At 40 or more astronomical units from the Sun and with diameters of hundreds of kilometers, these objects are unaffected by YORP. And as noted earlier, impacts are extremely rare in this vast region of space, at least today.
No matter how a binary forms, the story doesn't end there, particularly for those that may have been created by YORP. The angular momentum of a fissioning system undergoes wild changes and is initially unstable.
Studies by Pravec, Warner, and others, now suggest that the spin-up caused by the YORP effect is the dominant mechanism for the formation of small binary asteroids.
One of the first proofs of the YORP effect was obtained by Stephen Slivan.
However, observations of a small near Earth asteroid by the name of (54509) 2000 PH5 by the Faulkes Telescope North, when combined with data from various other professional instruments, had revealed the rotation period of the asteroid to be decreasing by around a millisecond each year, in agreement with theoretical predictions of the magnitude of the YORP
effect for this object.
To understand how the YORP
Effect works on asteroids, Tel Aviv University researchers examined several variables relating to these asteroids, including size and location.
According to Bottke, YORP
compels prograde objects to migrate toward axial tilts of 0[degrees], while retrograde objects work toward obliquities of 180[degrees].