  Cold debris disks (T$<$200 K) are analogues to the dust in the Solar System's
Kuiper belt--dust generated from the evaporation and collision of minor bodies
perturbed by planets, our Sun, and the local interstellar medium. Scattered
light from debris disks acts as both a signpost for unseen planets as well as a
source of contamination for directly imaging terrestrial planets, but many
details of these disks are poorly understood. We lay out a critical
observational path for the study of nearby debris disks that focuses on
defining an empirical relationship between scattered light and thermal emission
from a disk, probing the dynamics and properties of debris disks, and directly
determining the influence of planets on disks.
  We endorse the findings and recommendations published in the National Academy
reports on Exoplanet Science Strategy and Astrobiology Strategy for the Search
for Life in the Universe. This white paper extends and complements the material
presented therein with a focus on debris disks around nearby stars. Separate
complementary papers are being submitted regarding the inner warm regions of
debris disks (Mennesson et al.), the modeling of debris disk evolution (Gaspar
et al.), studies of dust properties (Chen et al.), and thermal emission from
disks (Su et al.).
