August 10, 2012 - 6:00am

Speaker Name(s): 

Michael Busch

Speaker Affiliation(s): 

NRAO
Seminar Type/Subject

Event Details & Abstract: 

The near-Earth asteroids are a population of objects on orbits which cross or pass near that of the Earth. They are a diverse population, ranging from small rapidly-spinning cohesive objects to larger rubble-pile objects with satellites, with shapes, spins, and trajectories that are dramatically influenced by radiation pressure effects driven by sunlight.Observations with the Arecibo and Goldstone planetary radars are one of the most powerful techniques for observing near-Earth-asteroids, providing resolution as fine as 4 meters on dozens of objects. I will review recent asteroid radar results with a focus on one particular object, 4179 Toutatis.Toutatis is close to a 4:1 orbital resonance with Earth, and has made close flybys of Earth every four years since 1988. It has been imaged with radar during each approach since 1992, showing that it is an elongated bifurcated object with a non-principal axis spin state. Toutatis' spin changes with time, torqued by terrestrial and solar gravitational tides. Measurements of the asteroid's moments of inertia from radar imaging show that its interior is not uniform density - material is segregated along its long axis. Toutatis will make its last close Earth approach until 2069 this December, and the Cheng'e 2 spacecraft will fly by the asteroid in January. I will describe the planned campaign of radar observations during the approach, and make predictions for what both ground-based radars and Cheng'e 2 will see.