Complex sentence: The "Hayabusa" images show a surprising lack of impact craters and a very rough surface studded with boulders, which were referred by the mission team as being in a'rubble'.
Split into simpler sentences: The "Hayabusa" images show a surprising lack of impact craters, but a very rough surface studded with boulders. These particular boulders were referred by the mission team as being in a'rubble'.