Lai, Hairong - You Know Where the Parent Body is but Where are the Co-Orbitals?

While we can detect and determine accurately the orbits of NEOs down to about 500 m in diameter, our detection rate and accuracy plummets for smaller objects.  At 1AU the typical collision speed between asteroids is about 20 km/sec at which speed a small impactor can completely disrupt a body 10^6 times more massive.  Thus small NEOs can be expected to be sources of co-orbiting smaller objects due to impacts with m-sized and smaller meteoroids.  We have developed a technique to determine the mass of objects that suffer disruptive collisions by measuring the size of the magnetic disturbance that is created in the solar wind plasma by the charged dust released.  By examining the regions around the ascending and descending nodes of asteroid 138175 for over 3 decades with in situ magnetic field and plasma data, we show that there is an extensive trail of debris surrounding the orbit of this asteroid.  The size of this debris is in the hazardous range similar to the calculated sizes of the Chelyabinsk and Tunguska bolides.  The orbits of the debris trail are continuously affected by close encounters with both Venus and the Earth.