Astro2020 Science White Paper: Probing the Structure of Interstellar
  Dust from Micron to Kpc Scales with X-ray Imaging
  The X-ray regime is a largely underused resource for constraining
interstellar dust grain models and improving our understanding of the physical
processes that dictate how grains evolve over their lifetimes. This is mostly
due to current detectors' relatively low sensitivity and high background,
limiting the targets to the brightest sources. The improved sensitivity of the
next generation of X-ray detectors will allow studies of much fainter sources,
at much higher angular resolution, expanding our sampled sightlines in both
quality and quantity.
