Two populations of minor bodies in the outer Solar System remain particularly elusive : Scattered Disk objects and Sedna-like objects .
These populations are important dynamical tracers , and understanding the details of their spatial- and size-distributions will enhance our understanding of the formation and on-going evolution of the Solar System .
By using newly-derived limits on the maximum heliocentric distances that recent pencil-beam surveys for Trans-Neptunian Objects were sensitive to , we determine new upper limits on the total numbers of distant SDOs and Sedna-like objects .
While generally consistent with populations estimated from wide-area surveys , we show that for magnitude-distribution slopes of \alpha \gtrsim 0.7 - 1.0 , these pencil-beam surveys provide stronger upper limits than current estimates in literature .