Title: Many binaries among NEAs
Authors: David Polishook, Noah Brosch

The number of binary asteroids in the near-Earth region might be significantly higher than expected. While Bottke and Melosh (1996) suggested that about 15% of the NEAs are binaries, as indicated from the frequency of double craters, and Pravec and Harris (2000) suggested that half of the fast-rotating NEAs are binaries, our recent study of Aten NEA lightcurves shows that the fraction of binary NEAs might be even higher than 50%.
We found two asteroids with asynchronous binary characteristics such as two additive periods and fast rotation of the primary fragment. We also identified three asteroids with synchronous binary characteristics such as amplitude higher than one magnitude, U-shaped lightcurve maxima and V-shaped lightcurve minima. These five binaries were detected out of a sample of eight asteroids observed, implying a 63% binarity frequency. Confirmation of this high binary population requires the study of a larger representative sample. However, any mitigation program that requires the deflection or demise of a potential impactor will have to factor in the possibility that the target is a binary or multiple asteroid system.

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`Irony` actually does mean `metal like`...

Binary asteroid might make a mitigation attempt interesting, should one be on a collision coarse with Earth.

It might make it easier--changing the course of the smaller of the two would probably affect the course of the larger one.

Todd